CH110342A - Improved rotor for a steam turbine and method for producing the same. - Google Patents

Description

  

  Improved rotor for steam turbine and method for producing (the same. The higher one supports multi-stage steam turbines and in particular those of the action type with .their impellers. larger, and their ever increasing peripheral speeds, has inevitably resulted in frequent ruptures of the impellers and blades, and quite often the result of these ruptures is even total destruction of the entire turbine.

   The true causes of these disturbances have not yet been discovered and accidents in steam turbines have become more and more frequent.



  However, it has been found that the ruptures of the impellers and blades of steam turbines are mainly due to development in the impellers. (the oscillatory movements or oscillation ,. These oscillations are propagated in the: wheels with (the speeds which depend on any one of a number (the natural frequencies of vibrations of the wheel itself.

   It has been observed that if these oscillations propagate in the wheel in a direction opposite to that of the rotation of the wheel. dangerous conditions are created, if the backward speed (the oscillations is equal to the forward speed of rotation of the wheel: In such conditions a backward oscillation becomes stationary in space, and the amplitude d Such oscillation can thus become very large because the wheel is subjected to a stationary force in space tending to bend the wheel in an axial direction.

   The repeated bending stresses produced in the wheel by the oscillations which propagate therein ultimately lead to fatigue breaks in the body of the wheel.



  The present invention includes an improved rotor for a steam turbine and a method for making the same.



  This rotor has several wheels <B> on a </B> same shaft, at least one of which exhibits a critical speed, that is to say at which the oscillations occur which become stationary in space and of a precise amplitude, in the vicinity of the speed normal operation of the rotor, and it is characterized in that no. these wheels have a critical speed closer to the key speed key normal operation than about 10 of the latter, in order to prevent service disturbances due to the phenomenon of bone cillations.



  The invention will be more easily understood by the description which will follow with reference to the accompanying drawing, given by way of example: The fit. 1 shows, by way of example, a 17-stage 30,000 liffl turbo-generator built according to the invention, the cover of the turbine casing being removed in order to show the impeller wheels of the turbine. In this figure, the turbine shaft is designated by 1; the first wheel or the key high pressure wheel the series of wheels on the rotor is denoted by 2; and that of the last or 17th floor by 3; 4 designates the alternator actuated by the turbine.

   One sees, for example at 5, the end of the lower half (the a steering disc between the turbine wheels; The fi. \? Is a view of a turbine rotor showing the remainder of a impeller, part of which has been torn off; La, fi-.3 is a view of a turbine impeller, of which a peripheral section extending only a small extent into the disc of the impeller has been torn off; fit. 4 is a view of a tur bine key wheel in which the rupture extends only over the blades themselves, while fit. 5 shows on a larger scale <B> a </B> damaged fragment of the wheel shown at the end. 4; The end. 6 is a view of raked fragments of a broken turbine wheel;

    The fit. 7 shows a director disc damaged by friction; The end. 8. 9, 10 and 11 show different examples of figures of no dal vibrations in a turbine wheel; The end. 12 is a perspective view of an electric machine that can be used for testing turbine wheels, while Les fib. 13, 14 and here we represent parts in detail; The fiâ. 16 is an electrical connection diagram for this machine; The fi-. 17 to 21 show typical dia-ramnias recorded by an oscillograph;

    The fib. 22 and 23 are diagrams showing the relationships between the rotational speeds and the frequencies of oscillation of key turbine wheels; The fit. 24 and 25 are typical diagrams showing the critical speeds for different impellers of a turbine rotor, in which several of the critical speeds fall in the dangerous vicinity of the normal running or operating key speed;

         The fit. 26 and 27 are diagrams showing the relationship between critical speeds and the running speed of different wheels of two turbine rotors in which none (the critical speeds fall into dangerous proximity to the normal running speed;

    The fi-. 28 ii 34 are key cross sections of turbine wheels and show the removal of key material-key portions of a wheel for the key purpose of tuning "; Les firi. 35,: 36. 37. 38. 39 et 40 are (detail views of a device for vibrating a key turbine wheel disc.



  Although the development of the construction of steam turbines has been around for a long time (years, it has only been about ten years ago that there has been concern (disturbances to the paddlewheels of key rotors turbines steam; in particular of the action type, due to bursting or breakage (the discs of wheels or blades themselves.

    In the early stages of development. these disturbances were comparatively rare and they only appeared when building more and more turbiiles. <B>, </B> a large.

    In many of these large turbines, the impeller discs (the impeller were indeed shattered and large fragments of the impellers were even thrown away, so that not only the impeller was demolished. But neighboring devices were also destroyed,

      and in many cases these accidents caused even the loss of human lives ('s.



  The, fig. -t (bed d (# s.ül shows a rtil) ttlre (the one turbine wheel disc extending deep into the disc itself and we see that a large section of the whole impeller <B> - he </B> the aubey climb, it was ripped off.

   It is necessary. note that the edge (the central part of the break indicated in G is of a particular appearance in a way winged which we did not bend well to represent has sin. niais which always characterizes the breaks by ( the tension forces. The general perimeter <B> (the </B> this part follows approximately an arc of a circle of relatively small radius.

   The outer sections 7 and 8 of the. breakage show less acenfied marks of stress fatigue. The sibnification of this kind of rupture will be. explained further: far.



  As the weight (Fitn such a fragment of r (ltlcl. Coinille indicated ell fig.?, Can rise dc! _ ';' I, up to 1? 5 l:

  b and since the peripheral speed of the wheel is not significantly different from the initial speed of a shell, oli can easily understand how much energy is being unleashed. by a break <B> (the </B> ci-, kind.



  The. Fib. 3 shows part of a large steam turbine after failure of the general character described. 0, only sees the envelope or frame of the.

   turbine has been demolished as shown in (). In this case, the entangled section of the wheel extends only slightly into the wheel disc body as shown at 10. The character of the break at 10 which cannot be well shown in a drawing. here also indicluc a fatigue failure. He is at.

   notice that the break line passes through holes 11 and 1 ?.



  The fi ,, -. q shows a disk (the turbine wheel provided at 13 with a single peripheral row of blades 1-l. This figure was made from a pliotoography and shows the turbine rotor mounted on a shaft and placed on a support 15. He points out <B> (thread 1 </B> he <B> he </B> number of blades .l been torn from the wheel <B> like </B> indicated <B> to </B> free places: lti, 1 7 and.:.

    Read thread. 5 shows, on a larger scale, a view (the broken blades corresponding to the key section # ibilée by 17 in fib. I.

   The nature (the ruptures at the places where the vanes have been broken, as for example at 18 and 1 \ J, indicate as above a rupture due to the action of fatigue. It should also be noted that ' a vane has been torn off at? 0 and the tenon? 1 still holds on to the tire \ ??. As will be shown below, the oscillation produced in this turbine wheel causes tearing (the tenon by shearing and this.

   not only in this case. ? 1. but also in the case of the tenon of which. the rest is visible in? 3. It should be noted that the fatigue failures in the examples shown in fig. d and in detail eu fib. 5. only touched the blades and did not come off at all. (tans the disc of the wheel. @ \ - utremeiit (bed, the radial depth at which the breaks;

   by fatib ie occurred in the wheel shown in fi-. 4, is much lower than that of the wheel shown in FIG. 3.

   It should be noted that with the ruptures (the turbine blades themselves. The bands were also torn off: in several places of the periphery <B> (the </B> the wheel as, for example, at points <B> 16 </B> ët <B> 17 </B> already mentioned.



       The fi-. G shows fragments. of a turbine wheel picked up after an accident and relocated as shown. It should be noted that in this case as well (read in that of fig. 3, a contour line of the broken sections passes through certain steam balancing holes indicated at '1-t and \? 5. It is also to be noticed in this figure that by some action (the rubbing lies;

   the blades have been melted in place, as a result of the intense heat produced.



       Another manifestation quite often encountered is that illustrated in fi ,, 7. This figure represents a stationary steering disc, which, as we know, is situated at the front of the turbine wheels.

   This disc is made of halves along a horizontal plane of division 27 and is assembled around the shaft with suitable gaskets to prevent vapor flow through the hole through the shaft. This director disc comprises a central flange if # '_ ide and iodine row etfzi = @: 4th of nozzles 29.

   It can be seen from the drawing that the nozzles in the opposite di-ibetral reions designated 30 and 31 have apparently been brushed or rubbed by some rough body, while in the other parts of the steering disc such friction did not happen. An explanation will be given later.



  Much research has. been made by those skilled in turbine construction with a view to overcoming the difficulties arising from breaks and similar disturbances of the general nature described above. Explanations of all kinds have been given to realize these difficulties. It could be assumed that centrifugal forces were the cause for the most serious ruptures.

   Careful calculations of the forces generated and the resistance (the material of the wheels have, however, demonstrated that such a wide margin of safety exists with regard to centrifugal forces that such an explanation is in no way admissible.



  In <B> le </B> case of large (disks (the tur bine, we have a buplxised time that (Ps itiébalities of heating of the -disks, which are hotter. Near the.

       periphery that near the center could cause so-called disc deformation to some wavy shape along the periphery, so that parts of the disc could come into contact with adjacent steering discs ott (other parts of the turbine .

    However, we cannot use (this explanation for the friction on a dis que # lir @@ @ t @ # ur en des rit.; I @ 3iis (lr, terinhiées equi (lis @ taiaes as in <B> 30 </B> and 31 in fi. 7.



  Shortly after the difficulties. (Read from friction and breakage (the turbine wheels began to pop up, he was subberated by Professor Stodola, a recognized skill in steam turbine construction, -in a article published in the "Revue Polytechnique Susse" of May 2, 1914 under the title (in translation) of "On the vibrations of wheels of rotating turbines", that the wheel discs themselves were set in vibration and that these vibrations could ,,

  become so sharp that the edge of the wheel could come to rub against stationary parts which immediately heat up red, so that very dangerous conditions are created. "Stodola undertook a complicated mathematical investigation of a purely nature on this point. theoretical, in view of realizing the difficulties observed,

   and he concluded that the vibrations generated in the turbine were nodal vibrations and that they were to be expected to become dangerous as a result (the resonance with axial vibrations caused by the partial peripheral admission of steam into the say that of the turbine, or as a result of certain construction faults such as, for example,;, when the steam heats the edge of the wheel periodically in certain places ".;

  However, this attempt at explanation only applies in the case of the first stage (the turbine, while most of the difficulties of the character "; generally described have been manifested in the larger impellers (the rotor, in low pressure stages. Siodola offered no practical remedy. Difficulties:

  As a result (the ruptures in the rotors of the steam turbines not only continued, but became more and more serious) with the increase (the size (the turbines built and started. In addition the disturbances) occur in turbines with total peripheral steam inlet and not (in those with partial peripheral inlet.



  A list <B> (the </B> several (the these accidents, together with (the other details which showed themselves in the march of the brandes steam turbines have been (drawn up by Tsar Bauniann in the article entitled ..Recent Results of the Development of the Practice of brandes turbines à steam ", published in the" Journal of the Institution of Electrical Enbinéers (London), Vol. 59, 1:

  121, pages <B> 565 </B> â 663 '\. After a description (the difficulties which have been shown, in practice, in the closed wheel operation (the steam turbines, in:

  @ particular of large diameter, dukes in one way or (the other to (the vibrations of the same words, the author indicates on page 620 that, .as a result of the lack (the proposals @ atisfaisantes to obviate the difficulties in practicing due to direct or indirect use (high peripheral speeds,

   the trend ii. employing such high peripheral speeds has been a definite failure and a more conservative policy is now more appropriate to obtain satisfactory results. It is therefore essential that the rigidity of the discs is such that their vibration is excluded. "'In the discussion of this article Msr. S.

   E. Fedden proposed. (page 630), as a remedy for these difficulties, that the wheels or rotors be periodically removed and (the new mounted, so as to avoid (the disastrous results (read the effects of fatigue as a result of repeated efforts.



  He said: ,, I think we should. after a certain period of time, remove the rotor and put it back on again in order to be sure and prevent a catastrophe. "And then he says:,; There must be something (the wrong - in the calculation and the construction). tion of these turbines to cause such a number (ruptures. Undoubtedly the turbine builders should work together to learn how these difficulties could be overcome. "atfr. Kaula. says (page 633):

      "However, the main obstacle, in the construction of brand units, seems to be the difficulty of obtaining a disc of a uniformly coli material (the (the part associated with disc vibration, about which we <B> know </B> very place.

   The last problem is closely related to that of critical speeds (that is, critical speeds of the shaft) which arose in 1912, when the author wrote his previous article. "And Mr. Iiaula written;

  i new (page 634) ... If subsequent experiments prove that different forms of vibrations which can be transmitted to the disc in one form or the other, are liable to generate (the resonant vibrations of an order danbereut in the disc, it will be necessary to determine two factors: first what kind of vibrations cause such effects, and secondly what is the period of these vibrations.

   If these two factors can be predetermined, it should be comparatively easy to get the natural period of all discs to remain well removed from the periods of vibration in question. "I. Dr. Stodola. Himself provided an explanation. discussion in the same publication (page 637), but it gives no remedy for the difficulties mentioned.



       -Bauma.nn proposed (page 638), as a solution, that the use of large discs should be avoided, and he further recommended (page 6-1?) That, the discs used should not vibrate in any condition "and that they should work with (moderate peripheral speeds.



  It would, however, be a step in the wrong direction in the development of steam turbines for modern use, to reduce the diameter of the wheel disks and their normal running speed, and all this in order to avoid difficulties due uus vibrations of discs or bent nomenes of oscillations. It is well to remember that the application of the gas turbine to the control of electric generators has been one of the most important steps in the development of the industry.

  electric. During the last decade, the group size has continuously increased to the point that a 35,000 Ii \ V turbine has now become.

   a normal unit. It is in the first place thanks to this increase in size, as well as to the band increase in peripheral speeds, that the electrical efficiency per unit of steam of the current large turbo-generators is approximately double that of of the best machines built in 1903.



  This progress. enormous in potency and efficiency is of the utmost importance for practice. This is not to say too much if Won claims that the replacement of the steam engines by the modern turbo-generators and the corresponding reduction in the construction costs of the whole central station together with the corresponding savings made on the service costs, made possible the use of large modern power stations.

   Consequently, one cannot take into consideration, with the possible exception of a few special cases, any proposal to obviate the difficulties resulting from the phenomena of oscillations in the disks or wheels of turbines, which may have for consequently the reduction of the power on (the efficiency of a turbine.



  As a result of extensive research, it has been found that it is not necessary at all, in order to obviate the difficulties due to the phenomena of oscillations in the turbine wheels or in the blades, that the wheel be so reinforced. and its peripheral speed so low that all vibrations are completely avoided.

   On the contrary, according to the invention, key tur bine wheels are now regularly produced which, while being subject to oscillation phenomena at certain speeds in the proximity of the normal running speed of the machine. wheel. these difficulties are nevertheless completely free key at the key speed normal running and: at all speeds which do not differ key there. key speed works normally only by one margin (the pre-determined safety.



  The rotational speeds of disks at which major oscillation phenomena occur (develop, may be called.; Critical speeds "," critical speed "used in this description denotes this critical speed which arises from the tendency of the turbine disc. to give rise to oscillation phenomena corresponding to radial node conditions and must be strictly distinguished from the critical shaft speeds resulting from static or dynamic unbalance of the rotating shaft.

       The critical speeds of trees are well known, but they have nothing in common with the critical speeds of nature that we have just considered. For each turbine wheel there are a considerable number of critical nodal speeds. Thus, there is, for example, a critical speed corresponding to the tendency of the wheel to vibrate in four radial nodes.

    and further - critical speeds identified by vibration trends corresponding to six knots, eight knots, ten knots, twelve knots etc .; for each key these tendencies there is a corresponding critical speed.

   It is therefore evident that, in consideration of the multiplicity (the critical speeds at which phenomena <the oscillations - can be generated in a - turbine disk, the proposal to change only 1 degree of rigidity of the turbine key wheel, would only result in creating new disturbances instead of avoiding them. turbations which one seeks to make say appear. In the course of the research which led to the present invention, repeated tests of this kind have in fact been unsuccessfully.

   Thus, for example, a large turbine had suffered key disturbances due to the tearing of blades. It was believed that by replacing the wheel with another wheel of a construction <B> more </B> s <B> -heavy, </B> the difficulty could be eliminated. The new impeller built according to these data, caused, shortly after the start of the turbine, (the new disturbance of a character worse than the first time.



   <B> On </B> the basis of the present invention, it is now known that, following the Bette modification of the dimensions, the different 1-
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   In some cases. it - will have some: speed, reviews above and a few below. speed (the uiarclle, and in other cases, which is preferable, <B> all </B> critical speeds are above normal speed (hopscotch.



       Wherever reference will be made, in the present specification, to the actual speeds of a turbine wheel or uil'rolor as being nearby (its normal hopscotch speed.

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       The vibratory tendencies (the impeller; with turbine, which lead to the production of oscillatory phenomena, must first be considered (given the relations which they produce when the impeller is at rest.

   The fi-. 8, 9, 10 and 11 represent photographic views of a turbine wheel ar row so as to show the production (the radial nmuds when; du'elle is put into vibration.

   The turbine wheel is shown in the rest state. In each case of the paper a. been extended over the part formed by the vanes and indicated by the ring-shaped parts 32. 33. 34 and 35. Dan. the fi ,, -. 111.

    the paper is shown as being removed by <B> 36 </B> in order to show the part formed by the albs: ininiédialenirnt in buttocks.



  In each example shown in FIGS. 8 to 11, an electromagnet is mounted on a support al) property not drawn near the turbine wheel.

