US3572968A - Turbine bucket cover - Google Patents

Turbine bucket cover Download PDF

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Publication number
US3572968A
US3572968A US815450A US3572968DA US3572968A US 3572968 A US3572968 A US 3572968A US 815450 A US815450 A US 815450A US 3572968D A US3572968D A US 3572968DA US 3572968 A US3572968 A US 3572968A
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US
United States
Prior art keywords
tenon
buckets
bucket
cover band
adjacent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US815450A
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English (en)
Inventor
Victor S Musick
Joseph H Ouellette
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Application granted granted Critical
Publication of US3572968A publication Critical patent/US3572968A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/22—Blade-to-blade connections, e.g. for damping vibrations
    • F01D5/225—Blade-to-blade connections, e.g. for damping vibrations by shrouding

Definitions

  • This invention relates generally to turbomachinery rotors and more particularly to an improved shroud construction for rotor buckets.
  • Adjacent rotor blades or buckets are normally connected together by some form of cover bands or shroud bands around their outer periphery to confine the working fluid within a well defined path, so as not to spill outwardly past the ends of the buckets, and also to increase the rigidity of the buckets.
  • the cover bands connect groups of buckets together, a reason being that the banding of buckets into groups distributes any stimulus present in the working fluid over a group of buckets and thus decreases the stimulus acting on a single bucket.
  • One unfavorable effect of this group banding is that the cover itself can be stimulated in a resonant manner by a number of impulse frequencies corresponding to different natural vibration modes of the bucket-cover combination.
  • a large number of buckets per cover group is desirable from the standpoint of reducing the stimulus per bucket, whereas a small number of buckets per cover group is desirable to keep the number of vibrations which can be excited in a single cover segment at a minimum and also to keep the vibration spectrum at a high frequency.
  • Another object is to provide a shroud construction whereby the number of vibration frequencies which can be excited in a cover segment is kept at a minimum, and also one in which the vibration spectrum is maintained at a high frequency.
  • the present invention is practiced by a turbomachine bucket and shroud assembly wherein a tenon extends from the tip of each bucket and is provided with a step.
  • An outer cover band portion is rigidly connected to the top of the tenon step while an inner cover band portion is loosely connected to the bottom of the tenon step.
  • the cover band portions overlap one another at the tenon to provide efficient damping and at least one of the cover band portions extends to the adjacent bucket and is rigidly connected to the top of its tenon step.
  • FIG. l is an elevation showing the shroud covering in one embodiment of this invention.
  • FIG. 2 is a plan view showing the overlapping shroud covering in the same embodiment as in FIG. 1;
  • FIG. 3 is an exploded perspective view showing the detail of a bucket tip and the cover bands
  • FIG. 4 is an elevation showing the shroud covering in an alternate embodiment of this invention.
  • FIG. 5 is a plan view showing the overlapping shroud covering in the same embodiment as in FIG. A.
  • FIG. 6 is an exploded perspective view showing the detail of a bucket tip and the cover bands in the alternate embodiment.
  • FIGS. 1-3 a typical environment of this invention is shown including a plurality of buckets 2 which extend radially from a rotor (not shown). Extending radially rom the tips of buckets 2 are tenons 4 consisting of a step 5 which divides the tenon 4 into a base portion 6 and a top portion 7. This configuration of tenon 4 is provided so as to maintain proper clearances and will be more fully described in a later part of this description.
  • the inner cover or shroud generally indicated as 8 is comprised of inner cover bands 9, each. of which spans two adjacent buckets. Each inner cover band is disposed over a tenon base 6 and is constructed in such a manner as to provide circumferential clearaiice 10 between the tenon base and inner cover band.
  • a radial clearance 11 is provided between buckets 2 and inner cover bands 9 due to the configuration of tenon step 5 and thickness of cover band 9.
  • a circumferential clearance 12 is maintained between adjacent inner cover bands 9 so as to prevent a rigid coupling between buckets 2.
