Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
  • F16J15/08—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing
  • F16J15/0806—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing characterised by material or surface treatment
  • F16J15/0812—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing characterised by material or surface treatment with a braided or knitted body
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
  • F02K9/08—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using solid propellants
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
  • F02K9/08—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using solid propellants
  • F02K9/32—Constructional parts; Details not otherwise provided for
  • F02K9/34—Casings; Combustion chambers; Liners thereof
  • F02K9/343—Joints, connections, seals therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
  • F16J15/064—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces the packing combining the sealing function with other functions
  • F16J15/065—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces the packing combining the sealing function with other functions fire resistant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
  • F05D2300/614—Fibres or filaments

Definitions

• the invention relates to solid propulsion rocket engines and more specifically the production of the connection between rear end of combustion chamber and nozzle.
• Such a connection comprises a mechanical assembly, at least in the axial direction, between the bottom and the nozzle and the production of a seal against combustion gases at the interface, or joint, defined between the adjacent facing surfaces of the bottom and of the nozzle.
• Sealing is usually achieved by at least one O-ring, generally two: a primary seal and a secondary seal arranged in series in the interface.
• Seals are traditionally made of an elastomeric material which cannot withstand durably without damage to the temperature of the combustion gases produced in the chamber.
• a thermal barrier is introduced into the interface between the end of the latter situated on the interior side of the chamber and the seals in order to cool the combustion gases which have entered the interface before they may come into contact with the primary seal.
• the thermal barrier is commonly constituted by a layer of grease.
• this layer of grease could, in certain cases, leave a sufficient passage for the combustion gases for them to reach the primary seal while still being at too high a temperature.
• the object of the invention is to remedy this drawback by proposing a more efficient thermal barrier.
• This object is achieved by a connection between the rear bottom of the combustion chamber and the rocket engine nozzle of the type comprising mechanical connection means connecting the nozzle to the bottom at least in the axial direction, as well as a thermal barrier and at least one seal. sealing disposed in the interface defined by the adjacent facing surfaces of the bottom and of the nozzle, connection in which, in accordance with the invention, the thermal barrier comprises at least one texture of refractory fibers forming a bead wound in the interface around the longitudinal axis of the chamber, the cord or cords being produced so as to ensure circumferential continuity of the thermal barrier.
• bead (s) of refractory fibers for example carbon and / or ceramic, makes it possible to give the thermal barrier good resistance to the temperature of the combustion gases.
• the or each bead may be in the form of a braid or of superimposed two-dimensional fibrous strata, for example layers of fabric.
• the achievement of the fibrous texture (braid or layers) and its degree of compaction in the interface determine the permeability of the thermal barrier to gases, the object being to impose on the gases a time of crossing of the thermal barrier sufficiently long to ensuring sufficient cooling of these, the fibrous texture taking heat from the gases to transmit it to the walls between which it is enclosed.
• the effect of the thermal barrier is reinforced by placing the bead or cords in a part of the interface forming a baffle on the path of combustion gases liable to creep into the interface.
• a baffle causes an elongation of the path of the combustion gases and avoids direct exposure of the thermal barrier to radiation from the combustion chamber.
• the circumferential continuity of the thermal barrier can be ensured in various ways.
• the thermal barrier comprises at least two separate cords, the ends of one of the cords occupying with respect to the axis of the chamber angular positions different from those of the ends of the other cord.
• the thermal barrier comprises at least one cord wound in a helix extending over more than the interface circumference. The use of one or more closed continuous cords can also be considered.
• the thermal barrier is disposed in the bottom-nozzle interface between the end of the latter located on the inside of the combustion chamber and one or more seals.
• the thermal barrier in another embodiment, in particular when the thermal barrier is in the form of a fibrous texture compacted in the interface, in particular at the level of a part of the interface forming a baffle, the thermal barrier can also form a gasket. seal.
• the mechanical connection means comprise at least one annular axial locking piece partially housed and retained in a groove formed on the outside of the bottom and on which an end surface of the nozzle rests. .
• Such a mechanical connection means represents an important simplification compared to the use of screws, as in the prior art.