   If an (, on- rani. Alternative (the arbitrary frequency is in-
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 <tb> i; (# onlétrlqu (: ^. <SEP> are <SEP> trained <SEP> by <SEP> a <SEP> rassem blenu'in <SEP> (the <SEP> _rains <SEP> <B> of </B> <SEP> charcoal <SEP> indicating <SEP> of
 <tb> points <SEP> <I> where </I> <SEP> the <SEP> wheel <SEP> is: <SEP> have <SEP> rest, <SEP> while <SEP> that
 <tb> the <SEP> r (#; gion:

    <SEP> (the <SEP> the <SEP> wheel. <SEP> (him <SEP> have <SEP> summer <SEP> rendered
 <tb> free. <SEP> (the <SEP> grains <SEP> of <SEP> coal, <SEP> match
 <tb> <B> went </B> <SEP> parties <SEP> in <SEP> <B> which ones </B> <SEP> (the <SEP> vibrations <SEP> se
 <tb> are <SEP> produced. <SEP> So <SEP> on <SEP> the <SEP> wheels <SEP> represented <SEP> in <SEP> (different <SEP> conditions <SEP> in <SEP> the <SEP> fi ,, -. <SEP> 8
 <tb> to <SEP> 11. <SEP> on <SEP> finds <SEP> (the <SEP> <B> confl \ gurations <SEP> or </B> <SEP> figures
 <tb> in <SEP> @raius <SEP> (1st <SEP> coal <SEP> showing <SEP> that. <SEP> clans
 <tb> the <SEP> case Respective <SEP>, <SEP> he <SEP> v <SEP> had <SEP> (lights <SEP> points <SEP> 39
 <tb> and <SEP> -10 <SEP> in <SEP> fi;

  . <SEP> 8, <SEP> oit <SEP> he <SEP> t- <SEP> had <SEP> for <SEP> so
 <tb> dil'e <SEP> point <SEP> (the <SEP> vibration., <SEP> slums <SEP> that ISL <SEP> the <SEP> fing. <SEP> 9
 <tb> he <SEP> t- <SEP> had <SEP> four <SEP> points <SEP> (the <SEP> rest <SEP> relative <SEP> -11 <SEP> to
 <tb> -1-1; <SEP> ('he <SEP> thread ,. <SEP> <B> 10 </B> <SEP> six <SEP> period. <SEP> (the <SEP> rest <SEP> relative <SEP> 45
 <tb> to <SEP> <B>) </B> tl. <SEP> and <SEP> fold <SEP> fi- <SEP> 11 <SEP> eight <SEP> points <SEP> (the <SEP> rest <SEP> relative <SEP> .51 <SEP> to <SEP>, i8. <SEP> These <SEP> points <SEP> can <SEP> be <SEP> (le <B> @ I @@ llt's <SEP> canteen <SEP> n (Puds <SEP> radial. </B>
 <tb>



  Bed <SEP> fi ;. <SEP> e <SEP> represents <SEP> by <SEP> consequent <SEP> a
 <tb> t ('udanee Vibratory <SEP> <SEP> rorrespoil (lant <SEP> to <SEP> two
 <tb> u (('ud #. <SEP> fig. <SEP> 9 <SEP> a <SEP> tendan (' Vibratory <SEP> <SEP> eorres-
EMI0008.0002
  
    laying <SEP> to <SEP> four <SEP> grinds, <SEP> the <SEP> fi-. <SEP> 10 <SEP> a <SEP> teil dance Vibratory <SEP> <SEP> corresponding <SEP> to <SEP> six <SEP> nodes,
 <tb> and <SEP> the <SEP> fig. <SEP> 11 <SEP> a <SEP> trend Vibratory <SEP> <SEP> corresponding <SEP> to <SEP> eight <SEP> nodes.

    <SEP> '. Fonts <SEP> these <SEP> figures <SEP> re present <SEP> different <SEP> conditions <SEP> of <SEP> the <SEP> same
 <tb> wheel <SEP> and <SEP> show <SEP> clearly <SEP> that a <SEP> same
 <tb> <B> wheel </B> <SEP> can <SEP> vibrate <SEP> <B> in <SEP> (lights <SEP> ilo'uds <SEP> or <SEP> four </B>
 <tb> <B> knots <SEP> or <SEP> six </B> <SEP> nodes <SEP> <B> or <SEP> eight <SEP> n # uds </B> <SEP> next
 <tb> the <SEP> frequency <SEP> of <SEP> vibration <SEP> to <SEP> <B> which </B> <SEP> the. <SEP> wheel
 <tb> is <SEP> submitted <SEP> by <SEP> the electromagnet <SEP> to <SEP> current
 alternative <tb> <SEP> or <SEP> (the other <SEP> force.

    Vibratory <SEP>.
 <tb> But <SEP> is <SEP> only <SEP> when <SEP> the <SEP> forces <SEP> vi bratory <SEP> exteriorcmellt <SEP> <B> applied </B> <SEP> enter
 <tb> (-il <SEP> resonance <SEP> with <SEP> the <SEP> trend Natural <SEP> <SEP> of
 <tb> vibration <SEP> of <SEP> the, <SEP> wheel, <SEP> that <SEP> these <SEP> trends <SEP> no dales <SEP> become <SEP> obvious.
 <tb>



  he <SEP> do <SEP> must <SEP> however <SEP> by <SEP> believe <SEP> that <SEP> the <SEP> roof (spear <SEP> of <SEP> the <SEP> wheel <SEP> (the <SEP> vibrate <SEP> in <SEP> n # uds <SEP> radials,
 <tb> when she <SEP> is <SEP> to <SEP> rest, <SEP> se <SEP> watch <SEP> in <SEP> the
 <tb> same <SEP> way <SEP> when <SEP> 1 <B> a </B> <SEP> wheel <SEP> is <SEP> in <SEP> rotation. <SEP> Like <SEP> he <SEP> a <SEP> summer <SEP> found. <SEP> he <SEP> se <SEP> product
 <tb> in <SEP> effect <SEP> a <SEP> action Extraordinary <SEP>. <SEP> Aux <SEP> speed <SEP> (the <SEP> rotation <SEP> to which <SEP> of <SEP> effects <SEP> of
 <tb> resonance <SEP> tend <SEP> to <SEP> se <SEP> produce <SEP> in <SEP> the
 <tb> wheel <SEP> same. <SEP> the <SEP> sections <SEP> <B> tick </B> <SEP> vibrations <SEP> no dales <SEP> (the <SEP> read.

    <SEP> wheel <SEP> binds <SEP> remain <SEP> not <SEP> fixed <SEP> clans
 <tb> ('gille-ci, <SEP> eainnie <SEP> reelected <SEP> (milks <SEP> the <SEP> fi-- <SEP> S <SEP> to
 <tb> <B> He. </B> <SEP> May; <SEP> doillieilt <SEP> location <SEP> to <SEP> the <SEP> liai- # ance <SEP> (oc @ il latiotis <SEP> nodals <SEP> molliles <SEP> (the <SEP> @, rand ('ur <SEP> considerable. <SEP> Like <SEP> eliaque <SEP> point <SEP> clans <SEP> the <SEP> rim <SEP> of
 <tb> the <SEP> wheel <SEP> is <SEP> period (liquenient <SEP> moved <SEP> of a
 <tb> side <SEP> to <SEP> the other <SEP> (the <SEP> the <SEP> wheel, <SEP> the <SEP> disturbance <SEP> is <SEP> transmitted <SEP> around <SEP> (the <SEP> the <SEP> wheel
 <tb> same <SEP> under <SEP> shape <SEP> of a <SEP> movement <SEP> on (1111 <ltoire.

    <SEP> The amplitude <SEP> (1st <SEP> in <SEP> iliolently <SEP> is <SEP> ao-randie <SEP> by <SEP> any <SEP> force <SEP> applied, <SEP> transmitted <SEP> from <SEP> outside <SEP> of <SEP> the <SEP> wheel
 <tb> in <SEP> resonance <SEP> on <SEP> approximately <SEP> in <SEP> re '#. sound <SEP> with <SEP> (the <SEP> series Wave <SEP> <SEP> phantom correspondent <SEP> ii. <SEP> a <SEP> period Natural <SEP> <SEP> (the <SEP> vibration
 <tb> <B> (l111 <SEP> would tend </B> <SEP>. <SEP> produce <SEP> (the <SEP> <B> 11 (111 (1s. </B> <SEP> Or <SEP> a
 <tb> found <SEP> (lapse <SEP> the <SEP> practical <SEP> (read, <SEP> polish <SEP> each
 <tb> (the <SEP> speeds <SEP> nodal:

    <SEP> critical, <SEP> he <SEP> y <SEP> a <SEP> a <SEP> os eillation <SEP> se <SEP> propagating <SEP> in <SEP> rear <SEP> (fans <SEP> the.
 <tb> rent <SEP> there. <SEP> the <SEP> same <SEP> speed <SEP> that <SEP> on <SEP> movement
 <tb> eyelash <SEP> before <SEP> (the <SEP> the <SEP> wheel. <SEP> and <SEP> by <SEP> this <SEP> done <SEP> oscillation <SEP> (becomes Stationary <SEP> <SEP> (lall:

    <SEP> space. <SEP> I? As
 <tb>; litlsi Stationary <SEP> <SEP> blanks <SEP> e # paee. <SEP> mowing The corresponding force or impulse there, the wheel from points outside of it, will act to continually increase the amplitude of the wheel. This is. A dangerous condition of the wheel. resonance.



       At the same time due to such stationary oscillations are produced there may be an oscillation propagating in the front wheel, possibly due to reflection. <B> of </B> the sorrelation e propagating in the wheel (, it back and caused by irregularities in the body * of the wheel,

   but practice has shown that such an oscillation is in general of negligible amplitude.



  When an oscillation propagating in the backward turbine wheel has been generated therein. a small portion of the energy (the reaction of the vapor is absorbed to produce and maintain this kind of bone.

   At the same time, the same energy <lo reaction (the vapor will tend to dampen the bone (forward motion once generated. A particular wheel of band diameter requires only. about an energy of <B> 80 </B> Watis to produce and maintain a vibration of a dangerous amplitude.

   In operation about t) 000 IiW of scared energy entered this stage of the turbine and about 1000 Ii 'remaining were ex pulsed.

       The springing effect of the vanes due to a backward oscillating movement causes a pulsating variation of the axial component <B> (the </B> the reactive energy of the vapor that is. in relation to direction and time. the same (read the natural period of the deckhouse:

       itself: for a forward oscillation. the pulsation would be the same with respect to time. but opposite, with respect to the direction. to the. pr: natural period of vibration and will therefore be damped by the action (the steam. A model of a steel wheel demonstrates this particular characteristic.

   This difference is there. relative size of the waves: propagating in the wheel in opposite directions. albeit at the same speed.

   could perhaps be explained with the aid of the mathematical conception that a periodic or alternative tiet -ion could be considered as the equivalent (the two oscillations of amplitudes equal:

  . but moving in opposite directions If, however, one (the oscillations are of a greater amplitude due to the other. there is a rotating effect.



  If. Therefore. (1P, force, exic1 # rely applied on a rotating turbine disk) <i resonate with any one of the disc's natural vibration periods. the tendency of the disc to vibrate will be <RTI

   ID = "0009.0131"> ercitée so as to cause what could be considered as the equivalent of two series of oscillations turning in opposite directions around <B> of </B> the wheel. If it happens that the period of natural vibration of the wheel is such that the waves moving backwards in the wheel come stationary in space. these motionless bones will be reinforced with each revolution (the wheel by the external force applied, by which the deflection of the wheel was caused.

   As a result of this resonance action. amplitude (the sagging becomes more and more brancid. Sticky to the wave train advancing in the same direction due to the wheel. no resonant action of this link reiire can develop and the linked wave train expands by therefore not if it is not put, as already, mentioned, into action to a lesser liking as a reflection of the uncle moving back.



  Uncles motionless in the wheel: of tur bine represent. a p-robressive bending of the wheel step by step. each point clans the periphery of the wheel following the movements of the mobile uncle when it passes through this point. At any given moment. the zero points of the waves can be represented by the nodal figures shown in fig: 8 <B> he, </B> 11.



  The bending of the. turbine wheel by these nodal oscillations tends. by walking (the long duration, to crystallize or tire <B> the </B> metal <B> (the </B> the wheel at the points where the greatest bending forces have been applied. This can, over time, produce a failure of the metal as it causes fractures.

   If the corresponding nodal figure extends deep into the wheel, the breaking points may occur far from the rim inside the wheel, while if the nodal figure. as in the case of a large number (the n (ruds, 11th does not extend deeply towards the axis of the wheel, the breaks will occur closer to the rim of the wheel.



  Now, it has been found that where phenomena of four-node oscillations occur, breaks generally appear in fine points closer to the axis of the wheel, while, when phenomena of oscillations of an order (the larger magnitudes are developed, the breaks are manifested closer (the rim of the wheel, or else only in the blades.

   A break due to a phenomenon of four-node oscillation is well illustrated in FIG. ? which shows a wheel with a break extending to point 6 deep into the wheel body. Note that in addition (the large broken section (the flange of the wheel, the blades have been torn from the rim of the wheel has point 60. In phis. We will notice the fine neighboring wheels 61, <B> 62) </B> and 63 were also seriously damaged, probably as a result of violent frictional action between the rims (the impellers, or the regions carrying the blades, and the stationary regions of the turbine.

    The turbine in which this accident happened had a power of 30,000 Ii.) The turbine and the alternator were demolished. A description in more detail is given in an article which appeared in the review entitled ..Po-, ver '& on November 2, 1921, pages 788 to 793. The September 3, 1918 issue of the same review described in pages 315 to 348 a similar accident occurred in a 35000 KW turbine in which a segment of approximately 100 kg was torn from the wheel of the 19th stage.



  Another example in which the production of immobile waves due to the phenomena (the oscillations flanks a turbine disk, caused the wheel to demolish, is shown in Fig. 6.

   In this case, the parts of, l The wheel, which had been broken into a large number of pieces, were picked up after the accident and put together to show where the lines <B> of </B> rupture had occurred. In this figure, the ruptured sections are indicated at 64, 65, 66 and 67. It will be appreciated that the ruptures extend through holes 24 and 5 and deep into the body of the. wheel.

   The rupture shown in this figure occurs in a turbine with a power of 10,000 IiW and included phenomena (oscillations at six knots.



  The thread-. 3 shows a sector torn from a wheel near the periphery, at 10, as a result of the action of a phenomenon of oscillation at four knots. It happened in this case, that the break went through holes 11 and 12 which were drilled one for the. receiving a threaded bolt (balancing and the other as pressure compensating opening to compensate for the pressure of the vapor on the heavens sides of the wheel disc.

   It is now evident that the rupture occurred at this point because the contour of the nodal fi-ure was: located so as to bring the region supporting the force. maximum in approximate coincidence with the. region fies holes supporting high stress.



  An explanation is provided by let fig. 9 showing the inner portion of the nodal figure extending far (the the inner periphery to 59.



  We believed in due time (such Tupturcs were (read it weakening (read disc of the wheel by the presence of trolls with their sharp edges) which. As we know, tend to localize (the efforts applied .

       1.1 is to be reill (lrquer, in passing, (read eoinnlc a (the inesure # suitable to avoid (the ruptures (the wheel., Great attention was devoted to the invention! @Ation of the effect (the trolls flans the disc (the wheel. the effect (the sharp edges etc.



       Models (the rubber wheels were executed with. Trolls. And set to high speed and. Examined with
EMI0011.0001
  
    the. <SEP> spokes <SEP> bright <SEP> key <SEP> periodicity <SEP> syn <B> chrone, </B> <SEP> On <SEP> a. <SEP> <B> pu <SEP> ain:

  l <SEP> determine, <SEP> a <SEP> help </B>
 <tb> of a <SEP> Surie <SEP> of <SEP> line, <SEP> crossed <SEP> marked <SEP> on
 <tb> the <SEP> wheel, <SEP> the <SEP> distortion <SEP> author <SEP> of <SEP> holes <SEP> clan
 <tb> the. <SEP> wheel. <SEP> (read <SEP> to <SEP> effort. <SEP> of <SEP> rotation. <SEP> The
 <tb> works <SEP> of <SEP> this <SEP> @ = <U> cure </U> <SEP> do <SEP> could <SEP> however
 <tb> not <SEP> give <SEP> unw <SEP> @solution <SEP> for <SEP> eliminate <SEP> these <SEP> dif fic # ttltais.
 <tb>



   <B> The <SEP> fitg. <SEP> -t <SEP> (.'t <SEP> J. <SEP> already <SEP> mentioned. <SEP> my- </B>
 <tb> trent <SEP> naked <SEP> example <SEP> clan. <SEP> which one. <SEP> under <SEP> action
 <tb> <B> (the </B> <SEP> plic @ noniénes <SEP> of oscillations. <SEP> of <SEP> dawn: <SEP> were
 <tb> <B> î </B> <SEP> rr- <SEP> completed <SEP> dune <SEP> wheel, <SEP> May:

    <SEP> in <SEP> which <SEP> the
 <tb> deterioration <SEP> do <SEP> turns off <SEP> not <SEP>, until <SEP> in <SEP> on
 <tb> body <SEP> <B> (the </B> <SEP> flaccid <SEP> of <SEP> the <SEP> wheel. <SEP> The <SEP> breaks
 <tb> (the <SEP> this <SEP> genre <SEP> there <SEP> are <SEP> due <SEP> to <SEP> closed <SEP> phenomena
 <tb> coseillations <SEP> cFun <SEP> order <SEP> of <SEP> size <SEP> superior. <SEP> (milks <SEP> which ones <SEP> the <SEP> figure <SEP> nodal <SEP> is
 <tb> onlyenieni. <SEP> produced <SEP> taken <SEP> or <SEP> in <SEP> the <SEP> portion
 <tb> eztérieurc @ <SEP> of <SEP> the <SEP> wheel. <SEP> like <SEP> specified. <SEP> by
 <tb> cxemplc #. <SEP> by <SEP> the <SEP> figure <SEP> to <SEP> eight <SEP> nauds <SEP> represented (@ <SEP> <B> in </B> <SEP> fiÏ. <SEP> 11.
 <tb>



  Of a <SEP> way General <SEP>. <SEP> the <SEP> disturbance
 <tb> by <SEP> o..c # illations <SEP> extends <SEP> as much <SEP> <B>]) III, ;; </B> <SEP> Profon dc-deny, <SEP> in <SEP> on <SEP> body <SEP> of <SEP> the <SEP> wheel. <SEP> due. <SEP> on
 <tb> number <SEP> of <SEP> ncruds <SEP> characterizing <SEP> on <SEP> plii @ nomèue
 <tb> of oscillations <SEP> is <SEP> plus:

    <SEP> small. <SEP> With <SEP> of <SEP> Folded nc> ntenes <SEP> of oscillations <SEP> of a <SEP> characteristic
 <tb> nodal <SEP> superior, <SEP> <B> the </B>. <SEP> disturbance <SEP> is <SEP> almost <SEP> surely <SEP> limited <SEP> to <SEP> areas <SEP> peripherals
 <tb> from <SEP> the <SEP> wheel.