  • Outer cover bands 13 are constructed similarly to cover bands 9 except that there is only a small clearance for assembly purposes defined between each tenon top 7 and each outer cover band 13, that is, a substantially rigid connection between each cover band 13 and its associated tenon 4 is maintained. Upon assembly the top of tenon 4 is peened over so as to increase the rigidity of the coupling and to hold the covers on. A circumferential clearance i3a is defined between adjacent outer cover bands 13. Outer cover bands 13 are staggered with respect to the inner cover bands during assembly so that they overlap the inner cover bands 9.
  • a continuous: segmented cover band is provided consisting of over and under cover bands 14.
  • Each over and under cover band l4 extends from the tenon top 7 of one bucket to the tenon base it of the adjacent bucket.
  • an outer cover band portion is disposed over the tenon top portion 7 in a substantially rigid manner while the inner cover band portion of each over and under segmented cover band 14 is loosely disposed over the tenon base portion 6 of an adjacent bucket.
  • an outer cover band portion overlaps an inner cover band portion with the outer cover band portion extending to the adjacent bucket through a curvilinear portion 15 where it becomes an inner cover band portion which defines a clearance ll between the buckets 2 and cover bands M. Also, as in the embodiment of FIGS. 1-3, a tenon clearance 10 is provided between tenon base 6 and cover bands M.
  • each outer cover band in effect rigidly connects the two adjacent buckets, while each inner cover band in effect loosely connects two ad jacent buckets with the outer cover bands overlapping the inner cover bands.
  • the inner cover bands are forced radially outward due to the centrifugal force of rotating machinery.
  • each inner cover band together with each outer coverband fonns a semirigid bucket shroud which will, in effect, distribute any stimulus present in the working fluid flow over a large bucket group.
  • the inner and outer cover bands are not so rigidly joined that the cover itself will be stimulated in a resonant manner by a number of impulse frequencies corresponding to different natural vibration modes of the bucketcover combination. Frictional forces between bucket covers help to damp out unwanted vibrations.
  • FIGS. 4-6 The operation of the embodiment in FIGS. 4-6 is similar to the embodiment as shown in FIGS. I3 and just described except that no two buckets are rigidly joined together.
  • centrifugal force acting on the "over and under cover bands will tend to move the inner cover band portion outward toward the bottom of the next outer cover band portion due to the radial clearance 11 provided, at which point frictional and the aforementioned centrifugal force will cause the inner and outer cover band portions disposed on each tenon to form a dynamically rigid shroud.
  • a turbomachine having at least one stage of radially extending buckets and a shroud assembly extending circumferentially around the tips of said buckets, the combination comprising:
  • At least one tenon extending radially from the tip of each of said buckets and having a step with a base portion and a top portion;
  • an outer cover band portion having at least one hole therein, rigidly connected to said tenon top portion;
  • said cover band portions overlapping one another at the tenon to provide damping and at least one of said cover band portions spanning two adjacent buckets and rigidly connected to said tenon top portion of an adjacent bucket.
  • a turbomachine bucket and shroud assembly according to claim l wherein said outer cover band portion is rigidly connected to the tenon top portions of two adjacent buckets while said inner cover band portion is loosely connected between the tenon base portions of two adjacent and staggered buckets.
  • a turbomachine bucket and shroud assembly according to claim 1 wherein a cover band segment spans eve two adacent buckets and overlaps an ad acent segment at e tenon to provide said inner and outer cover band portions, one end of the segment being rigidly connected to said tenon top portion of one bucket, the other end being loosely disposed over said tenon base portion of said adjacent bucket.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US815450A 1969-04-11 1969-04-11 Turbine bucket cover Expired - Lifetime US3572968A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US81545069A 1969-04-11 1969-04-11

Publications (1)

Publication Number Publication Date
US3572968A true US3572968A (en) 1971-03-30

Family

ID=25217825

Family Applications (1)

Application Number Title Priority Date Filing Date
US815450A Expired - Lifetime US3572968A (en) 1969-04-11 1969-04-11 Turbine bucket cover