• the axial locking piece is a split annular piece, the establishment and withdrawal can be achieved by elastic deformation.
• the mechanical connection means comprise a rod in several sectors held in place by a clamp.
• FIG. 2 is an enlarged view showing a first embodiment of a connection according to the invention between rear end of combustion chamber and nozzle in a rocket engine such as for example that of Figure 1;
• - Figure 3 is a detail view showing an example of winding a cord forming a thermal barrier in the connection of Figure 2;
• FIGS. 4 and 5 are detail views showing two embodiments of the cord forming the thermal barrier in the connection of Figure 2;
• FIG. 10 is a view similar to that of Figure 6 showing another embodiment of the mechanical connection between bottom and nozzle.
• FIG. 1 shows in a simplified manner an arrangement of a rear part of a solid propulsion rocket engine.
• the rocket engine comprises a combustion chamber 10 delimited by an envelope 12 which ends, at the rear of the chamber, by a rear bottom 14.
• a nozzle 20 is connected to the bottom 14.
• the nozzle is orientable by pivoting with respect to the longitudinal axis A of the combustion chamber.
• the assembly formed by the convergent 20a, the neck 20b and the divergent 20ç is mounted on an annular support piece, or heel 22, by means of a spherical articulation stop 24.
• the stop 24 is for example of the laminated abutment type formed by stacking spherical layers alternately rigid metallic layers and elastomer layers adhered to each other.
• the stop 24 is isolated from the interior of the combustion chamber by a membrane 26.
• Activation means for example jacks (not shown) mounted on the casing 12 and acting on an activation ring on the outside of the divergent, make it possible to give the axis of the nozzle, therefore the direction of ejection of the combustion gases, a desired orientation relative to the axis A.
• the heel 22 is fixed relative to the casing 12 and is connected to the rear bottom 14.
• Mechanical connection means (not shown in FIG. 1) axially connect the heel 22 to the bottom 14.
• the bottom 14 and the heel 22 are assembled along an interface or joint 30 defined by the facing surfaces of the heel 22 and the bottom 14 and which extends substantially in the axial direction between the inside and the outside of the combustion chamber.
• the interface 30 is provided with seals protected by a thermal barrier (not shown in FIG. 1).
• FIG. 2 A rear rocket engine arrangement as briefly described above is well known per se.
• the field of application of the invention is of course not limited to rocket motors with orientable nozzle but also includes those with fixed nozzle.
• An embodiment of a connection according to the invention between the rear end 14 and the nozzle heel 22 in a rocket engine such as for example that of FIG. 1 is illustrated in detail by FIG. 2.
• the bottom 14 comprises an outer wall 14a, for example metallic, provided on the inner side with a thermal protection 14b, for example made of elastomer, in a manner known per se.
• the nozzle heel 22 includes an external wall 22a, for example metallic, which corresponds to and extends the wall 14a from the bottom, and an internal thermal protection 22b, for example made of elastomer, which prolongs the thermal protection 14b the bottom.
• the interface 30 has a non-rectilinear profile, in axial (or meridian) section, the surface of the heel 22 bordering the interface 30 having a diameter which varies non-decreasingly along the interface 30 from the end of that -this located on the inside of the combustion chamber.
• a seal or, preferably, for safety reasons, at least two respectively primary 32 and secondary 34 seals are arranged in series in the interface 30.
• the seals 32 and 34 are each formed by an O-ring made of elastomeric material.
• Each joint is housed in an annular groove, respectively 36, 38, formed in one of the surfaces facing the bottom 14 and the heel 22, in the example illustrated that of the heel 22, and is compressed by application of the other area.
• the seals 32 and 34 are spaced from the end of the interface 30 located on the inside of the combustion chamber, preferably located in the part of the interface 30 bordered by the metal walls 14a and 22a.
• a thermal barrier 40 is disposed in the interface 30 between the end of the latter situated on the interior side of the chamber and the seals 32, 34.