    <SEP> He <SEP> in <SEP> results <SEP> that <SEP> the <SEP> more Serious <SEP>
 <tb> accidents <SEP> who <SEP> are <SEP> arrived <SEP> have <SEP> summer Said <SEP> <SEP> to <SEP> of
 <tb> phenomena <SEP> of oscillations <SEP> to <SEP> four <SEP> nccuds
 <tb> and <SEP> the <SEP> accidents <SEP> less <SEP> brave <SEP> to <SEP> of <SEP> folded nonienes Oscillation <SEP> <SEP> to <SEP> six <SEP> and <SEP> eight <SEP> grinds.
 <tb> Like <SEP> he <SEP> will be <SEP> explained <SEP> below, <SEP> of <SEP> phenomena <SEP> of oscillations <SEP> to <SEP> two <SEP> nodes <SEP> do <SEP> pro (glow <SEP> point Wave <SEP>: Stationary <SEP> <SEP> in <SEP> space <SEP> and <SEP> arrive <SEP> rarely. <SEP> fault <SEP> of <SEP> causes
 <tb> can <SEP> the <SEP> excite.
 <tb>



  To <SEP> of <SEP> determine <SEP> exactly <SEP> .the <SEP> speeds
 <tb> critical. <SEP> of a <SEP> wheel <SEP> of <SEP> turbine <SEP> and <SEP> for <SEP> be
 <tb> sure <SEP> that none <SEP> of <SEP> these <SEP> speeds <SEP> reviews <SEP> do <SEP> either
 <tb> to. <SEP> proximity <SEP> dangerous <SEP> of <SEP> the <SEP> speed <SEP> of
 <tb> walk <SEP> normal <SEP> of <SEP> the. <SEP> wheel <SEP> of <SEP> turbine, <SEP> on
 <tb> will have.

    <SEP> appeal <SEP> to <SEP> results <SEP> obtained <SEP> by <SEP> of
 <tb> tests <SEP> effective <SEP> (the <SEP> wheels <SEP> of <SEP> turbine Similar <SEP>.
 <tb> These <SEP> tests <SEP> are <SEP> of <SEP> nature <SEP> such <SEP> that they <SEP> don nent <SEP> exactly <SEP> the <SEP> phenomena <SEP> of oscilla-
EMI0011.0002
  
    tion, <SEP> ttyaiti, <SEP> link <SEP> clan, <SEP> iini, <SEP> wheel <SEP> of <SEP> turbine
 <tb> with <SEP> all <SEP> the <SEP> given. <SEP> required. <SEP> Ires <SEP> devices <SEP> employee: <SEP> to <SEP> this <SEP> effect <SEP> and <SEP> the <SEP> inc # thodes
 <tb> for <SEP> get <SEP> the <SEP> data <SEP> and <SEP> the <SEP> use <SEP> go
 <tb> now <SEP> be <SEP> described.
 <tb>



  The. <SEP> fig. <SEP> 1 ?. <SEP> done <SEP> next. <SEP> a <SEP> plioto; ra phy <SEP> with <SEP> some: <SEP> small <SEP> modifications <SEP> in si-nificantes. <SEP> represents <SEP> a <SEP> view <SEP> of a <SEP> my china <SEP> to <SEP> try <SEP> the <SEP> wheels <SEP> built <SEP> in <SEP> view
 <tb> from <SEP> the, <SEP> realization <SEP> of <SEP> improvement <SEP> next
 <tb> the invention. <SEP> This <SEP> niachin´ <SEP> includes <SEP> a <SEP> this is <SEP> <B> (the </B> <SEP> bedroom <SEP> test <SEP> armored, <SEP> clans <SEP> which <SEP> the <SEP> wheel <SEP> -t <SEP> try <SEP> is <SEP> bet <SEP> in <SEP> movement. <SEP> The. <SEP> half <SEP> superior <SEP> of <SEP> the envelope
 <tb> from <SEP> this <SEP> bedroom <SEP> test. <SEP> desired:

  born <SEP> by <SEP> 68,
 <tb> is <SEP> of <SEP> shape <SEP> semicircular <SEP>, and <SEP> is <SEP> formed
 <tb> from <SEP> fawn <SEP> to <SEP> constitute <SEP> a <SEP> cover <SEP> or <SEP> cover
 <tb> placing <SEP> above <SEP> (the <SEP> the <SEP> wheel <SEP> to <SEP> essayor.
 <tb> reads <SEP> regard <SEP> to <SEP> aoi-iclenis <SEP> possible. <SEP> this <SEP> by tie <SEP> must <SEP> be <SEP> extremely <SEP> solid, <SEP> of <SEP> way
 <tb> that she <SEP> do <SEP> will be <SEP> not <SEP> demolished <SEP> by <SEP> continued <SEP> of a
 <tb> aecidcnt. <SEP> arriving <SEP> to <SEP> the <SEP> wheel <SEP> to <SEP> try. <SEP> Dan:

  
 <tb> the <SEP> machine <SEP> illustrated, <SEP> this <SEP> cover <SEP> was <SEP> in <SEP> steel
 <tb> Boulé <SEP> of a <SEP> thickness <SEP> of <SEP>? 0f1 <SEP> mm <SEP> approximately.
 <tb> The. <SEP> part <SEP> lower <SEP> <B> 69 </B> <SEP> of <SEP> the <SEP> nutchine <SEP> who
 <tb> door <SEP> element <SEP> 61. <SEP> constitutes, <SEP> together <SEP> with
 <tb> of <SEP> parties <SEP> no <SEP> represented. <SEP> which ones <SEP> have
 <tb> not <SEP> need <SEP> to be <SEP> described <SEP> especially. <SEP> a
 <tb> bedroom <SEP> waterproof <SEP> to <SEP> the <SEP> steam.

    <SEP> A <SEP> part
 <tb> from <SEP> cover <SEP> 68 <SEP> is <SEP> represented <SEP> like <SEP> being <SEP> up <SEP> and <SEP> in <SEP> the opening <SEP> on <SEP> sees <SEP> a <SEP> wheel
 <tb> to <SEP> try <SEP> 70 <SEP> in <SEP> piston <SEP> for <SEP> the test <SEP> clan
 <tb> the, <SEP> bedroom.
 <tb>



  This <SEP> wheel <SEP> 70 <SEP> is <SEP> .monthly. <SEP> like <SEP> he <SEP> res sort <SEP> more <SEP> clearly <SEP> of <SEP> the <SEP> view <SEP> of <SEP> detail
 <tb> <U> fi-. </U> <SEP> 13. <SEP> on <SEP> the tree <SEP> 71. <SEP> in parallel <SEP> to <SEP> a
 <tb> disk <SEP> or <SEP> a <SEP> wheel <SEP> very Heavy <SEP> <SEP> and <SEP> practically <SEP> without <SEP> vibrations <SEP> 7 ?. <SEP> The tree <SEP> 71 <SEP> bearing
 <tb> the <SEP> wheels <SEP> 70 <SEP> and <SEP> 7? <SEP> is <SEP> arranged <SEP> of <SEP> way <SEP> to <SEP> to see <SEP> turn <SEP> to <SEP> any <SEP> speed <SEP> desired <SEP> to <SEP> help
 <tb> of a <SEP> source <SEP> of <SEP> force Appropriate <SEP>. <SEP> by <SEP> example <SEP> a <SEP> turbine <SEP> to <SEP> steam <SEP> <B> î3. </B>
 <tb>



  The <SEP> pipe <SEP> <B> 7 </B> <SEP> 4 <SEP> amine <SEP> of <SEP> the <SEP> steam <SEP> in <SEP> the
 <tb> bedroom <SEP> 68. <SEP> while <SEP> due <SEP> on <SEP> pipe <SEP> 75 <SEP> led
 <tb> the <SEP> steam <SEP> escape <SEP> to <SEP> the <SEP> pump <SEP> a, <SEP> empty
 <tb> and <SEP> to <SEP> condenser. <SEP> -A <SEP> pressure Absolute <SEP> About <SEP> <SEP> 0.33 <SEP> atm. <SEP> is <SEP> maintained <SEP> clans <SEP> the <SEP> room. <SEP> The <SEP> steam <SEP> in <SEP> the <SEP> bedroom <SEP> a. <SEP> for <SEP> goal
EMI0012.0001
  
    d (#. <SEP> maintain <SEP> reads <SEP> wheel <SEP> relatively <SEP> cold
 <tb> during <SEP> that she <SEP> is <SEP> submitted <SEP> to <SEP> the test, <SEP> too
 <tb> etran <SEP> ge <SEP> due <SEP> that <SEP> could <SEP> appear.

    <SEP> L <SEP> a <SEP> wheel
 <tb> 70 <SEP> is <SEP> bet <SEP> in <SEP> rotation <SEP> to <SEP> help <SEP> of <SEP> the <SEP> force
 <tb> from <SEP> of <SEP> the, <SEP> turbine <SEP> 73 <SEP> and <SEP> she <SEP> is not <SEP> not
 <tb> activated <SEP> ée <SEP> itself <SEP> of <SEP> way <SEP> to <SEP> produce
 <tb> from <SEP> energy, <SEP> neither <SEP> in <SEP> doing <SEP> pass <SEP> (the <SEP> the <SEP> steam
 <tb> to <SEP> through <SEP> the area <SEP> of <SEP> dawn. <SEP> neither <SEP> of a <SEP> other
 <tb> way. <SEP> If <SEP> however. <SEP> the <SEP> wheel <SEP> (stood up <SEP> turn
 <tb> (llinune <SEP> atmosphere <SEP> (air.

    <SEP> a <SEP> quantity <SEP> of
 <tb> heat <SEP> such <SEP> would be <SEP> en-endrée <SEP> by <SEP> lai <SEP> rotation
 <tb> violent <SEP> of <SEP> the <SEP> wheel <SEP> to <SEP> through <SEP> air <SEP> that <SEP> the
 <tb> temperature <SEP> of <SEP> the <SEP> wheel <SEP> would reach <SEP> a <SEP> degree
 <tb> dangerous. <SEP> The <SEP> temperature:

    <SEP> can <SEP> easily. <SEP> to rise <SEP> to <SEP> a <SEP> value <SEP> such <SEP> that <SEP> the <SEP> wheel.
 <tb> by <SEP> oxvclation. <SEP> becomes <SEP> bluish. <SEP> In <SEP> doing
 <tb> circulate <SEP> (the <SEP> the. <SEP> steam <SEP> dan. <SEP> the <SEP> bedroom <SEP> G8-69
 <tb> and <SEP> doing <SEP> evaeuel <SEP> this <SEP> steam <SEP> by <SEP> the <SEP> pump
 <tb> to <SEP> empty <SEP> and <SEP> on <SEP> condenser <SEP> (no <SEP> shown),
 <tb> the energy:, laughs <SEP> (the <SEP> heat <SEP> generated <SEP> by <SEP> the <SEP> rotation <SEP> (the <SEP> the <SEP> wheel <SEP> is <SEP> removed <SEP> and <SEP> the <SEP> temperature
 <tb> from <SEP> the <SEP> wheel <SEP> maintained <SEP> clans <SEP> the limits <SEP> of <SEP> security.
 <tb>



  To <SEP> to observe <SEP> and <SEP> cl'enr (# 1istrer <SEP> the <SEP> movement: Wave <SEP> <SEP> or <SEP> vibration. <SEP> can <SEP> se
 <tb> produce <SEP> dails <SEP> the <SEP> wheel <SEP> (the ezzs # ai. <SEP> all <SEP> means
 <tb> appropriate., <SEP> can <SEP> be <SEP> emplovi's. <SEP> On <SEP> can
 <tb> employ <SEP> to <SEP> this <SEP> effect <SEP> the <SEP> oseillograplies <SEP> good
 <tb> known <SEP> in <SEP> the (#troteelinidue <SEP> together <SEP> with
 <tb> (the <SEP> coils <SEP> test <SEP> housed <SEP> of <SEP> way <SEP> appropriate <SEP> in <SEP> on <SEP> body <SEP> (the <SEP> the. <SEP> machine <SEP> to <SEP> try
 <tb> the. <SEP> wheels <SEP> represented <SEP> in <SEP> fi \ ;. <SEP> 1 ?. <SEP> Two <SEP> groups
 <tb> from <SEP> coil:

    <SEP> from e..ai <SEP> are <SEP> employees. <SEP> The <SEP> coils
 test <tb> <SEP> (one <SEP> #, - roitpe <SEP> are. Stationary <SEP> <SEP> by
 <tb> report <SEP> to <SEP> reads <SEP> wheel <SEP> who <SEP> must <SEP> be <SEP> tried. <SEP> tan (read <SEP> due <SEP> that. <SEP> (the <SEP> the other <SEP> group <SEP> turn <SEP> with
 <tb> lai. <SEP> wheel. <SEP> LTlie <SEP> (the <SEP> coils <SEP> test <SEP> stations <SEP> or <SEP> fixed <SEP> is <SEP> specified <SEP> seen <SEP> <B> 76 </B> <SEP> to <SEP> the <SEP> fig. <SEP> 13
 <tb> and <SEP> schematically <SEP> in <SEP> <B> 76 </B> <SEP> to <SEP> the <SEP> fig. <SEP> <B> 16. </B> <SEP> A
 <tb> (the <SEP> coils <SEP> rotary <SEP> is <SEP> specified <SEP> (# 11 <SEP> 7 <SEP> ï <SEP> to
 <tb> the <SEP> fi-. <SEP> 13 <SEP> and.

    <SEP> more <SEP> in <SEP> detail <SEP> in <SEP> <B> 77 </B> <SEP> <1 <SEP> the <SEP> fig. <SEP> 1-1
 <tb> and <SEP> scliematiduenient <SEP> in <SEP> 7 <SEP> 7 <SEP> to <SEP> the <SEP> fi ;. <SEP> 1 (j. <SEP> These
 <tb> coil. <SEP> test <SEP> transmit <SEP> of <SEP> imaces
 <tb> electric <SEP> of <SEP> movement <SEP> of <SEP> the <SEP> wheel <SEP> (the <SEP> tur bine <SEP> <B> to <SEP> oa'lllograpllt's <SEP> (1l11 <SEP> 1l # 3 <SEP> save. </B>
 <tb>



  The ace <SEP> coil Stationary <SEP> <SEP> <B> 76 </B> <SEP> transmits <SEP> a
 <tb> iniare <SEP> (the <SEP> movements <SEP> of <SEP> each <SEP> point <SEP> in
 <tb> lai <SEP> periphery <SEP> (the <SEP> reads <SEP> wheel <SEP> #e <SEP> bringing together <SEP> and
EMI0012.0002
  
    'el () l @ rllflllt <SEP> key <SEP> the <SEP> coil <SEP> (the test. <SEP> when <SEP> the
 <tb> wheel <SEP> payse <SEP> in front <SEP> this <SEP> coil. <SEP> The <SEP> coil
 <tb> mobile <SEP> <B> 77 </B> <SEP> who <SEP> turns <SEP> with <SEP> the <SEP> wheel <SEP> siir <SEP> the other
 <tb> side. <SEP> save <SEP> on <SEP> movement <SEP> lateral <SEP> of a
 <tb> point <SEP> given <SEP> only <SEP> in <SEP> the <SEP> circumference
 <tb> from <SEP> the <SEP> wheel.

    <SEP> The <SEP> records <SEP> of <SEP> these <SEP> two
 <tb> coils <SEP> indicate <SEP> the <SEP> nature <SEP> (the <SEP> phenomena
 <tb> cl'o, cillatiolis <SEP> developed <SEP> in <SEP> the <SEP> wheel.
 <tb>



  The <SEP> coils <SEP> (the test <SEP> who <SEP>: have <SEP> lo-gées <SEP> (without
 <tb> the <SEP> bedroom <SEP> of <SEP> the <SEP> machine <SEP> to <SEP> try <SEP> the <SEP> wheel
 <tb> are Waterproof <SEP> <SEP> to <SEP> the <SEP> steam. <SEP> In <SEP> <B> (the </B> <SEP> goal. <SEP> the
 <tb> coils <SEP> can <SEP> be <SEP> completely <SEP> hell meses <SEP> in <SEP> a <SEP> box <SEP> metallic <SEP> (the <SEP> way <SEP> to
 <tb> prevent <SEP> access <SEP> of <SEP> the <SEP> steam. <SEP> In <SEP> fig. <SEP> <B> I <SEP> -L </B>
 <tb> the <SEP> coil <SEP> 77 <SEP> is <SEP> represented <SEP> coninie <SEP> being
 <tb> climb <SEP> in <SEP> the end <SEP> of <SEP> tube <SEP> ï <SEP> 8 <SEP> in <SEP> my <SEP> magnetic.