Country Status (5)

Country Link
US (1) US3572968A (de)
CH (1) CH521513A (de)
DE (1) DE2016283A1 (de)
FR (1) FR2043077A5 (de)
GB (1) GB1270203A (de)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3649133A (en) * 1970-09-10 1972-03-14 Westinghouse Electric Corp Rotor blade coupler arrangement
US3677662A (en) * 1970-10-09 1972-07-18 Avco Corp Multilayer ring damped turbomachine rotor assembly
US3756744A (en) * 1970-01-23 1973-09-04 English Electric Co Ltd Axial water flow machines
US4025232A (en) * 1973-11-27 1977-05-24 Hitachi, Ltd. Turbomachine rotor assembly
US4028006A (en) * 1975-01-24 1977-06-07 Hitachi, Ltd. Bucket cover attachment
US4401411A (en) * 1980-06-04 1983-08-30 Hitachi, Ltd. Device for connecting turbine blades
US5267834A (en) * 1992-12-30 1993-12-07 General Electric Company Bucket for the last stage of a steam turbine
US5299915A (en) * 1992-07-15 1994-04-05 General Electric Corporation Bucket for the last stage of a steam turbine
US5501573A (en) * 1993-01-29 1996-03-26 Steam Specialties, Inc. Segmented seal assembly and method for retrofitting the same to turbines and the like
US5509784A (en) * 1994-07-27 1996-04-23 General Electric Co. Turbine bucket and wheel assembly with integral bucket shroud
FR2811014A1 (fr) * 2000-06-30 2002-01-04 Framatome Sa Roue de turbine comportant un dispositif de liaison amortissant des ailettes de la roue
US6454534B1 (en) * 2000-12-21 2002-09-24 General Electric Company Flush bucket cover
CN100359136C (zh) * 2002-05-31 2008-01-02 通用电气公司 用于涡轮叶片的盖罩及其组装的方法
US20080089789A1 (en) * 2006-10-17 2008-04-17 Thomas Joseph Farineau Airfoils for use with turbine assemblies and methods of assembling the same
US20100098547A1 (en) * 2008-10-17 2010-04-22 Hagan Benjamin F Turbine blade including mistake proof feature
WO2011057622A3 (de) * 2009-11-13 2011-10-13 Mtu Aero Engines Gmbh Gasturbinenschaufel für eine strömungsmaschine
US9347326B2 (en) 2012-11-02 2016-05-24 General Electric Company Integral cover bucket assembly
US9359913B2 (en) 2013-02-27 2016-06-07 General Electric Company Steam turbine inner shell assembly with common grooves

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3842710C1 (de) * 1988-12-19 1989-08-03 Mtu Muenchen Gmbh
FR2886012B1 (fr) * 2005-05-23 2007-07-06 Snecma Moteurs Sa Procede de calibrage en masse de pieces destinees a etre montees en peripherie d'un rotor

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1129920A (en) * 1912-07-02 1915-03-02 Milton E Thompson Turbine-wheel.
US1842957A (en) * 1929-03-22 1932-01-26 Gen Electric Bridge band for blade groups of turbine rotors
GB377101A (en) * 1932-01-19 1932-07-21 English Electric Co Ltd Attaching shrouding to blades of elastic fluid turbines
US2221678A (en) * 1938-08-30 1940-11-12 Gen Electric Elastic fluid turbine bucket wheel
US3048365A (en) * 1959-12-22 1962-08-07 Curtiss Wright Corp Rotor blade shroud and vibration damping structure
US3367629A (en) * 1966-12-19 1968-02-06 Westinghouse Electric Corp Continuous shroud for rotor blades

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR321739A (fr) * 1902-06-04 1903-01-19 Parsons Foreign Patents Compan Perfectionnements apportés aux aubes de turbines à vapeur
GB344297A (en) * 1929-05-22 1931-03-05 Gen Electric Improvements in and relating to turbine wheels