• the thermal barrier 40 is for example situated in the part of the interface 30 bordered by thermal protections 14b and 22b, but is advantageously distant from the interior end of the interface to avoid its premature destruction during the erosion of thermal protections 14b, 22b by the combustion gases.
• the thermal barrier is therefore close to the metal walls 14a, 22a. It could be housed in the interface part 30 located between these metal walls 14a, 22a.
• the thermal barrier 40 comprises a cord 42 of refractory fibers, for example carbon fibers which is wound between recesses 14c and 22c formed in the walls facing the bottom 14 and the heel 22.
• the cord 42 is wound over more than one turn around the axis A so that the continuity of the thermal barrier in the axial direction is not interrupted at the ends of the cord.
• the winding of the cord 42 is for example carried out over approximately two turns, as shown in FIG. 3.
• the continuous cord 42 forms two adjacent circular turns.
• the part 42c connecting the two turns passes between the ends 42a and 42b of the cord.
• the ends 42a and 42b are shaped to minimize the circumferential play between the part 42c and these ends.
• the cord 42 is for example constituted by a braid of carbon fibers as shown in FIG. 4.
• the recesses 14c and 22c are produced so as to provide a housing for the cord 42 while carrying out a compression of the latter, limiting its permeability to gases.
• the recesses 14c, 22c give the part of the interface 30 where the thermal barrier is located a form of baffle.
• This baffle profile combined with the limited permeability of the cord 42, prevents rapid passage of the thermal barrier by the combustion gases entering the interface 30 from the combustion chamber.
• the gases finally passing through the thermal barrier can then be sufficiently cooled in contact with the walls opposite the bottom 14 and the heel 22 before reaching the primary seal 32.
• the crossing of the thermal barrier by the combustion gas allows them to ensure pressurization of the primary seal 32 for good efficiency of this seal.
• the walls of the recesses 14c, 22c which enclose the cord 42 are radial. They could be conical. Fibrous structures other than a braid can be used to make the bead of the thermal barrier.
• FIG. 5 shows a cord 42 ′ formed by superposed fibrous strata each constituted by a strip of two-dimensional fibrous texture, for example a strip of carbon fabric.
• the superimposed strata are folded over the length of the cord, which gives them a U-shaped profile.
• the open side of the U is arranged in the interface 30 so as to be oriented towards the end of the latter situated on the inner side of bedroom. In this way, combustion gases coming into contact with the cord 42 ′ tend to apply its longitudinal edges to the facing surfaces delimiting the interface 30.
• cord 42 in carbon fibers
• other refractory fibers can be used, for example ceramic fibers.
• the cord 42 can be maintained, for example, by interposing a layer of grease or by localized bonding.
• the mechanical connection between the bottom 14 and the nozzle heel 22 can be carried out in a known manner by screws. In the example illustrated, and more simply, it is produced by means of a locking piece 50 (FIG. 2).
• the part 50 is in the form of a split metal ring with an L-shaped section, one wing 50a of which is partially housed in a groove 52 formed in a surface 14d of the bottom extending on the external side that delimiting the interface 30.
• the nozzle heel 12 has a radial end surface 12d which is supported on the part of the wing 50a projecting from the groove 52.
• the other wing 50b of the part 50 is supported on the surface 14d for compensate for the bearing force of the heel 22 on the wing 50a.
• the part 50 can be put in place or removed by elastic deformation in the circumferential direction.
• the blocking in axial direction of the nozzle heel 22 relative to the bottom 14 is achieved by the locking piece 50 in combination with localized non-axial supports between surfaces of the bottom 14 and the heel 22 bordering the interface 30.
• FIG. 6 illustrates an alternative embodiment of the thermal barrier 40 of FIG. 2.
• the cord 42 of refractory fibers is wound in a helix between two helical recesses 14e and 22e formed in the walls opposite the bottom 14 and the heel 22.
• the cord 42 is wound over more than one turn around the axis A so that the continuity of the thermal barrier in the axial direction is not interrupted at the ends of the cord.
• FIG. 7 illustrates another alternative embodiment of the thermal barrier 40 of FIG. 2.
• a helical groove 22f for example with a V section, is formed in a radial recess 22g from the surface of the nozzle heel 22 bordering the interface.