    <SEP> A <SEP> plate <SEP> (the <SEP> cover
 <tb> (9 <SEP> in <SEP> brass <SEP> (read <SEP> material <SEP> ailillU-tle <SEP> shutter
 <tb> the opening <SEP> in <SEP> which <SEP> the <SEP> coil <SEP> <B> 4-7 </B> <SEP> (-st
 <tb> outfit <SEP> and <SEP> this <SEP> last <SEP> is <SEP> <B> maintained </B> <SEP> in <SEP> place.
 <tb> by <SEP> on <SEP> bolt <SEP> <B> the S </B> O <SEP> in <SEP> material <SEP> niaunétidue <SEP> for mant <SEP> on <SEP> iloyed <SEP> of <SEP> the <SEP> coil <SEP> <B> 77. </B> <SEP> The <SEP> thread <SEP> in closed <SEP> in <SEP> luxury <SEP> (taunts <SEP> 111éta111qn2 <SEP> 81 <SEP> on <SEP> a
 <tb> other <SEP> thread <SEP> eoilclucteur <SEP> isolated <SEP> electrically <SEP> and
 <tb> protected <SEP> against <SEP> reads <SEP> waltzer <SEP> goes out <SEP> of <SEP> connection
 <tb> electric <SEP> to <SEP> the <SEP> coil.
 <tb>



  The <SEP> <B> support <SEP> tubular <SEP> (1 </B> <SEP> (## t <SEP> tn @, ul @ #. <SEP> t @@ nlme
 <tb> represented <SEP> to <SEP> fi, - ,,. <SEP> 1; <SEP> and <SEP> 11. <SEP> 11a11: <SEP> lin
 <tb> (moon <SEP> projection <SEP> of <SEP> ft @ ra @; e
 <tb> the <SEP> periphery <SEP> <B> of </B> <SEP> the <SEP> wheel
 <tb> 7 <SEP> 2 <SEP> and <SEP> can <SEP> be <SEP> at, Jll.té <SEP> eu <SEP> direetlon <SEP> axial <SEP> (the
 <tb> the <SEP> wheel <SEP> and <SEP> held <SEP> in <SEP> place <SEP> by <SEP> the <SEP> lock nuts
 <tb> 82.

    <SEP> The <SEP> ext. <SEP> exterior <SEP> (read <SEP> support
 <tb> tubular <SEP> (8 <SEP> are <SEP> staves <SEP> by <SEP> the <SEP> consoles
 <tb> 83 <SEP> and <SEP> <B> 81. </B> <SEP> The <SEP> thread <SEP> driver <SEP> prott> ge <SEP> 81 <SEP> is
 <tb> posed <SEP> on <SEP> long <SEP> of <SEP> side <SEP> of <SEP> the <SEP> wheel <SEP> 72 <SEP> and <SEP> goes out
 <tb> by <SEP> the tree <SEP> like <SEP> indicated <SEP> eil <SEP> <B> 85- </B>
 <tb> He <SEP> is <SEP> indicated <SEP> (have it <SEP> in <SEP> reserve. <SEP> in <SEP> ras
 <tb> from <SEP> disturbances <SEP> of <SEP> reads <SEP> coil <SEP> 7 <SEP> 7 <SEP> and <SEP> (the <SEP> sound
 <tb> circuit. <SEP> a <SEP> coil <SEP> (the test <SEP> rotary <SEP> additional <SEP> located <SEP> in <SEP> 8 ( <B>) </B> <SEP> in <SEP> a <SEP> location <SEP> diametrically <SEP> opposite.

    <SEP> This <SEP> coil <SEP> aillai <SEP> (kill <SEP> s (#s <SEP> sup ports <SEP> and <SEP> connections <SEP> are <SEP> seil: ilcleinelit <SEP> the
 <tb> same <SEP> (111th <SEP> in <SEP> on <SEP> eas <SEP> (the <SEP> the <SEP> bulline <SEP> <B> 77. </B> <SEP> The
 <tb> drivers <SEP> of <SEP> each <SEP> coil <SEP> are <SEP> anlenéS
 <tb> together <SEP> have <SEP> outside <SEP> to <SEP> through <SEP> the tree <SEP> in <SEP> <B> 85. </B>
 <tb> A <SEP> thread <SEP> (the <SEP> each <SEP> coil <SEP> is <SEP> 1 - (# (111i <SEP> to <SEP> a <SEP> driver Common <SEP>.

    <SEP> and <SEP> the <SEP> three <SEP> driver.
 <tb> are <SEP> then <SEP> connected <SEP> to <SEP> (the <SEP> rings <SEP> collection
EMI0013.0001
  
    trices <SEP> <B> 87 </B> <SEP> and <SEP> of <SEP> brooms <SEP> 88 <SEP> on <SEP> the end
 <tb> 1ilare <SEP> of <SEP> the tree <SEP> like <SEP> represented <SEP> e11 <SEP> thread. <SEP> 1.
 <tb>



  The <SEP> wheel <SEP> who <SEP> must <SEP> be <SEP> tried, <SEP> by <SEP> exem pla. <SEP> the <SEP> rottu <SEP> ï (). <SEP> <B> is </B> <SEP> placed <SEP> by <SEP> report <SEP> to <SEP> the
 <tb> ljobine <SEP> 7 <SEP> (the <SEP> way <SEP> such <SEP> that a <SEP> portion <SEP> of
 <tb> the <SEP> wheel <SEP> ('this <SEP> clans <SEP> on <SEP> neighborhood <SEP> llnlnédlat <SEP> (read
 <tb> ovau <SEP> contrai <SEP> SU <SEP> and <SEP> of <SEP> the. <SEP> wall <SEP> magnetic
 <tb> purring <SEP> a <SEP> part <SEP> of <SEP> circuit <SEP> magnetic
 <tb> (1 (. <SEP> the <SEP> coil <SEP> <B> 77. </B> <SEP> In <SEP> some <SEP> case, <SEP> the <SEP> wheel
 <tb> :( <SEP> e .:

  say <SEP> small <SEP> have <SEP> of <SEP> such <SEP> dimensions
 <tb> (p (v <SEP> 1st <SEP> bandage <SEP> or <SEP> recovery <SEP> (the <SEP> vanes
 <tb> is <SEP> in <SEP> face <SEP> of <SEP> the <SEP> coil <SEP> <B> 77; </B> <SEP> but <SEP> clans <SEP> the
 <tb> most <SEP> due <SEP>, as <SEP> the <SEP> dimensions <SEP> of <SEP> the <SEP> wheel <SEP> to
 <tb> (# @:

  aVer <SEP> shot. <SEP> pernivitent <SEP> not <SEP> this <SEP> layout.
 <tb> In <SEP> this <SEP> eas, <SEP> he <SEP> e-t <SEP> indicated, <SEP> like <SEP> shown
 <tb> in <SEP> fig. <SEP> 15. <SEP> of <SEP> solder, <SEP> or <SEP> (attach it <SEP> of a
 <tb> other <SEP> way Appropriate <SEP>, <SEP> to <SEP> a <SEP> section
 <tb> (dawn <SEP> 89 <SEP> of <SEP> the. <SEP> wheel, <SEP> a <SEP> reinforcement <SEP> 90 <SEP> in
 <tb> material <SEP> magnetic <SEP> placed <SEP> of <SEP> way <SEP> to <SEP> be
 <tb> dircrtenient <SEP> in <SEP> face <SEP> (the <SEP> the <SEP> coil <SEP> <B> î7. </B> <SEP> Lvidem mont. <SEP> a <SEP> armor <SEP> similar <SEP> is <SEP> planned
 <tb> lim (r <SEP> read <SEP> (#:

  ( <B> (1st </B> <SEP> the <SEP> coil <SEP> SG. <SEP> For <SEP> the <SEP> two
 <tb> l) (jblilv = <SEP> 7 <SEP> 7 <SEP> and <SEP> <B> 86, </B> <SEP> the <SEP> layout <SEP> is <SEP> chosen
 <tb> key <SEP> mali @ re <SEP> to <SEP> leave <SEP> a <SEP> space <SEP> appropriate
 <tb> (-litre <SEP> read <SEP> coils <SEP> and <SEP> their <SEP> reinforcements <SEP> respec tives. <SEP> The <SEP> game <SEP> is <SEP> usually <SEP> of <SEP> 3 <SEP> to <SEP> 10 <SEP> mm
 <tb> approximately <SEP> for <SEP> the <SEP> large <SEP> wheels <SEP> and <SEP> less
 <tb> for <SEP> on: <SEP> small.
 <tb>



  he <SEP> must <SEP> mention <SEP> (read <SEP> the <SEP> coil <SEP> test
 <tb> fixed <SEP> ï <SEP> (i <SEP> sus <SEP> specified <SEP> is <SEP> fixed <SEP> (the <SEP> way <SEP> appropriate <SEP> (fans <SEP> on <SEP> cover <SEP> 68 <SEP> to <SEP> neighborhood <SEP> of
 <tb> edge <SEP> of <SEP> the <SEP> wheel, <SEP> good <SEP> that <SEP> this <SEP> do <SEP> either <SEP> not
 <tb> represented <SEP> have <SEP> drawing, <SEP> and <SEP> that <SEP> in <SEP> this <SEP> case. <SEP> he
 <tb> have <SEP> also <SEP> a <SEP> coil <SEP> of <SEP> reserve <SEP> 93
 <tb> diametrically <SEP> opposite <SEP> (fi ,. <SEP> 16) <SEP> and <SEP> also <SEP> placed <SEP> in <SEP> on <SEP> cover, <SEP> the <SEP> two <SEP> coils
 <tb> being <SEP> linked (: <SEP> of <SEP> way Appropriate <SEP> <SEP> by <SEP> of
 <tb> connection:

    <SEP> electric <SEP> like <SEP> represented <SEP> in
 <tb> fi, .. <SEP> l (;. <SEP> The <SEP> coils Stationary <SEP> <SEP> on <SEP> fixed
 <tb> <B> 76 </B> <SEP> and <SEP> <B> 93 </B> <SEP> are <SEP> housed <SEP> each, <SEP> like <SEP> the <SEP> bo bine <SEP> rotary <SEP> <B> 77, </B> <SEP> in <SEP> a <SEP> box <SEP> in <SEP> material
 <tb> magnetic <SEP> for <SEP> constitute <SEP> a <SEP> circuit <SEP> my glietic <SEP> open <SEP> like <SEP> in <SEP> on <SEP> case <SEP> (the <SEP> the
 <tb> coil <SEP> rotary <SEP> <B> 77. </B>
 <tb>



  To <SEP> (the <SEP> power <SEP> produce <SEP> to <SEP> will <SEP> a
 <tb> vibration <SEP> of <SEP> the <SEP> wheel Test <SEP>, <SEP> on <SEP> a <SEP> courtyard <SEP> a
 <tb> electromagnet <SEP> 91 <SEP> good <SEP> isolated <SEP> indicated <SEP> in <SEP> fi-. <SEP> 1
 <tb> and. <SEP> (-il <SEP> quickly <SEP> perspective, <SEP> in <SEP> fig. <SEP> 1 ?. <SEP> This <SEP> electromagnet is placed in front of the periphery of the wheel. as shown and suitably connected to a source (the current, as indicated in 9? (fio ;. 16). 011 will note that the electromagnet 91 is inside said cover 68.



       The electrical connections of the different test coils etc. the electrical circuits (the amplifiers, (the oscillographs and (the magnet t11., Are shown schematically in fig.- lti. In this figure, the. Wheel ( the test is indicated.

   for clarity, (the conventional way in <B> 70 </B> and the ri- gidG disk <B> 72 </B> is also represented conventionally and abnormally (lél> laced laterally, so that the circuits are more clearly visible.

   The conductors (the rotating coils 7 7 and <B> 86 </B> exit through the tree at 8; i and are connected to the ba-uej collevtriceâ <B> 87 </B> with the brushes 88 which are connected to the primary terminals 94 of a transformer. A switch 195 allows you to switch it on at will. <B>, </B> coil <B> 77. </B> or the coil 86. The current of a source <B> (the </B> current.

   continuous 1,16 passes normally through one or the other (the rotating coils î ï or <B> 86. </B> It is obvious that only one of these coils is used for the tests and that only in the event of an accident.



  Similarly, stationary coils 7 6 and 93 are connected by the switch <B> 97 </B> to the primary terminals 98 of a transformer. The switch <B> 97 </B> allows, as above, the use of one or the other (the two coils.

   A battery 99 supplies (read direct current to that of these coils which is damaged in circuit by the switch <B> 97. </B> The secondary windings 100, <B> 101, </B> corresponding to the two primary windings; 94 and 98, are connected respectively to (the appropriate amplifying devices to reinforce the fluctuations in rant produced by the action (the testing wheel firing the test coils; for example 77 and 76.



  It will be understood that the current, in these coil- (the test, coming from the 9G batteries and
EMI0014.0001
  
    99, <SEP> develops <SEP> a <SEP> field Magnetic <SEP>, <SEP> of which
 <tb> the, <SEP>;

    <SEP> reeler <SEP> varies <SEP> in <SEP> dependency <SEP> of <SEP> variations <SEP> (the <SEP> the <SEP> width <SEP> of <SEP> the air gap <SEP> between <SEP> the
 <tb> parties Adjacent <SEP> <SEP> of <SEP> the <SEP> wheel <SEP> and <SEP> the <SEP> circuits
 magnetic <tb> <SEP> of <SEP> coils. <SEP> In <SEP> on <SEP> case <SEP> of <SEP> the
 <tb> coil <SEP> rotary <SEP> 77, <SEP> the <SEP> vibration Lateral <SEP> <SEP> (the
 <tb> the <SEP> part <SEP> adjacent <SEP> of <SEP> the <SEP> wheel <SEP> product <SEP> a
 <tb> change <SEP> of <SEP> the <SEP> resistance Magnetic <SEP>,
 <tb> while <SEP> that <SEP> clans <SEP> on <SEP> case <SEP> of <SEP> the <SEP> coil <SEP> stationary.

    <SEP> by <SEP> example <SEP> <B> 76, </B> <SEP> on <SEP> change <SEP> of <SEP> the
 <tb> resistance <SEP> niaenetics <SEP> is <SEP> product <SEP> by <SEP> of
 <tb> variations <SEP> clans <SEP> the <SEP> distance. <SEP> and <SEP> so <SEP> of <SEP> remains,
 <tb> from <SEP> edge <SEP> of <SEP> the <SEP> wheel <SEP> when <SEP> path <SEP> close
 <tb> from <SEP> the. <SEP> coil Stationary <SEP>. <SEP> These <SEP> variations <SEP> of
 <tb> distance <SEP> are <SEP> in <SEP> part <SEP> due <SEP> to <SEP> irregularities <SEP> of <SEP> body <SEP> of <SEP> the <SEP> wheel <SEP> same <SEP> and, <SEP> in <SEP> case <SEP> (the
 <tb> phenomena <SEP> of oscillations. <SEP>; L <SEP> (the <SEP> sagging <SEP> side <SEP> <B> (the </B> <SEP> the. <SEP> wheel.
 <tb>



  Of <SEP> circuits <SEP> amplifiers <SEP> are <SEP> connec ted <SEP> to <SEP> secondary <SEP> 100 <SEP> and <SEP> 101. <SEP> From <SEP> similar
 <tb> circuits <SEP> amplifiers <SEP> are <SEP> good <SEP> known <SEP> in
 <tb> electrical engineering <SEP> and <SEP> binds <SEP> require <SEP> point <SEP> of
 <tb> description <SEP> special. <SEP> The <SEP> tube <SEP> amplifier
 <tb> from <SEP> circuit <SEP> multiplier <SEP> connected <SEP> year <SEP> secon (laire <SEP> 1tiÙ <SEP> and <SEP> designated <SEP> by <SEP> 1t) 21. <SEP> He <SEP> includes
 <tb> 11n <SEP> tube <SEP> evacuated <SEP> provided <SEP> (Finished <SEP> cathode <SEP> fairy chauf <SEP> 103. <SEP> of a <SEP> plate <SEP> or <SEP> ailocle <SEP> 104 <SEP> and <SEP> of a
 <tb> 7rilie <SEP> 105.