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1129920A (en) * 1912-07-02 1915-03-02 Milton E Thompson Turbine-wheel.
US1842957A (en) * 1929-03-22 1932-01-26 Gen Electric Bridge band for blade groups of turbine rotors
GB377101A (en) * 1932-01-19 1932-07-21 English Electric Co Ltd Attaching shrouding to blades of elastic fluid turbines
US2221678A (en) * 1938-08-30 1940-11-12 Gen Electric Elastic fluid turbine bucket wheel
US3048365A (en) * 1959-12-22 1962-08-07 Curtiss Wright Corp Rotor blade shroud and vibration damping structure
US3367629A (en) * 1966-12-19 1968-02-06 Westinghouse Electric Corp Continuous shroud for rotor blades

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3756744A (en) * 1970-01-23 1973-09-04 English Electric Co Ltd Axial water flow machines
US3649133A (en) * 1970-09-10 1972-03-14 Westinghouse Electric Corp Rotor blade coupler arrangement
US3677662A (en) * 1970-10-09 1972-07-18 Avco Corp Multilayer ring damped turbomachine rotor assembly
US4025232A (en) * 1973-11-27 1977-05-24 Hitachi, Ltd. Turbomachine rotor assembly
US4028006A (en) * 1975-01-24 1977-06-07 Hitachi, Ltd. Bucket cover attachment
US4401411A (en) * 1980-06-04 1983-08-30 Hitachi, Ltd. Device for connecting turbine blades
US5299915A (en) * 1992-07-15 1994-04-05 General Electric Corporation Bucket for the last stage of a steam turbine
US5267834A (en) * 1992-12-30 1993-12-07 General Electric Company Bucket for the last stage of a steam turbine
US5501573A (en) * 1993-01-29 1996-03-26 Steam Specialties, Inc. Segmented seal assembly and method for retrofitting the same to turbines and the like
US5509784A (en) * 1994-07-27 1996-04-23 General Electric Co. Turbine bucket and wheel assembly with integral bucket shroud
FR2811014A1 (fr) * 2000-06-30 2002-01-04 Framatome Sa Roue de turbine comportant un dispositif de liaison amortissant des ailettes de la roue
US6454534B1 (en) * 2000-12-21 2002-09-24 General Electric Company Flush bucket cover
CN100359136C (zh) * 2002-05-31 2008-01-02 通用电气公司 用于涡轮叶片的盖罩及其组装的方法
RU2316652C2 (ru) * 2002-05-31 2008-02-10 Дженерал Электрик Компани Способ монтажа бандажа лопаток турбины
US20080089789A1 (en) * 2006-10-17 2008-04-17 Thomas Joseph Farineau Airfoils for use with turbine assemblies and methods of assembling the same
JP2008101615A (ja) * 2006-10-17 2008-05-01 General Electric Co <Ge> タービン組立体で使用する翼形部
CN101165318B (zh) * 2006-10-17 2012-10-03 通用电气公司 涡轮机组件所用翼型及其装配方法
US20100098547A1 (en) * 2008-10-17 2010-04-22 Hagan Benjamin F Turbine blade including mistake proof feature
US8435008B2 (en) 2008-10-17 2013-05-07 United Technologies Corporation Turbine blade including mistake proof feature
WO2011057622A3 (de) * 2009-11-13 2011-10-13 Mtu Aero Engines Gmbh Gasturbinenschaufel für eine strömungsmaschine
US8622704B2 (en) 2009-11-13 2014-01-07 Mtu Aero Engines Gmbh Gas turbine blade for a turbomachine
US9347326B2 (en) 2012-11-02 2016-05-24 General Electric Company Integral cover bucket assembly
US9359913B2 (en) 2013-02-27 2016-06-07 General Electric Company Steam turbine inner shell assembly with common grooves

Also Published As

Publication number Publication date
DE2016283A1 (de) 1970-10-22
GB1270203A (en) 1972-04-12
FR2043077A5 (de) 1971-02-12
CH521513A (de) 1972-04-15

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