• the cord 42 is wound around the axis A in the groove 22f and is enclosed between the wall of the latter and a radial offset 14g from the surface of the bottom 14, bordering the interface 30, corresponding to the offset 22g.
• the recesses 14g and 22g give a baffle shape at the interface 30 at the thermal barrier.
• FIG. 8 illustrates another alternative embodiment of the thermal barrier 40 of FIG. 2.
• a helical groove 22h for example of V section, is formed in an axial wall part 22i of the surface of the nozzle heel 22 bordering the 'interface 30.
• the cord 42 is wound around the axis A in the groove 22h and is clamped between the wall thereof and an axial wall portion 14i of the surface of the bottom 14 bordering the interface 30.
• the figure 8 does not show a baffle shape for the interface 30 at the thermal barrier. However, such a chicane can be created by recesses in the walls of the surfaces facing the bottom 14 and the heel 22 in the immediate vicinity of the location of the cord 42.
• FIG. 9 illustrates yet another alternative embodiment of the thermal barrier 40 of FIG. 2.
• the thermal barrier comprises two circular beads 42 ⁇ , 42 2 arranged in series and close to one another in the interface 30.
• the cord 42 ⁇ is housed at the connection between an axial part 22 ⁇ of the surface of the nozzle heel 22 bordering the interface 30 and a radial recess 22k of this same surface. It is enclosed between the surfaces 22j, 22k and a portion of conical wall 14k of the surface of the bottom 14 bordering the interface 30.
• the cord 42 2 is wound in a groove 221 for example with a V section, formed in an axial part of the surface of the nozzle heel 22 bordering the interface 30. It is sandwiched between the walls of the groove
• the cords 42 ⁇ and 42 2 each completely surround the axis A.
• the ends of the cord 42 ⁇ are angularly offset from those of the cord 42 2 to maintain the continuity of the thermal barrier in the axial direction.
• the thermal barrier may also constitute a seal, so that the primary seal 32, or even the two seals 32 and 34 could be omitted. This can be more particularly the case when the thermal barrier is a bead formed of compressible fibrous texture wound over more than one turn while being compressed in the interface 30, in particular when the bead is placed in one or more housings formed in a baffle. of interface 30.
• FIG. 10 illustrates another embodiment of the mechanical connection between the bottom 14 and the nozzle heel 22, the elements common between this embodiment and that of FIG. 2 having the same references.
• a plurality of locking pieces in the form of ring sectors are used.
• Each 50 'piece has a profile in L similar to the part 50 of FIG. 2, with a wing 50'a which is partially housed in the groove 52 formed in the surface 14d of the bottom 14 and a wing 50'b taking its internal face bearing on this surface 14d .
• the nozzle heel 22 rests on the wings 50 ′ of parts 50 ′.
• Each piece 50 extends over an angle which does not exceed 180 ° and is held in place by a snap ring 54. This is fixed by screws 56 to the nozzle heel 22 and is supported on the external face wing 50'b.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Gasket Seals (AREA)
• Combustion Methods Of Internal-Combustion Engines (AREA)
• Air Supply (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)

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• 2002
  • 2002-12-02 FR FR0215158A patent/FR2847945B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-01 WO PCT/FR2003/003538 patent/WO2004053320A2/fr not_active Ceased
  • 2003-12-01 BR BR0316787-9A patent/BR0316787A/pt not_active IP Right Cessation
  • 2003-12-01 JP JP2004558142A patent/JP2006508296A/ja not_active Withdrawn
  • 2003-12-01 UA UAA200505240A patent/UA81643C2/ru unknown
  • 2003-12-01 EP EP03796117A patent/EP1567761A2/de not_active Withdrawn
  • 2003-12-01 RU RU2005116972/06A patent/RU2330172C2/ru not_active IP Right Cessation
  • 2003-12-01 AU AU2003298377A patent/AU2003298377A1/en not_active Abandoned
• 2005
  • 2005-05-30 IL IL168861A patent/IL168861A/en not_active IP Right Cessation

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