    <SEP> A <SEP> battery <SEP> 106 <SEP> provides <SEP> on <SEP> current <SEP> for <SEP> the <SEP> cathode <SEP> 103 <SEP> and <SEP> a <SEP> rheostat <SEP> 107
 <tb> serves <SEP> to <SEP> set <SEP> on <SEP> current <SEP> in <SEP> on <SEP> filament
 <tb> cathodic. <SEP> A <SEP> circuit <SEP> connect <SEP> the <SEP> plate
 <tb> 10.1 <SEP> with <SEP> lai <SEP> cathode <SEP> 103 <SEP> to <SEP> through <SEP> a <SEP> source
 <tb> from <SEP> current <SEP> <B> 108 </B> <SEP> and <SEP> in <SEP> ee <SEP> circuit <SEP> is <SEP> con nected <SEP> on <SEP> primary <SEP> 109 <SEP> (one <SEP> transformer,
 <tb> including <SEP> on Secondary <SEP> <SEP> 110 <SEP> is <SEP> connected <SEP> to <SEP> oseillo gi'aplles,

    <SEP> like <SEP> that <SEP> will be <SEP> described <SEP> more <SEP> away.
 <tb> A <SEP> battery <SEP> 111 <SEP> (the <SEP> qiielqiifes <SEP> volts <SEP> is <SEP> placed
 <tb> in <SEP> on <SEP> eireuit <SEP> (the <SEP> the <SEP> grid. <SEP> co-mnie <SEP> shown,
 <tb> for <SEP> give <SEP> î1 <SEP> the <SEP> grid <SEP> a <SEP> load <SEP> negative.
 <tb>



  The <SEP> operation <SEP> of <SEP> amplifier
 <tb> dc <SEP> this <SEP> genre <SEP> is <SEP> good <SEP> known. <SEP> Of <SEP> fluctuations
 <tb> (the <SEP> t (#nsioli <SEP> produced <SEP> (1a11 .. <SEP> on Secondary <SEP> <SEP> I0t)
 <tb> are <SEP> transmitted <SEP> to <SEP> the <SEP> @grid <SEP> 105, <SEP> and <SEP> the <SEP> clian 7elllellts <SEP> <B> (read </B> <SEP> potential <SEP> in <SEP> the. <SEP> grid <SEP> provoking <SEP> (l (. <B> #z </B> <SEP> ellall1 - ('litc'ilts <SEP> a_-rall ($ 11 <SEP> (111 <SEP> current
 <tb> passing. <SEP> in <SEP> on <SEP> cirt'nit <SEP> of <SEP> the <SEP> plate <SEP> <B> 101, </B> <SEP> These
 <tb> <B> ehall_-enleilt @ <SEP> of <SEP> ('ourallt: <SEP>: If @ 'all (11:

    <SEP> jlt'odulse (it </B>
EMI0014.0002
  
    of <SEP> fluctuations <SEP> of <SEP> current Corresponding <SEP>
 <tb> in <SEP> on Secondary <SEP> <SEP> 110 <SEP> connected <SEP> to <SEP> oscillo graphs.
 <tb>



  The Secondary <SEP> <SEP> 101 <SEP> (111 <SEP> transformer
 <tb> who <SEP> is <SEP> connected <SEP> with <SEP> the <SEP> coil <SEP> test <SEP> <B> 76, </B>
 <tb> is <SEP> provided <SEP> of <SEP> way <SEP> analogue <SEP> of a <SEP> cir cuit <SEP> amplifier <SEP> in <SEP> which <SEP> on <SEP> tube <SEP> amplifier <SEP> is <SEP> designated <SEP> by <SEP> 11 ?. <SEP> on <SEP> filament
 <tb> cathodic <SEP> by <SEP> 113, <SEP> the ano (the <SEP> have <SEP> plate <SEP> by
 <tb> lld <SEP> and <SEP> the <SEP> grid <SEP> by <SEP> 11:

  1. <SEP> 1 \ 11th <SEP> battery <SEP> 116
 <tb> with <SEP> the <SEP> resistance <SEP> adjustable <SEP> 117 <SEP> serves <SEP> to <SEP> iron heater <SEP> on <SEP> filament <SEP> to <SEP> degree <SEP> wanted. <SEP> A <SEP> bat terie <SEP> 118 <SEP> for <SEP> give <SEP> to <SEP> the <SEP> grid <SEP> a <SEP> load
 <tb> negative, <SEP> is <SEP> connected <SEP> in <SEP> on <SEP> circuit <SEP> of
 <tb> grid <SEP> like <SEP> above. <SEP> The <SEP> circuit <SEP> of <SEP> plate
 <tb> from <SEP> this <SEP> amplifier <SEP> is: <SEP> provided <SEP> of <SEP> the <SEP> source
 <tb> from <SEP> current <SEP> 119 <SEP> and <SEP> includes <SEP> on <SEP> primary <SEP> 12 (1l
 <tb> of a <SEP> transformer. <SEP> of which <SEP> read <SEP> s (#conclude <SEP> 121
 <tb> is <SEP> also <SEP> connected <SEP> to <SEP> oscillograp11e5
 <tb> above.
 <tb>



  The <SEP> oseillograplies <SEP> indicated <SEP> sclienlatiqiie ment <SEP> in <SEP> the <SEP> part <SEP> sup (: rieiire <SEP> of <SEP> the <SEP> fig. <SEP> 1t;
 <tb> are <SEP> of <SEP> instruments <SEP> normal <SEP> good <SEP> known
 <tb> in <SEP> electrical engineering, <SEP> for <SEP> produce <SEP> and <SEP> for
 <tb> save <SEP> (the <SEP> images <SEP> representative <SEP> the <SEP> fluc kills Instant <SEP> <SEP> in <SEP> instant <SEP> of <SEP> current
 <tb> electric .. <SEP> These <SEP> images <SEP> pcitvent <SEP> to be <SEP> products <SEP> by <SEP> the <SEP> trace <SEP>! 1 '(11i <SEP> hairy <SEP> lllinilleux <SEP> on
 <tb> a <SEP> screen, <SEP> or <SEP> the <SEP> images <SEP> petivelit <SEP> be <SEP> registered <SEP> of <SEP> way Permanent <SEP> <SEP> on <SEP> a <SEP> rope
 photographic <tb>.

    <SEP> Of <SEP> oscillographs <SEP> of <SEP> this
 <tb> genre <SEP> are, <SEP> by <SEP> example, <SEP> described <SEP> in <SEP> a
 <tb> article <SEP> on <SEP>, .The <SEP> Oscillographs <SEP> and <SEP> their <SEP> Employment " <SEP> by <SEP> Lewis <SEP> T. <SEP> Robinson, <SEP> in <SEP> the
 <tb> I transactions <SEP> of <SEP> tlie <SEP> _liiieri (#an <SEP> Institute <SEP> of
 <tb> Electrical <SEP> Eii-iiie (#rs ", <SEP>? <B> 8 </B> <SEP> April <SEP> <B> 1905. </B> <SEP> Vol.
 <tb> ZZIV. <SEP> pages <SEP> '185 <SEP> to <SEP> \? 1-.1.
 <tb>



  lease; <SEP> the <SEP> fig <SEP> 1! I, <SEP> r <'prt @ .: enlani
 <tb> ment-, <SEP> two <SEP> of <SEP> these <SEP> instrti (ilenis. <SEP> the <SEP> tIertro magnets <SEP> of <SEP> ellamp <SEP> (1'11n <SEP> of <SEP> osoillograplies
 <tb> <B> ç <SEP> (111 <SEP> eoil- </B>
 <tb> have <SEP> keysi <SEP> <B> <U> gliés </U> </B> <SEP> by <SEP> <B> II # z </B>
 <tb> rant. <SEP> to <SEP> through <SEP> closed <SEP> (lialu.:itii ::

    <SEP> (the <SEP> setting <SEP> of
 <tb> <B> ('ocrant <SEP> 1l (111 <SEP> (1'1111c ' <SEP> s (1111 '(' (! <SEP> (1 (' </B>
 <tb> ooitraiit <SEP> eoiltiiiu <SEP> atlprt (i> rit @ t # <SEP> in (liqti (- (# <SEP> 11; 1r <SEP> l # @ ç
 <tb> leagues <SEP> (the old @ e <SEP> of <SEP> ('onr; int. <SEP> 12: 3. <SEP> For <SEP> olia cun <SEP> of <SEP> (# loetro-ainlailis <SEP> 1_22l. <SEP> he <SEP> y <SEP> a <SEP> uiie <SEP> sort
 <tb> from <SEP> suspension <SEP> two-wire <SEP> <B> 12f. </B> <SEP> 12 <B>) </B> <SEP> and <SEP> 1-t1.
 <tb> pectiveinent, <SEP> betting <SEP> (#oninle <SEP> (the liabiitttlo <SEP> him
EMI0015.0001
  
    small <SEP> mirror. <SEP> The <SEP> light <SEP> from <SEP> of a <SEP> source
 <tb> bright Appropriate <SEP>. <SEP> by <SEP> example <SEP> of a
 <tb> lainpv <SEP> to <SEP> arc <SEP> no <SEP> repr ,:

  # cntec. <SEP> is <SEP> transmitted
 <tb> <B> a </B> <SEP> through <SEP> a <SEP> lens <SEP> <B> 12Î </B> <SEP> and <SEP> a <SEP> prism <SEP> <B> l28 <SEP> "_ </B>
 <tb> to <SEP> cc: <SEP> mirror. <SEP> el <SEP> reflectec <SEP> on <SEP> of <SEP> surfaces <SEP> of,
 <tb> rt # @ elition <SEP> appropriate :. <SEP> In <SEP> on <SEP> present <SEP> excluded plus. <SEP> these <SEP> e-onsistent <SEP> eyelash <SEP> a <SEP> mirror <SEP> oscil lant <SEP> <B> 1_l9 </B> <SEP> arran !, h <SEP> of <SEP> way <SEP> to <SEP> oscillate <SEP> around
 <tb> d'nll <SEP> axc # <SEP> <B> 130. </B> <SEP> When <SEP> this <SEP> mirror <SEP> oscillates, <SEP> the
 <tb> fornlc @ <SEP> 11'longreproduced <SEP> by <SEP> the <SEP> mirrors
 <tb> port (:. <SEP> by <SEP> 12-1. <SEP> 12-5 <SEP> and: <SEP> ID;

    <SEP>: have <SEP> rendered <SEP> visible, <SEP> either <SEP> in <SEP> looking <SEP> directly <SEP> on
 <tb> mirror <SEP> swivels <SEP> 129. <SEP> either <SEP> in <SEP> the <SEP> reflect on <SEP> a <SEP> screen <SEP> of <SEP> reception <SEP> parent half-trans <SEP> $ 1 1. <SEP> The <SEP> oscillations <SEP> of <SEP> mirror <SEP> are
 <tb> occ@l.ïATA <SEP> by <SEP> a <SEP> arm <SEP> who <SEP> is <SEP> held <SEP> by <SEP> a
 <tb> rcs:

  or1 <SEP> 13? <SEP> cn <SEP> contact <SEP> with <SEP> a <SEP> cam <SEP> <B> 133. </B>
 <tb> This <SEP> cam <SEP> is <SEP> pressed <SEP> by <SEP> a <SEP> engine <SEP> syli vhronc <SEP> (no <SEP> dcs.iné) <SEP> acc = supplemented <SEP> with <SEP> the tree <SEP> to
 <tb> cIa.lil1. <SEP> 13.1. <SEP> Lr # <SEP> nielleur <SEP> synchronous <SEP> receives <SEP> on <SEP> current. <SEP> of a <SEP> pciit <SEP> lilterilator <SEP> (no <SEP> drawn) <SEP> ac tionna <SEP> directly <SEP> by <SEP> the tree <SEP> 7l <SEP> bearing
 <tb> 1c .: <SEP> king] (-. <SEP> (the <SEP> way <SEP> that <SEP> the tree <SEP> to <SEP> cam <SEP> is.
 <tb> <B> z </B> <SEP> zi (#tioiiii ( <SEP> <B> - <SEP> î <SEP> to <SEP> li </B> <SEP> same <SEP> speed <SEP> that <SEP> the tree <SEP> <B> 71. </B>
 <tb>



  (the goose <SEP> results <SEP> that <SEP> the <SEP> movements Wave <SEP> <SEP> in rc <SEP>; ri? T <SEP> d <SEP> s <SEP> by <SEP> the <SEP> coils <SEP> test <SEP> -l <SEP> ï <SEP> and <SEP> i <SEP> G <SEP> appear. <SEP> like <SEP> being Stationary <SEP>, <SEP> garlic
 <tb> link <SEP> to move forward <SEP> on <SEP> on <SEP> field <SEP> of <SEP> vision.
 <tb>



  Enlightenment <SEP> (the <SEP> screen <SEP> 131 <SEP> is <SEP> inter ronipnc <SEP> he <SEP> vliaquc <SEP> revolution <SEP> in <SEP> intercepting
 <tb> the <SEP> light <SEP> (the <SEP> the <SEP> source <SEP> of <SEP> light <SEP> to <SEP> help
 <tb> cl'lin <SEP> shutter <SEP> 135. <SEP> During <SEP> this <SEP> period
 <tb> of darkness. <SEP> the <SEP> cam <SEP> acts <SEP> on <SEP> on <SEP> mirror <SEP> and <SEP> on
 <tb> t-; iinene <SEP> ù <SEP> his <SEP> position Initial <SEP>, <SEP> after <SEP> what <SEP> the.
 <tb> light <SEP> ('if <SEP> <B> (the </B> <SEP> new <SEP> allowed <SEP> for <SEP> 111111111111'r
 <tb> the e'Ierati.
 <tb>



  Effectively <SEP> this <SEP> is not <SEP> that a <SEP> stain <SEP> ln niineuse <SEP> who <SEP> c.t Thoughtful <SEP> <SEP> on <SEP> screen, <SEP> stupid
 <tb> @, r @ lce <SEP> to <SEP> the <SEP> rotation <SEP> fast <SEP> of <SEP> the tree <SEP> to <SEP> quail
 <tb> and <SEP> to <SEP> the <SEP> faculty <SEP> like <SEP> under <SEP> on <SEP> name <SEP> (the <SEP>., Per sistallce <SEP> <B> (the </B> <SEP> vision ". <SEP> the <SEP> stain <SEP> bright <SEP> appears <SEP> like <SEP> line Perfect <SEP> <SEP> more <SEP> on <SEP> less
 <tb> ondulc @ e. <SEP> <B> <I> This., </I> </B> <SEP> effects <SEP> are <SEP> good <SEP> known <SEP> and <SEP> described, <SEP> by <SEP> e - ,, eniplc <SEP> in <SEP> the. <SEP> publication <SEP> "III <B> email <SEP> Eleetrleill <SEP> 11ensurin- ' </B> <SEP> Instruments ",
 <tb> pn @ es <SEP> <B> 378 </B> <SEP> and. <SEP> 379.

    <SEP> published <SEP> in <SEP> 1918 <SEP> at <SEP> Table package <SEP> & <SEP> C'olnpan @ - <SEP> Ltcl .. <SEP> London.
EMI0015.0002
  
    The <SEP> three <SEP> circuits 2-wire <SEP>; <SEP> 124. <SEP> <B> 125 </B> <SEP> and
 <tb> 1? G <SEP> bearing <SEP> the <SEP> mirrors <SEP> oscillating <SEP> (no <SEP> re presented) <SEP> of <SEP> the oscillograph <SEP> are <SEP> connected
 <tb> respectively <SEP> to <SEP> circuits <SEP> of which <SEP> on <SEP> wants,
 <tb> or <SEP> good <SEP> observe, <SEP> on <SEP> good <SEP> register <SEP> the <SEP> shape
 wave <tb>. <SEP> For <SEP> of;

    <SEP> reasons <SEP> explained <SEP> below. <SEP> the oscillograph <SEP> mentioned <SEP> binds <SEP> will be, <SEP> used <SEP> due <SEP> for <SEP> the <SEP> goals <SEP> observation. <SEP> The
 <tb> circuit Oscillograph <SEP> <SEP> 124 <SEP> is <SEP> connected <SEP> directly <SEP> to Secondary <SEP> <SEP> 110 <SEP> of <SEP> transformer <SEP> who <SEP> receives <SEP> its <SEP> pulses <SEP> of <SEP> the <SEP> part <SEP> of <SEP> the
 <tb> coil <SEP> test <SEP> rotary <SEP> <B> 77. </B> <SEP> The <SEP> circuit Oscil lograph <SEP> <SEP> 125 <SEP> receives <SEP> its <SEP> pulses <SEP> of <SEP> shake up <SEP> 121 <SEP> of <SEP> transformer <SEP> who <SEP> is <SEP> in <SEP> con nexion <SEP> with <SEP> the <SEP> coil <SEP> test Stationary <SEP>
 <tb> <B> 76. </B> <SEP> The <SEP> circuit Oscillograph <SEP> <SEP> 12G <SEP> receives <SEP>

  his
 <tb> current <SEP> dune <SEP> source <SEP> of <SEP> current <SEP> alternative
 <tb> <B> 136 </B> <SEP> of a <SEP> frequency Constant <SEP> <SEP> defined. <SEP> by
 <tb> example <SEP> -10 <SEP> periods <SEP> by <SEP> second. <SEP> of <SEP> way
 <tb> that <SEP> the <SEP> indications <SEP> data <SEP> by <SEP> on <SEP> operation <SEP> of <SEP> this <SEP> member <SEP> of <SEP> the oscillograplie <SEP> ser vent <SEP> in <SEP> same <SEP> time <SEP> like <SEP> measure <SEP> normal
 <tb> from <SEP> time <SEP> for <SEP> the <SEP> waves <SEP> produced <SEP> blanks <SEP> on
 <tb> places <SEP> others <SEP> circuits <SEP> of <SEP> the oscillograph.
 <tb>



  The <SEP> electro-aima <SEP> beds <SEP> chi <SEP> second <SEP> oscillo; raphe <SEP> mentioned <SEP> are <SEP> designated <SEP> by <SEP> <B> 137 </B> <SEP> and
 <tb> are <SEP> excited <SEP> by <SEP> on <SEP> current <SEP> of <SEP> the <SEP> line <SEP> main <SEP> 1 \ _l3, <SEP> bringing <SEP> on <SEP> current <SEP> to <SEP> electromagnets <SEP> dcl <SEP> first <SEP> oscillograph. <SEP> The, <SEP> source
 <tb> -de <SEP> light <SEP> for <SEP> enlighten <SEP> the <SEP> mirrors <SEP> oscillating
 <tb> no <SEP> represented <SEP> is <SEP> a <SEP> lamp <SEP> to <SEP> arc <SEP> (lion <SEP> re presented) <SEP> cooperating <SEP> with <SEP> 1a <SEP> lens <SEP> 1-11 <SEP> and
 <tb> the <SEP> prisms <SEP> 14 ?.

    <SEP> The <SEP> spots <SEP> bright <SEP> coming from <SEP> of <SEP> three <SEP> mirrors <SEP> oscillating <SEP> of <SEP> this
 <tb> oscillograph <SEP> are Projected <SEP>, <SEP> unlike <SEP> to
 <tb> those <SEP> of <SEP> first <SEP> oscillograph, <SEP> directly,
 <tb> on <SEP> a <SEP> movie Photographic <SEP> <SEP> 143, <SEP> which one,
 <tb> of hile <SEP> way <SEP> blue <SEP> like. <SEP> is <SEP> 1171s <SEP> in <SEP> inotl vement <SEP> to <SEP> the moment <SEP> same <SEP> where <SEP> a <SEP> inlanc <SEP> must
 <tb> to be <SEP> done.

    <SEP> These <SEP> spots <SEP> lunlineuse. # <SEP> plot <SEP> by
 <tb> parcelzéquent <SEP> on <SEP> on <SEP> movie <SEP> a <SEP> shape <SEP> (the wave
 <tb> matching <SEP> to <SEP> that <SEP> of <SEP> currents <SEP> respec tives <SEP> sent <SEP> -to <SEP> through <SEP> the <SEP> members <SEP> oscillating
 <tb> from <SEP> the oscillonraplie.
 <tb>



  We <SEP> will notice <SEP> due <SEP> the <SEP> members <SEP> osvil lanis <SEP> of <SEP> two <SEP> ocillotgraplies <SEP> are <SEP> connected:
 <tb> in Parallel <SEP>, <SEP> of <SEP> way <SEP> to <SEP> receive <SEP> the <SEP> two
 <tb> <B> exaeienloni <SEP> him <SEP> current <SEP> (the </B> <SEP> same <SEP> character.

         
EMI0016.0001
  
    In <SEP> both <SEP> that <SEP> the <SEP> phenomena <SEP> of oscillations
 <tb> in <SEP> the <SEP> wheel <SEP> of <SEP> turbine <SEP> to <SEP> try <SEP> are <SEP> of
 <tb> character <SEP> transient, <SEP> the <SEP> presence <SEP> or <SEP> the absence <SEP> of <SEP> this. <SEP> phenomena <SEP> of oscillations <SEP> is
 <tb> observed <SEP> by <SEP> inspection <SEP> of <SEP> reflections <SEP> of
 <tb> mirror <SEP> oscillating <SEP> 129. <SEP> Thanks <SEP> to <SEP> his <SEP> connection
 <tb> to <SEP> same <SEP> circuit <SEP> electric.

    <SEP> the oscillograph
 <tb> with <SEP> on <SEP> movie Photographic <SEP> <SEP> 1-13 <SEP> receives <SEP> of
 <tb> vibrations <SEP> or <SEP> oscillations Corresponding <SEP>.
 <tb> II <SEP> is <SEP> obvious <SEP> due, <SEP> to <SEP> the exception <SEP> (read <SEP> case <SEP> where
 <tb> one <SEP> wants <SEP> raise <SEP> a <SEP> itna @, e. <SEP> on <SEP> movie <SEP> photo 143 <SEP> is <SEP> rendered <SEP> inoperative <SEP> eyelash <SEP> fishing <SEP> the <SEP> light <SEP> from <SEP> of <SEP> mirrors
 <tb> oscillating <SEP> (the <SEP> reach it. <SEP> Yes. <SEP> however, <SEP> the operator <SEP> remark. <SEP> clans <SEP> on <SEP> mirror <SEP> 129 <SEP> (the <SEP> the cillograph bone <SEP> used <SEP> for <SEP> observation, <SEP> the appearance <SEP> of a <SEP> phenomenon Oscillation <SEP> <SEP> eulier party <SEP> that he <SEP> is <SEP> desirable <SEP> (the enrei;

  record, <SEP> he
 <tb> can <SEP> give <SEP> he <SEP> the moment <SEP> wanted <SEP> order <SEP> to <SEP> sound
 <tb> assistant <SEP> who <SEP> done <SEP> then <SEP> on <SEP> required <SEP> to <SEP> the eillograplie-enrebistreur bone <SEP> for <SEP> perform <SEP> the ex position <SEP> chi <SEP> movie <SEP> 1-1: 3. <SEP> who <SEP> can <SEP> then <SEP> be
 <tb> (1 (#c <SEP> (, loppé <SEP> and <SEP> copied <SEP> of <SEP> the <SEP> way <SEP> tiuelle.
 <tb>



  We <SEP> a <SEP> mentioned <SEP> the electromagnet
 <tb> stationary <SEP> 91 <SEP>: wandering <SEP> to <SEP> put <SEP> the <SEP> wheel <SEP> to
 <tb> try <SEP> in <SEP> vibration. <SEP> In <SEP> the, <SEP> fig. <SEP> 16 <SEP>.: Have <SEP> indicated <SEP> on: <SEP> eirruits <SEP> of a <SEP>;

  magnifying glass <SEP> niotr # ur-generator <SEP> for <SEP> provide <SEP> of <SEP> current <SEP> electric <SEP> (the
 <tb> any <SEP> frequency <SEP> desired. <SEP> 144 <SEP> designates <SEP> the Turkish army <SEP> (Fun <SEP> nF-narator <SEP> to <SEP> current Alternative <SEP>.
 <tb> including <SEP> winding <SEP> of <SEP> field <SEP> 145 <SEP> is <SEP> powered <SEP> by <SEP> of <SEP> current <SEP> continuous <SEP> of <SEP> the <SEP> line
 main <tb> <SEP> 1? 3. <SEP> A <SEP> rheostat <SEP> l4 (i <SEP> serves <SEP> to <SEP> set
 <tb> the <SEP> field <SEP> (the <SEP> this <SEP> generator <SEP> to <SEP> current <SEP> native alter. <SEP> A <SEP> engine <SEP> activating, <SEP> this <SEP> generator
 <tb> is <SEP> represented <SEP> with <SEP> sound <SEP> induced <SEP> 147 <SEP>:

  sure <SEP> on
 <tb> same <SEP> tree <SEP> due <SEP> the alternator <SEP> and <SEP> with <SEP> a <SEP> eil bearing <SEP> (the <SEP> field <SEP> 1-18 <SEP> powered <SEP> from
 <tb> the. <SEP> line <SEP> main <SEP> 1? 3. <SEP> The <SEP> speed <SEP> of <SEP> group
 <tb> engine-alternator <SEP> can <SEP> be <SEP> varied, <SEP> clans <SEP> of
 <tb> limits <SEP> too <SEP> wide <SEP> due <SEP> clasiraea, <SEP> to <SEP> V <SEP> help
 <tb> from <SEP> rheostat:

    <SEP> appropriate <SEP> 1-19 <SEP> and <SEP> 150. <SEP> Reads
 <tb> tacllvmÈ # tre <SEP> or <SEP> all <SEP> other <SEP> instrument <SEP> appro
 <tb> prayed <SEP> for <SEP> nic # .: urer <SEP> the <SEP> speed <SEP> can <SEP> serve <SEP> to
 <tb> nwurer <SEP> the <SEP> ritc..ae <SEP> (reads <SEP> group <SEP> engine-generator linker <SEP> and <SEP> somebody <SEP> tacliyniètre <SEP> electric
 <tb> is <SEP> used. <SEP> relui-ri <SEP> small <SEP> be <SEP> gra (read @ <SEP> of <SEP> way
 <tb> to <SEP> indicate <SEP> the <SEP> fradnenile <SEP> (the <SEP> <B> He </B> <SEP> altvrnateu <SEP> r.

       
EMI0016.0002
  
    For <SEP> try <SEP> a <SEP> wheel <SEP> of <SEP> turbine, <SEP> he <SEP> is
 <tb> indicated <SEP> of <SEP> determine <SEP> first <SEP> the <SEP> period
 <tb> natural <SEP> of <SEP> vibration <SEP> of <SEP> the <SEP> wheel <SEP> to <SEP> rest.
 <tb> This <SEP> can <SEP> be <SEP> done, <SEP> by <SEP> example, <SEP> before
 <tb> that <SEP> the <SEP> wheel <SEP> either <SEP> placed <SEP> clans <SEP> the <SEP> machine <SEP> to
 <tb> try, <SEP> in <SEP> using <SEP> a <SEP> electromagnet <SEP> excited
 <tb> (the <SEP> way Appropriate <SEP> <SEP> and <SEP> placed <SEP> on <SEP> a <SEP> foundation <SEP> solid. <SEP> L <SEP> a <SEP> layout <SEP> can <SEP> be
 <tb> like <SEP> indicated <SEP> to <SEP> fib.

    <SEP> 8 <SEP> to <SEP> 11, <SEP> clans <SEP> which <SEP> the electromagnet <SEP> is <SEP> indicated <SEP> in <SEP> 38.
 <tb> He <SEP> is <SEP> assumed <SEP> due <SEP> the <SEP> wheel <SEP> itself <SEP> is
 <tb> outfit <SEP> clans <SEP> a <SEP> plan <SEP> horizontal <SEP> in <SEP> the <SEP> fixing
 <tb> to <SEP> through <SEP> the opening <SEP> -from <SEP> moveu <SEP> on <SEP> a <SEP> foil dation <SEP> solid, <SEP> and <SEP> due <SEP> the electromagnet <SEP> is <SEP> fixed
 <tb> also <SEP> to <SEP> help <SEP> of a <SEP> caliper <SEP> or <SEP> others
 <tb> means <SEP> on <SEP> the <SEP> same <SEP> foundation. <SEP> A <SEP> group
 <tb> engine-alternator, <SEP> like <SEP> indicated <SEP> in <SEP> fig.

    <SEP> 16.
 <tb> can <SEP> serve <SEP> for <SEP> feed <SEP> the electromagnet
 <tb> from <SEP> heavy <SEP> alternative <SEP> and <SEP> the <SEP> frequency <SEP> of <SEP> this
 <tb> current <SEP> can <SEP> be <SEP> decayed <SEP> in <SEP> cariant <SEP> ii <SEP> your will <SEP> the <SEP> speed <SEP> of <SEP> rrroup <SEP> niotor-alternator. <SEP> Dan:

    <SEP> some <SEP> case, <SEP> he <SEP> can <SEP> be <SEP> desirable
 <tb> from <SEP> determine <SEP> the <SEP> or <SEP> the <SEP> frequencies Natural <SEP>
 <tb> from <SEP> the <SEP> wheel, <SEP> after <SEP> due <SEP> this one <SEP> a <SEP> summer <SEP> climb
 <tb> on <SEP> sound <SEP> tree, <SEP> because <SEP> due <SEP> the <SEP> rigidity <SEP> slightly <SEP> increased, <SEP> due <SEP> to <SEP> the <SEP> presence <SEP> <B> (the </B> <SEP> the tree,
 <tb> auo-niente <SEP> the <SEP> frequency <SEP> of a <SEP> bind <SEP> degree.
 <tb> The effort Pulsating <SEP> <SEP> product <SEP> by <SEP> excitement
 <tb> from <SEP> the electromagnet <SEP> to <SEP> the. <SEP> continued <SEP> says <SEP> current
 alternative <tb> <SEP> puts <SEP> on <SEP> disk <SEP> <B> (the </B> <SEP> turbine <SEP> eyelash <SEP> vibra tion Corresponding <SEP>.

    <SEP> He <SEP> must <SEP> notice
 <tb> that in <SEP> both <SEP> due <SEP> the electromagnet <SEP> exercises <SEP> a
 <tb> effort <SEP> for <SEP> each <SEP> half period <SEP> of <SEP> current
 alternative <tb>, <SEP> attraction Pulsating <SEP> <SEP> exercised <SEP> on
 <tb> the <SEP> wheel <SEP> is <SEP> digitally <SEP> on <SEP> double <SEP> of <SEP> the
 <tb> frequency <SEP> of <SEP> current. Alternative <SEP>.
 <tb>



  To <SEP> of <SEP> determine <SEP> on <SEP> number <SEP> of <SEP> nmuds
 <tb> products. <SEP> the <SEP> areas <SEP> (the <SEP> the <SEP> wheel, <SEP> to <SEP> inside <SEP> <B> tick </B>
 <tb> the <SEP> periphery, <SEP> close <SEP> of <SEP> vanes, <SEP> can <SEP> be
 <tb> fulfilled <SEP> of water, <SEP> the <SEP> vibration <SEP> having. <SEP> then <SEP> for
 <tb> effect <SEP> (the <SEP> provoke <SEP> <c <SEP> the <SEP> surface <SEP> (the <SEP> water <SEP> <B> (the </B>
 <tb> small <SEP> ripples <SEP> corresponding <SEP> to <SEP> by lies <SEP> (the <SEP> the <SEP> wheel <SEP> vile <SEP> vibration, <SEP> stupid <SEP> <B> (the </B> <SEP> leave
 <tb> the. <SEP> surface <SEP> (the <SEP> water <SEP> smooth <SEP> and <SEP> without <SEP> trouble <SEP> to
 <tb> places <SEP> where <SEP> the <SEP> vibrations <SEP> do <SEP> se <SEP> produce
 <tb> not.

    <SEP> This <SEP> returns <SEP> the <SEP> figures <SEP> ilodals <SEP> (the <SEP> continued
 <tb> laughable, <SEP> of <SEP> way <SEP> due <SEP> on <SEP> number <SEP> of <SEP> ncnuds
 <tb> can. <SEP> college, ileinvnt <SEP> î # be <SEP> (Ic4ermina. <SEP> Alirè, <SEP> As the wheel has been placed in the wheel testing machine, the fr (, permanent license corresponding to each particular number of nodes can easily be checked by observation or recording using the ascillograplie.



  The end. 17 to 21 are photographic oscilloscope reproductions of a wheel tested in the testing machine. In the end. 17. sine wave 151 is the time wave corresponding to the alternating current of the main power line <B> 136 </B> (fib. 16). Curve 152 is the diagram recorded by stationary test coil 76.

   The vibration of the wheel revealed by this curve 152 is caused by the action of the alternating current electromagnet 91 (fis. 12 and 1G). When the. frequency of the current of this electromagnet rises to a value corresponding to one of the nodal frequencies of the wheel, the result is a relatively large vibration of the wheel volume curcnistré on: the wire in 152.

         In general. It is sufficient to observe the formation of vibrations of maximum amplitude with the aid of the indicator oscillograph and (the determine their frequency from the speed of the motor-alternator.



  If the wheel ic to try is now set and rotating, the current of the alternating current electromagnet 91 before has been interrupted, the. test coil 76 gives indications in oscillographs, even if a critical speed, at which a phenomenon <the oscilla lion could occur is not reached. Indications of this kind are represented by the recording of the film reproduced at the end. 18.

   Here, as above. <B> 151 </B> is the time curve. The irregular line 153 is the diagram obtained from the test coil <B> 76. </B> This curve represents a diagram of <B> the </B> wheel when it turns rigidly and is completely free from the phenomena of oscillation. It will be noted that different characteristic pas- sacres -in the line are repeated at regular intervals. So for example. the points 154 are repeated at regularly spaced intervals.

   The distance between two points 1 to 4 represents the time of one revolution of the wheel. By comparing it with the time curve 151, which in this case was that of an alternating current <B> (the </B> -10 periods, the rotational speed of the wheel can be exactly determined from the film image and can be controlled with the speed of the turbine or other machine operating 1a. wheel to try. Lime 153, with. its irregularities;

      repeating regularly. can be considered as the autograph of the wheel, because it is different for each zone tested.



  The diagram <B> 155 </B> on the oscillobrapliique film, in fib. 18, is that of the rotating coil <B> 77. </B> We will notice. that this diagram shows many fluctuations of very small amplitude.

   They are so small that they can be overlooked and indicate that at this time. he hadn't <B> (the </B> oscillation phenomena in the wheel.



  After an increase in the speed of rotation tle the wheel. a point was finally reached where phenomena of strong oscillations developed. This is clearly represented in the. rope diagram in fig. 19. As above. the curve (the time is shown in 151 and the diagram of the.

         stationary cc-sai coil in <B> 156. </B> 157. is the diagram of the rotating test coil. It will be noted that the diagram of the rotating test coil now has very marked waves, while the diagram 151 of the stationary coil is substantially unchanged. This indicates the presence of considerable traveling waves in the turbine wheel.

   As these moving waves pass through the rotating coil <B> 77, </B> the. adjacent portion of the wheel oscillates back and forth to produce the oscillogram <B> 157. </B> Note that during each revolution, as indicated by the distance between the points 154 in fiâ. 19, three uncle peaks occur on either side of the zero line in the diagram <B> 157 </B> of the rotating spool.

   Then he v a. three uncle crests on each side of the wheel. this diagram indicates the presence of a six-node oscillation phenomenon. In addition, the fact that the stationary coil provides in the fi. 19 the same diagram 154 as in FIG. 18, indicates that the oscillations in the wheel had no influence on the stationary coil. Consequently, it follows that the oscillations were stationary in space and that the wheel tested had turned at a critical speed corresponding to a phenomenon of bone cillation of six knots.



  The wheel was then left to turn for a short time at this speed, after which the bone cillograph revealed certain modifications in the phenomena of oscillations as shown in fig. 20. It will be noted that the oscillation phenomena represented in diagram 158 of the rotating coil have become much more marked, and, moreover, that diagram 159 of the stationary coil has lost its primitive character and shows a series. of waves which, upon examination, are found to be exactly twice as numerous as those appearing in dia gram 158 of the rotating coil. This dual frequency oscillation 159 represents an oscillation - propagating in the front wheel.

   The fact that the frequency of curve 159 is exactly twice as great as the frequency of curve 158, confirms the fact that we are dealing here with a phenomenon of critical speed, in which the oscillation propagating in the rear wheel is stationary in space and has a forward directed oscillation of smaller amplitude superimposed on the first. We can designate such a critical speed as an important critical speed because it occurs most often and because the magnitude of the oscillation phenomenon is much more pronounced than in the cases of critical speeds due to the oscillations which occur. propagate in the. wheel at speeds which are not (the nature of causing the bones to become stationary in space.

    



  The diagram (Fig. 21 shows what happens when the speed of the turbine wheel is increased slightly above that corresponding to the diagram in fig. 20. Note that the diagram 160 of the fixed coil and The rotating coil diagram 161 practically took over the conditions shown in Fig. 18, in which the wheel speed was slightly lower than the critical speed, instead of being slightly higher than the critical one as in Fig. 21.

   \ Tests carried out with wheels in the machine to be tested have demonstrated the extraordinary fact that oscillation phenomena, taking place in radial nodes, do not follow the natural period of vibration which the wheel exhibits at rest or being arrested. It is a fact that the natural vibration periods of the wheel increase when the wheel is rotated.

   This can easily be shown by putting the wheel into nodal vibrations corresponding to one of the different numbers of nodes, using the alternating current electromagnet 91 (wire 12) with the wheel at rest and keeping the wheel at rest. then putting the wheel in rotation, while it is in violent nodal vibration. When the speed of the wheel has increased enough, the vibration will turn off.

   By then increasing the frequency of the magnet excitation by a sufficient amount, the wheel can again be moved sideways to give nodal oscillations of the same number of nodes. Further, it has been found that the same nodal oscillatory motion can be produced not only by increasing the frequency of the excitation of the electromagnet by a given amount, but also by reducing this frequency. In other words, two frequency values of the excitation electromagnet serve to produce (similar resonance conditions in the wheel.

   This phenomenon demonstrates that the disturbances of rupture of the turbine wheels are in truth not due, as it has been claimed until now by seeking to give an explanation. to., wobbles. ments "or vibrations of the wheels, but at the oscillations in the wheel itself, propagate in the wheel in one or the other of two directions or in both directions at the same time.

   If, therefore, for a given speed of rotation of the wheel, a certain pulse frequency, lower than that which would cause the wheel to vibrate in the idle state, were applied to the wheel, an oscillation propagating in the rear wheel would be induced in it, While, if a higher frequency were applied, there would be induced an oscillation traveling the wheel forward at the same speed as the oscillation which traverses it backwards. .



  These relationships are shown in the diagram of fig. 22. The horizontal coordinates represent the speeds of rotation of the turbine wheel, and the vertical coordinates represent the frequencies of the pulses (read <i the alternating current electromagnet 91, and also of the.

   wheel itself. In the particular example shown, the turbine wheel has a frequency at rest (the oscillation corresponding to a vibration at four knots, of 60 Periods per second, as indicated in point 162. When the wheel is rotated, the frequency of the four-north oscillation phenomenon no longer remains stationary, but is found to increase along the line designated 163. This increase in frequency can be directly determined from the diameters of the rotating coil.

   In fig. 20, the upper curve 158 represents the wave peaks passing through the rotating coil, and thus, comparing the number of wave peaks with the. time curve 151, the frequency can be directly determined and set.



  As a test following this determination of the running frequency, the wheel can be vibrated by means of, for example, the alternating current electromagnet 91, with such upper and lower frequencies as to correspond, for each as speed of a series of different speeds, at points on curves 164 and 165. The curves shown in fig. 22 correspond to curves established according to actual data recorded in a wheel testing machine.

   Note that points on the curve <B> 165 </B> are distant above the walking frequency curve <B> 163 </B> quantities exactly equal to the distances between the corresponding points on curve 164 above the running frequency curve <B> 163. </B>



  The lower frequency applied to the alternating current electromagnet 91, which is necessary to cause the development of this phenomenon of nodal oscillation in a turbine wheel, decreases more and more, as the speed of the. wheel increases. This can be seen by examining curve 164 (fig. 22). Eventually a point will be reached, for which the curve passes through the zero frequency line. This then means that the force that must be applied to the wheel to cause the development of oscillation phenomena is a force of zero frequency, that is to say a force acting in one direction.

   One might therefore expect that if a wheel is running at a critical speed, but has no oscillation phenomena, bone cillation phenomena would develop by pushing the wheel sideways. This has in fact been done, in some cases, by subjecting the periphery of a rotating wheel with flat surfaces to a deflection using a piece of wood, the constant tensile force of an electric -dc magnet, a jet of fear or similar means. By these means, a phenomenon of stationary oscillation has been developed. .



  When a wheel at rest is set in vibration, it can be assumed that there are nodal wave trains in the wheel moving at equal speeds, but in opposite directions. When the wheel is rotated, the velocity, in space, of one key wave train is increased and that of the other is reduced equally.

    But by the fact <B> of </B> the rotation of the. .wheel, the effect of the centrifugal force comes into play in that there is an increase in the natural frequency of the wheel, because the natural inertia of the wheel, which resists deformation of the wheel , is supplemented by the centrifugal force which acts in a similar way, but increases with speed. What we can call the running frequency of nodal phenomena is therefore always greater than the fixed frequency or the frequency of the wheel at rest.



  For a given speed of the wheel, the frequency with which the wave peaks due to the wave train propagating backwards, pass through a given point in space, is increased by an amount equal to
EMI0020.0004
   NB (the representing the number of knots and Ng the walking speed) and the frequency due to the wave train propagating forward is increased in the same way. But  . Frequency change should not be derived from the frequency corresponding to the rest frequency, but from the running frequency which is different for each rotational speed.

   If we now apply deflection forces to the wheel with the same frequency with which the peaks of waves, either of the wave train propagating forward or of the wave train propagating backwards, pass through a fixed point in space, it is obvious that a resonance condition will be produced. This frequency is equal to the walking frequency plus or minus
EMI0020.0009
   Ne These relationships, confirmed by tests, are represented by the diagram in fig. '' 22, in which the vertical distances between the curves 163 indicate the running frequency and the curves 161 and 165 respectively give the lower and upper applied frequencies. corresponding, for each speed of rotation, to the speed in space of the wave peaks in the wheel.

   These differences are always exactly equal and are shown in fig. 22 as being equal to
EMI0020.0012
       A ",, (where ri is, as above, the number of radial nodes and N. the speed of rotation) and correspond to the frequencies of the oscillations in the wheel. The ordinates Al and H of curves 164 and 165 represent, on the other hand, the frequencies of the waves in space. It is obvious that by increasing the speed of the wheel, the oscillations moving forward will advance more rapidly in space and the oscillations will grow faster. paging back more slowly.

   The backward propagating oscillation will therefore eventually reach a point where it becomes stationary in space. This is represented by the descending strand of curve 165, the extension of which would cross the horizontal axis at the speed corresponding to this point. This is a major critical speed already mentioned.



  * The running frequency 163 then becomes equal
EMI0020.0020
   This can be expressed by
EMI0020.0021
       11T "f .. being equal to the running frequency or nodal frequency at bare speed NB of the wheel. If we determine experimentally in the manner described, the running frequency for each given number of nodes, we find that the ratio between the frequency (the market f = and the rest frequency f, can be expressed by the following equation:
EMI0020.0028
    B being a coefficient depending on the physical characteristics of the wheel, different for different wheels.

   Fig. 23 graphically gives a number of values for the coefficient B varying between 1.49 and 2.24.



  From the two given equations, it easily follows that the critical speed for the corresponding number of nodes is expressed by the relation:
EMI0020.0032
    where N, represents, as above, the speed of the machines in revolutions per second, 7i the number of radial nodes, B a coefficient usually having an approximate numerical value of 2, and fe: the frequency (the rest or the frequency of the vibrating wheel.



       When, therefore, any one of a number of wheels of equal dimensions has been tested in the machine to test the wheels so as to determine the value of the coefficient B i, the critical speeds of the other wheels may be determined between very small error limits, by calculating them according to the nodal frequencies of rest of the wheel obtained only by putting the wheel at rest in vibration, either by an electromagnet as already described, or by <other means.

      The diagram in fig. 22 shows only the data concerning oscillation phenomena of a given nodal condition. It is however necessary for the construction of the turbine wheels which must run safely with a given running speed, to determine corresponding data for nodal phenomena of different number of nodes which can produce dangerous running conditions.

   The fi-. 23 includes a series of diagrams, such as fi ;. 22, corresponding to nodal wave phenomena of different names of mouds. Thus, the three lines emanating from point 166 represent phenomena of four-node oscillations; the lines emanating from point 167 represent phenomena of oscillations at six nmuds;

       the lines emanating from point 168 corresponding to phenomena of oscillations at eight nodes, while the lines starting from point 169 correspond to phenomena of oscillations at said nodes. On the diagram (fig. 23 are shown the values of constant B for the different nodal conditions corresponding to the particular wheel whose characteristics are shown in this figure. The thick line 170 should indicate the walking speed. of the wheel (the turbine.

   The value of the coefficient B of the particular wheel tested is indicated in each of the diagrams of bone cillation phenomena in fig. 23 for each number of nodes.



  Note that lines 171, 172 and 173 corresponding to the lower applied frequency 31, line 164 in fig. 22, intersect the horizontal coordinate axis at points representing speeds close to walking speed, while extending line 174 would intersect the horizontal axis at a point further from the walking speed point.

   This diagram shows that the wheel in question would develop stationary oscillations phenomena corresponding to six, eight and ten knots at speeds slightly lower than the running speed, but would not develop corresponding oscillations phenomena. at four knots, except for a speed considerably above ground speed.



  When these critical speeds indicated by the points of intersection with the zero line correspond to the frequency of rotation of the wheel, as has already been explained, any stationary force applied will induce oscillations in the wheel. It should be noted in passing that, if during the operation of the wheel itself, there is any force acting periodically on the wheel, such a force, if its period or frequency is of suitable value, can have the same effect as the The alternating current electromagnet 91 a by inducing oscillation phenomena in the wheel.

   If, for example, the wheel, or its shaft, or other rotating parts are unbalanced so as to produce periodic pulses of the same frequency as the speed of rotation of the wheel, oscillation phenomena may develop each time. once these pulses coincide with the frequencies represented by the applied lower frequency curve JI, such as curve 164 in the diagram of FIG. 22, or curves 171 to 174 of fia. 23. Line 175 in fig. 23 is a straight line drawn through (the ordinates which correspond to frequencies numerically equal to the rotational speeds.

   If there is, therefore, a pulsation for each revolution of the wheel, due to an imbalance or similar cause, it can be expected that: oscillation phenomena will develop at the points where this line crosses lines 171 through 174. However, it has been found that such difficulties occur very rarely, are of small value and can be overlooked. We can, therefore, designate the speeds at which these phenomena can occur as minor critical speeds because they are of relatively small importance and occur infrequently.

   The critical speeds at ten knots and those of even higher order have been found to be of little importance. Two-knot oscillations cannot remain stationary in space and are also insignificant.



  To ensure the safe operation of an elastic fluid turbine, it is of course essential that all rotor wheels without exception be of such construction that they do not exhibit critical speeds in dangerous proximity to the operating speed of the turbine. rotor. The meaning of this condition can perhaps be made more understandable by establishing the critical speeds of the rotor wheels in diagram form.

    Figs. 24 and 25 show such graphs or diagrams for the case of two twenty-two-stage steam turbines not incorporating the present invention. In these diagrams, the ordinates represent revolutions per minute of the turbine rotor wheel; the horizontal lines represent different wheels of the corresponding rotor, according to the sequence number of the stage. Thus horizontal line 10 represents the wheel of the heavy floor, the next one, although not numbered, represents the wheel of the moon floor, line 12 the wheel of the 121st Floor etc.

   For each wheel is noted, as data was obtained from it, a critical speed corresponding to four knots, another to six knots and another to eight knots. These critical speeds are indicated in the diagram, respectively by circles, squares and triangles.

   For all the wheels, the critical speed points corresponding to a given number of nodes are connected by a line so that for each number of nodes, the relationships of the critical speeds in the different turbine wheels can be observed more easily.

   Thus in fig. 24, a dotted line marked "six knots" passes through all six knot critical speed points. Similarly, other lines pass through the critical speed points corresponding to four knots and eight knots.



   <B> El </B> n fig. The critical speed points corresponding to different nodes are connected together in a similar fashion.



  It will be noted that in this case, as well as the case shown in FIG. 24, there seems to be no other definite relation between the critical speeds of successive turbine wheels than a general tendency of those of the wheels which correspond to stages of lower rank and which are therefore of larger diameter. small, to have their critical points at higher rotational speeds than the turbine key wheels of higher stages which are therefore of larger diameter.



  It will be noted that in the two turbines whose critical speeds are represented in the fia-. 24 and 25, there is in one of the turbines - the critical speeds of certain wheels approaching dangerously close to the operating speed, while in the other, the speeds of the corresponding wheels remain far apart with sufficient distance. security thereof.

   Thus, in fig. 2.1, the wheels of the 151nc and 17th stage all have critical speeds corresponding to six and eight knots, manifesting themselves close to the speed (the service, while in the turbine shown in figure 25, the critical speeds of the wheels although they are still very close to the operating speed, are however still far from it at least (the 10, ô.

       The critical four-knot speeds of the 20nie, 21mc and 22nd stage, however, fall in both diagrams to correspond very closely to the service speed.

   These diagrams serve to indicate not only the danger, but the practical certainty that there will be shown somewhere in the succession of the impellers of the turbine rotor one or more critical speeds in dangerous proximity to the operating speed and, for example, therefore, liable to give rise to accidents sooner or later in the existence of the turbine, if the dangerous wheels are not modified or, as we can say, "tuned".



  If the wheels of a low speed turbine rotor have been constructed and predetermined in accordance with the principles described above, the critical speed diagram, for all stages of the rotor, will reveal the complete absence of critical speeds in the immediate vicinity. diate of the service speed. Similar diagrams are shown in fig. 26 and 27; they are easily understood and represent machines with particularly favorable oscillation phenomena. It will be noted that, in both cases, there is no critical speed approaching more than 15% of the operating speed.

   However, it will be noted that in FIG. 26, the critical speeds in the wheels of the 16th and 17th stage, corresponding to six and eight nodes, are lower than the operating speed, while the case of the other turbine, whose critical speeds are shown in wire. 7, all critical speeds are above the service speed.

   The latter situation of critical speeds, above the operating speed, is naturally preferable if it can be achieved. The determination of the safety limits which should exist between the normal operating speed of the rotor, on the one hand, and the speeds at which dangerous oscillation phenomena are developed, on the other hand, involves a series of of considerations. First and foremost, there is a certain degree of resonance in which critical speeds can be developed.

    This means that oscillation phenomena do not occur with mathematically precise exactitude at a particular speed only, but can also occur at speeds slightly lower or higher than a speed given as corresponding to the condition of. maximum resonance. This margin above and below is referred to herein as "resonance latitude". Experience has shown that in the case of steam turbine wheels developing oscillation phenomena, this resonance latitude rises to about 2% above and 2% below the critical speed.



  Another factor that will be taken into account when determining the safety limits between the operating speed and the critical speeds is. determination -of the numerical coefficient B. This above-mentioned coefficient B is used to determine the magnitude of the nodal running frequency -of the turbine wheel, if the rest frequency is known. This coefficient varies according to the shape and construction of each particular turbine wheel and is determined, as already explained, by the actual testing of the wheel in the wheel testing machine (fig. 12).

   It is estimated that the errors which can occur by applying these coefficients or factors to equal wheels which have not passed the test machine, but which have been put into vibration for <B> de- </B> finish. their rest frequencies cannot exceed 5% a in the case of phenomena of nodal oscillations at six and eight knots. Slight changes in the natural frequency, due to temperature changes, are included in this 5% tolerance.



  Another consideration which should be taken into account is the fact that a turbo-alternator, when in hopscotch under practical conditions, is capable of being activated, in order to regulate the load. machine electric. if it runs together with other machines and for other possible reasons, no longer exactly at its prescribed speed, but at a speed which may be 3 ô greater or an equal amount less.



  By adding the mentioned percentage factors, namely the factors 2 -f- 5 -i- 3%, we obtain the number 10 which gives the lower safety limit, which is especially applicable to phenomena of oscillations at six and eight.

       knots. It has been found that in the case (the phenomenon of four-node oscillations, a greater error in the determination of the critical speed can occur by the use of the factor B, and it has been determined that this error can occur. increase to about 5 ô more than 5% in the case of six and eight knot oscillation phenomena. Therefore, the safety limit for the case of four knot oscillation phenomena is set to 15. # b.



  In the practical realization of the present invention, each wheel of a given turbine rotor must be predetermined and adjusted so as not to have critical speed points between the above-mentioned safety limits. This predetermination or adjustment may be based on the data obtained by rotating the wheel in a wheel test machine, as described above, or it may be performed based on natural frequency dependent calculations. of the wheel at rest, in cases where this wheel is so similar to other wheels already tested in the testing machine that the coefficient B can be used with a sufficient degree of accuracy.



       When proportioning or tuning a wheel, in order to obtain the desired relations between the critical nodal speeds of the wheel and the normal service speed, it is necessary that the relations between the rigidity of the parts of the wheel and the mass of the parts of the impeller are established so as to give the impeller the desired natural frequency of vibration. In general, it can be stipulated that in a vibrating system, such as a turbine disk, the frequencies of vibration increase with the stiffness of the wheel and decrease with an increase in the mass of the wheel.

   This can be expressed by the formula:
EMI0024.0016
    where r means stiffness and JI the mass of the wheel.



  It follows from this formula that the greater the rigidity of a wheel, and the smaller the mass, the higher the frequencies of vibration of the wheel will be.



  When designing a wheel or when proportioning or "tuning" an already - built wheel, the relationship thus expressed between the stiffness and mass of the wheel must be carefully observed in order to ensure the desired results. .



       Since nodal frequencies of different numbers of nodes corresponding to flexing actions extending into the body <B> (the </B> the wheel towards the center of it to a greater or lesser degree which depends on the number of nodes, one can expect that changes in the relations between stiffness and mass will influence the differences. rentes frequency values corresponding to the different numbers of - nodes. So,

    as can be seen with reference to fig. 8 to 11, the greater the number of nodes, the greater the distance inward to the center over which disturbances due to nodal deflection of the wheel are exerted. There should therefore be an appropriate coordination between the stiffness and the mass of the different portions of the wheel to obtain a wheel free from dangerous critical nodal speeds.



       Whenever there is a reason (the assumption that an existing wheel may have a critical node speed in the vicinity of the service speed, the wheel should first be vibrated before being mounted on the wheel. shaft and the critical nodal speeds thus determined as determined. To observe the nodal areas during the vibration of the wheel, it is advantageous to open the wheel flange with a thin layer of water. nodal vibration, the water surface will exhibit wavy or ridged areas in accordance with the nodal vibration areas.

   If any of the critical speeds then appear to be near the dangerous limit of the four, six and eight knot oscillation phenomena, the wheel must be mounted on the shaft on which it must walk in the turbine, and again be put into vibration in order to determine the critical speeds modified by the mounting of the impeller on the shaft. Usually the wheels have slightly higher critical speeds when mounted on the shaft than when tested when removed from the shaft.

   This difference can be estimated from previous tests of similar wheels, or it can be determined, as indicated; by an actual test of the wheel itself, when it is on the shaft. If the nodal speeds of the wheel mounted on the shaft are still within dangerous limits, the wheel will be. removed from the tree and synchronized by modifying its proportions so as to. change their frequency characteristics.



  The tuning or reprocessing of the wheel can be done in different ways. Thus metal can be removed in certain places, depending on the knot frequency to be changed, or the blades can be removed and remanufactured or replaced by <B> vanes </B> heavier.

   In order to ensure the desired ratio between the rigidity of the wheel and its mass, it is usually feasible, in the case of a wheel already built, to effect its proportioning by removing only material. because, for mechanical reasons, it is hardly possible to add material uniformly, except in the case of replacing the blades with heavier blades. As an example, one can assume the case of a 22nd stage impeller with vanes with a length of 28 inches and a disk diameter of 2.25 m.

    in which we found, after having it vibrated and calculated as described above, the existence of a critical speed four knots approximately 8% above the operating speed, and critical speeds corresponding to six and eight na: uds outside the 10% lower limit for these critical speeds. In this case, it is then necessary to raise the frequency from four nodes to at least 15% above the operating speed. This can be achieved by appropriately reducing the weight of the blades.

   This can be done by first temporarily attaching weights of known size to the tire of the wheel, so as to approximately determine the effect of the addition of weight on the frequency of the wheel. So, for example, different numbers of bolts can be fastened transversely on the edge of the sheath to provide the additional weight. The effect, approximate of different weights being thus obtained, the blades are then withdrawn and the known quantity of material is removed from the backs of the blades, thus achieving what are called conical blades.

   If the weight to be removed is very large, indeed too large to allow this adjustment, we will use another wheel, heavier, in order to have the frequency at four. knots at least 15% above operating speed.



  The removal of weight from outer or convex portions of the blades is shown, by way of example, in Figs. 28, 29 and 30. FIG. 28 is a partial section of an impeller along a plane passing between two blades. The normal contour line of a vane is shown in solid lines in fig. 29 at 17 G and 177. while the portion of material to be removed is indicated by the space limited by the dotted line 178.



  Fig. 30 is a section of the vane by the line x-x and indicates in solid lines <B> 179 </B> the primitive section of the vane and in dotted lines 180 the limits up to which the vane material has been removed to reduce the weight.

   Removing material from the vanes of an impeller reduces mass without ordinarily reducing the stiffness of the impeller too much, and results in an increase in the frequency of vibrations to four, five and eight knots and above and, therefore, critical nodal speeds ---- corresponding. As already explained, the critical speeds taken into consideration during these operations are calculated using the rest frequencies obtained by the vibration tests and the coefficient B called the running coefficient derived from the tests of similar wheels in the machine to be tested. the. wheels.



  As another example, consider a wheel with vanes' length of 30 cm and with a disc diameter of 1.8 m and assume that vibration tests have shown the existence of a critical speed at about six knots. 3% above service speed, a critical speed at eight knots about 4% below service speed, and a critical speed at four knots about 25 ° above speed of ' service.



  In this case, the critical speeds at six knots and at eight knots can be lowered by removing material from appropriate points on the wheel, but care should be taken to ensure that this is done so that the critical speed at four knots is not at the same time lowered proportionally so as to come within the dangerous limit of 15 / a;

    this assumes that the critical speed at six knots is brought to a point at least 10 10 below the operating speed, the critical speed at eight knots reduced from 4 below to 10 / a below the operating speed. running speed, and all this without lowering the critical speed at four knots by more than 10%: In such cases, great care must be taken to cut the wheel at the places which will most influence the critical speed nodal -that we want to modify.

   Thus, -in a wheel like the one considered, therefore a wheel with vanes 30 cm long, (modifications to the wheel flange near the edge or circumference have the greatest effect on the frequency of eight knots , while alterations in the area of the wheel six to eight inches closer to the center have the greatest effect on the six-node frequency. In an area still closer to the center of the wheel and away from the center of the wheel. from the center of 1/4 or 1/3 of the radius,

   changes by removing material from the flange have the greatest effect on the four-node frequency.



  For setting the frequency to six -. knots, the wheel is then placed on the lathe and is lightly worked in, an area extending from the edge of 15 to 20 cm towards the interior of the flange. The wheel is then lifted from the turn and again subjected to a vibration test, and the new frequency is determined in the same way as before. These operations will be repeated until the desired frequency is obtained. Then the wheel is placed on its own shaft and again vibrated to confirm the results obtained.



  In the case of a critical speed at eight. knots, the operation is the same, except that the twisting of the wheel on the lathe will be done closer to the edge of the wheel and may even extend to the edge itself. Here under edge of the wheel is meant the outer portion of the solid flange to which the blades are attached.



  In some cases where the removal of material does not produce a sufficient decrease in the natural frequency of the impeller, it will be necessary to replace the impeller blades with other heavier blades.



  Each modification of the wheel should of course be followed by a careful retesting in accordance with the above-mentioned method, in order to establish and confirm the results obtained by such modifications.



  In fic. 31 which represents a partial sectioci of a turbine wheel, the solid lines 181 and 182 indicate the region where metal has been removed from the outer part (read flange (the impeller. When removing (read metal from this region) , this considerably influences the frequencies corresponding to six and eight knots, but has little effect on the frequencies corresponding to four knots.



  In order to be sure that a frequency at four n (rucls is sufficiently high, for the case of study of new wheels, it is advantageously based on the fact that the frequency at four nodes is the most influenced by a modification of the stiffness of the large portion of the flange shown in Fig. 32, ie 183 and 184, the modification of the stiffness at these locations having more effect on the four-node frequency than the modification of the mass.



  The following table will serve to show how the successive removal of metal from a particular wheel, in different regions, influences the nodal frequencies:. Cut from the edge of the wheel as indicated by the dotted lib ies 185 and 186.

   Referring to the column (the nodal frequencies, one will notice. (Read this modification of the edge of the wheel changed the frequency at four nodes from 45.3 to 47.3 the frequency at six nodes from 63.2 to ti2, 7 and the eight knot frequency of 81.7 in 80.3 The third horizontal row of the above table shows the results of the removal of material from the wheel flange.

   As a result of this machining of the flange, dimension A near the edge of the wheel has been reduced by 0.32 cm, while dimension B near the hub of the wheel has been reduced by 0.15 cm, all other dimensions having remained the same. The contour line of the material thus lifted is shown in fig. 23 by the lines
EMI0027.0022
  
    Dimensions <SEP> Frequencies <SEP> nodals
 <tb> <U> B <SEP> I <SEP> C <SEP> I <SEP> D </U> <SEP> II <SEP> 2 <SEP> I <SEP> I <SEP> <U> 6 <SEP> I <SEP> 8 </U> <SEP> I <SEP> <B> 10 </B>
 <tb> 3.2 <SEP> cm <SEP> 4.9 <SEP> cm <SEP> 5.1 <SEP> cm <SEP> 6.75 <SEP> cm <SEP> 33.5 <SEP> 45.3 <SEP> 63.2 <SEP> 81.7 <SEP> 99.3
 <tb> 3.2 <SEP> " <SEP> 4.9 <SEP> " <SEP> 5.1 <SEP> " <SEP> 6.03 <SEP> " <SEP> 37.7 <SEP> 47.3 <SEP> 62.7 <SEP> 80.3 <SEP> 97.8
 <tb> 2,

  88 <SEP> " <SEP> 4.75 <SEP> " <SEP> 5.1 <SEP> " <SEP> 6.03 <SEP> " <SEP> 36 <SEP> 45.7 <SEP> 60.3 <SEP> 78 <SEP> 95.2
 <tb> 2.56 <SEP> " <SEP> 4.75 <SEP>., <SEP> 5.1 <SEP> " <SEP> 6.03 <SEP> " <SEP> 33.3 <SEP> 42.3 <SEP> 58 <SEP> 75.3 <SEP> 92.3 In this table, the columns denoted by A. B, C and D indicate the dimensions of the wheel in the corresponding regions marked A, B, C and D in fig. 32, tan say that in the right part of the table are indicated the frequencies in vibrations per second, corresponding to 2, 4, 6, 8 and 10 knots. In each horizontal row, the frequencies given correspond to the wheel whose dimensions are indicated under the headings A. B, C and D.

   Thus, it will be noted that the wheel had at the first tuning, a thickness of 3.2 cm at point A., 4.9 cm at point B, 5.1 cm at point C, Mondays (read the distance D was 6.75 cin. Referring to the second row of cliif- erers in the table, it will be noted that the only dimension modified and the one corresponding to 1) which a. been reduced by- 6.75 cin <B> he </B> G. 03 cm. This means that a section has been dotted <B> 187 </B> and 188.

   As can be seen in the table, this removal of material had the effect of reducing the frequency at four knots from 47.3 to 45.7, the frequency at six knots from 6.7 to 60.3 and the eight knot frequency from 80.3 to 78. Subsequent removal of material from the flange from the zone, as shown in the fourth row of the table, in this case consists of reducing the thickness of the flange at point A from 2.88 cm to 2.56 cm and a gradual cut towards the dimension B (it remains unaltered.

   As can be seen, the frequency at four knots was reduced from -15.7 to 42; 3, the frequency at six knots from 6 (1.3 to 58 and the frequency to (eight knots from <B> r </B> <B> 78 </B> at r 5.3.



  In the wheel thus represented in fi-. 33, the dimensions are about 3 µm in diameter, the length of the vanes in 189 about 37.5 µm and the thickness of the hub, parallel to the wheel axis, 14 cm. The wheel was intended for the 18th stage of a 35,000 XW turbine operating at 1,500 revolutions per minute.

   The nodal frequencies obtained by making the wheel vibrate at rest correspond, as has already been explained, to certain critical speeds when the wheel is rotating. The frequencies being known, these critical speeds can be determined very exactly by the above-mentioned calculation. In the case of the wheel shown in fig. 33, reducing the frequency to six knots <B> of </B> 63.2 to 58 corresponds to a reduction in the critical speed at six knots from 1446 to 1320 revolutions per minute of the wheel,

   this critical speed thus being far from the dangerous proximity of the operating speed.



  - As the chemical composition of the wheel metal, its homogeneity and other variable factors cannot be controlled absolutely exactly, it is obvious that wheels made as exactly as possible with the same dimensions, <B> differ- </B> will nevertheless be more or less @ their vibration characteristics. Each wheel should therefore be carefully tested and, if necessary, tuned according to the above principles.



  It sometimes happens that small amounts of metal can be removed from parts of wheels of a certain shape without materially influencing the natural vibration frequencies. Thus, as shown in fig. 34 which shows a partial section of a wheel, small amounts of metal may be removed from the face of the edge to which the vanes are attached, in the = ires indicated by the dotted lines 190 and 191.



  In such cases, both the stiffness and the mass are reduced to approximately the same of, d. The ratio between frequency and mass remaining substantially unaltered. there will be no change in the vibration frequency of the wheel.



  If larger amounts of metal are removed, the ratio of stiffness to mass will be altered so as to lower the frequencies of the nodal vibrations to said nodes and more, with perhaps some effect on, the vibratory frequencies corresponding to four. , six and eight knots.



  When constructing new wheels, it is evident that the data obtained in the earlier construction of wheels can be used for the study of wheels of similar dimensions and shapes. In other cases, the coefficient B can be used with a considerable degree of accuracy in calculating the critical speeds where the frequency of vibration of the wheel at rest is known. Even in these cases, however, it is advisable to check the results by subjecting both the wheel to rotation in the wheel testing machine, as described above.



  To put a wheel or wheels into vibration, in particular in the case of turbines already installed, it is appropriate to use a portable machine to vibrate, actuated with compressed air, or other means.



  The fib. 35 to 40 show a mechanical device for vibrating a turbine wheel when it is at rest, in order to determine its natural tendency to vibrate when subjected to applied forces of different frequencies.

   The device shown is well suited for use during the manufacture of turbine wheels, as well as for obtaining data from previously installed turbines, the adoption of the above-described methods. In fig. 40, 192 shows a portion of the tire of a turbine wheel and some of the vanes to which it is attached. 193 designates a connecting rod by means of which a rapid oscillating force can be applied to the wheel to make it vibrate.

   The outer end of the rod is threaded to receive the adjustable parts of a species <B> (the </B> collar comprising, in this case, a pair of wedges placed on opposite sides of the tire of the wheel and a pair of nuts, one of which 194, outside, is provided with a cross member so that it can be tightened and unscrewed by hand. The inner end of the rod is provided with a fork 195, the branches of which embrace a vibrator constituted by a vertical lever 196 (Fig. 35). The lower end of this lever enters a small block <B> 197 </B> (fig. 36) which is split on its upper side to receive it.

   Under certain conditions the block is vibrated by the lever and at other times it is hand held stationary or nearly stationary and forms a pivot support for the lever, as will be explained later. The lever and the block are freely connected together by slide and pin <B> 198 </B> and the block is resiliently supported between two layered spells 199 for a purpose described later.



  The upper end of the lever is attached to a connecting rod 200 which is vibrated by a crankpin 201 on one end of the motor shaft, a ball bearing being arranged to reduce friction. The engine, in this case an air turbine, comprises a simple impeller 202 with peripheral saw-tooth-like vanes against which compressed air is directed by means of the nozzle 203, in order to produce a rotation. The motor shaft 204 is carried in ball bearings which, in turn, are housed in bearing brackets 205 on the base plate of the machine.

   On one end of the motor shaft, a worm 206 is provided (fig. 40), a screw meshing with a helical wheel to actuate an electric generator forming part of a tachometer. The bearings of the helical wheel shaft are supported on one of the consoles - carrying the -motor., In order to prevent vibrations from the control mechanism being transmitted to the generator by its shaft, which would be inadmissible , and also to compensate for possible misalignments, there is provided a flexible coupling 208, in this case a rubber tube, connecting the adjacent ends of the shafts. The generator is held in place between the base plate and a removable caliper 209, layers of felt 210 being interposed to absorb vibrations.

   The current from the generator feeds a voltmeter 211 calibrated in speeds and with the aid of which the speed of the drive motor can be fixed and hence also the number of vibrations per unit time communicated to the turbine wheel. As previously mentioned, the lower end of the vibration lever 196 is articulated to the block 197 which is limited in the direction of its movements between two leaf springs. These springs are secured at one end to a sliding member 212 (Fig. 37) by means of a U-shaped yoke and screws.

   This member is held between guides 213 and 214 secured to the base plate and can be moved in both directions by means of the adjustment screw 215, the inner end of the screw being able to rotate freely in the member thanks to the connection. shown in fig. 38 and com carrying an ankle 216 passing through an annular groove of the screw. The limb is supported on the base by means of a flat and relatively rigid spring 217. If the leaf springs are moved to the right in fi. <B> 36 </B> and <B> 39, </B> their tension or effective action on block 197 will be increased by the fact that these springs are more rigid at their base than at their outer ends.

   Compressed air of the appropriate pressure is introduced into the engine through its nozzle 203 and supply line 218 manually adjustable by means of the throttle valve 219.



  The instructions for use of this vibration mechanism are as follows: The base plate of the mechanism will be rigidly fixed to a support adjacent to the turbine wheel which is to be vibrated; then the outer end of the connecting rod 193 will be firmly clamped on the tire of the turbine wheel. Compressed air is then admitted to the motor, the wheel of which starts to rotate and thus actuates the vibrator lever 196. On starting, the tension of the leaf springs is freely adjusted so as to be relatively low and the lever vibrates. then around its articulated connection with the connecting rod 195 as aie.

   The spring tension is then gradually increased using the adjusting screw, - e 215; with the result that the amplitude of the movements of the lower end of the vibrator lever and of the <B> 197 </B> gradually decreases and that all the force exerted by the motor is transmitted by the crankpin? 01, the connecting rod 200, the lever 196 and the rod 193 to the impeller. This rapidly acting force, first in one direction and then in the other direction, causes the paddle wheel to vibrate with a frequency depending on the speed of the engine.

   The operator then determines, either by touch or by a layer of water or granulated carbon or coarse sand, if the wheel is in a horizontal position, the number of knots or periods of vibration of the wheel under these conditions and notes the engine speed that causes these vibrations.



  As the mass of the turbine wheel to be vibrated is large, compared to that of the vibrator itself, it is difficult to switch from one nodal frequency of the wheel to another by modifying only the speed of the motor and using therefore usually the method of releasing the. tension of the springs on the block 197 until a moment when the turbine wheel has practically come to rest. The motor is then operated at a higher speed, which will give, according to experience, a higher nodal frequency than the turbine wheel; the spring tension on block 197 will then be readjusted as before until the wheel is again vibrated to a higher degree.

   This method of operation and observation is repeated until all the nodal frequencies of the wheel by these designated running conditions have been determined.

 

Claims (1)

CLAIM I: Improved rotor for a steam turbine, comprising several wheels on the same shaft, including at. at least one has a critical speed, that is to say at which oscillations are produced which become stationary in space and of appreciable amplitude, in the vicinity of the normal operating speed of the rotor, said rotor being characterized in that none of these wheels has a critical speed closer to the normal running speed than about 10% thereof, in order to prevent service disturbances due to the phenomena of 'oscillations. SUB-CLAIM 1_ An improved rotor according to claim I, in which each of the wheels is proportional to its natural vibration periods, affected by the effect of centrifugal force at the normal running speed of the rotor, in such a way that resonance conditions corresponding to four-node oscillation phenomena do not occur, at a speed which is any closer to the normal running speed of the rotor than 15% thereof, nor of its sonic conditions corresponding to phenomena of oscillations at six or eight knots at any speed closer to the normal running speed of the rotor than by 10% of this running speed. CLAIM II: A method for producing an improved rotor for a steam turbine according to claim I, characterized in that the natural vibration frequencies of each of the wheels are determined in order to free them from dangerous critical speeds and in that determine, for this purpose, for each wheel the speed of rotation at which (the phenomena of oscillations at four nodes are clearly manifested and also the corresponding speeds of rotation for the phenomena of oscillations at six and eight knots, then in that the wheel is toned or reprocessed until it no longer exhibits a critical speed corresponding to the phenomena of oscillations at four knots closer to the normal walking speed than to 15% of that -here no critical speed corresponding to oscillation phenomena at six or eight knots closer than 10 of this running speed. SUB-CLAIM 2 A method according to claim II, characterized in that one first determines the natural frequencies of oscillations of each wheel when it is at rest, then only the speed or speeds which, according to this determination, are closest to the normal running speed of the rotor.