Document
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United States Patent [191 [ I I ] Patent Number: 5,228,284
Carruthers et al.
[45] Date of Patent: Jul. 20, 1993
HIGH TEMPERATURE TURBINE ENGINE FOREIGN PATENT DOCUMENTS STRUCTURE 863432 1/1953 Fed. Rep. of Germany..
Inventors: William D. Carruthers, Mesa; Gary L.
3302323 1/1984 Fed. Rep. of Germany .
Boyd, Tempe, both of Ark.
WOA9006422 6/1990 PCT Int’l Appl. .
962057 6/1964 United Kingdom .
Assignee: Allied-Signal Inc., Morns Township, 1238405 7/1971 United Kingdom .
Morris County, N.J.
Appl. No.: 842,870 OTHER PUBLICATIONS Filed: Feb. 27,1992 Ceramic Design Methodology and the AGTlOl Tech.
Paper Mar. 1985 by Gary L. Boyd, et al.
Related U.S. Application Data Automotive Gas Turbine Ceramic Component Testing Tech. paper by Gary L. Boyd.
Division of Ser. No. 439,991, Nov. 20, 1989, Pat. No.
DOE/NASA/Ol67-82/4 “Advanced Gas Turbine 5,116,158, which is a continuation-in-part of Ser. No.
(AGT) Powertain System Development for Automo- 280,760, Dec. 6, 1988, Pat. No. 5,011,353.
tive Applications” p. 39.
Int. a . 5 ................................................ Fo2C 3/00
DOE/NASA/0167-6 “Advanced Gas Turbine (AGT) us. a. ..................................... 60/39.75; 60/753; Technology Development” p. 46.
60/39.32; 415/217.1; 415/197 DOE/NASA/OI 67-8 “Advanced Gas Turbine (AGT) Field of Search .................... 60/39.75, 753, 39.32; Technology Development” p. 30.
415/197, 200, 217.1 DOE/NASA/0167-10 “Advanced Gas Turbine (AGT) Technology Development Project” pp. 15, 16, References Cited 25, 38, 100.
U.S. PATENT DOCUMENTS DOE/NASA/OI 67-9 “Advanced Gas Turbine (AGT) 2/1976 Booher .
B 563,412 Technology Development” pp. 29, 60, 62.
808,627 1/1906 Booth .
DOE/NASA/0167-12 “Advanced Gas Turbine 845,121 2/1907 Reniff .
(AGT) Technology Development Project” pp. 207, 1,370.474 3/1921 Newsom .
252, 253.
1,407,548 2/1922 Knouff .
1,750,770 3/1930 Austin . Primary Examiner-Richard A. Bertsch 2,429.936 10/1947 Kenney .
Assistant Examiner-William Wicker 2,538,396 1/1951 Sutin .
Attorney, Agent, or Firm-Terry L. Miller; Jerry J.
2,590,175 3/1952 Hajdu .
Holden; Robert A. Walsh 3,031,049 4/1962 Somville .
3,112,547 12/1963 Poe .
P71 ABSTRACT 3,208,035 9/1965 Horvath et al. .
A high temperature ceramic/metallic turbine engine 3,316,861 S A 9 6 7 Dailey .
includes a metallic housing which journals a rotor mem- 3,835,615 9/1974 King, Jr. .
ber of the turbine engine. A ceramic disk-like shroud 3,857,649 12/1974 Schaller .
4,122,605 10/1978 Hirabayashi et a]. . portion of the engine is supported on the metallic hous- 4,312,599 1/1982 Davolia . ing portion and maintains a close running clearance 4,391,434 7/1983 LaBate .
with the rotor member. A ceramic spacer assembly 4,540,304 9/1985 Pavelka et al. .
maintains the close running clearance of the shroud 4,834,569 S A 9 8 9 Foote et al. .
portion and rotor member despite differential thermal 4,861,211 8/1989 Dunsmore .
movements between the shroud portion and metallic 4,925,364 S A 9 9 0 Das .
housing portion.
4,943,013 7/1990 Kapala et al. .
4,975,014 12/1990 Rutin et al. .
5 Claims, 4 Drawing Sheets 5,011,353 4/1991 Boyd .
U.S. Patent July 20, 1993
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In view of the deficiencies of the conventional tur- HIGH TEMPERATURE TURBINE ENGINE bine engine art, and of the materials of construction and STRUCI’URE structural techniques available for making such engines, it is a primary object for this invention to provide a The U.S. Government has rights in the present inven- 5 hybrid ceramic/metallic structure for use in a high tion pursuant to Contract No. DEN3-I 67, issued and temperature turbine engine.
funded by the Department of Energy (DOE), and ad- Particularly, it is an object of this invention to pro- ministered by the National Aeronautics and Space Ad- vide a hybrid ceramic/metallic structure wherein a ceramic portion may be disposed in a high temperature ministration (NASA).
This is a division of application Ser. No. 07/439,991 1 0 Part of a turbine engine to retain and support another filed NOV. 20, 1989, now U.S. Pat. NO. 5,116,158; which ceramic component, and to extend therefrom toward a is a continuation-in-part of application Ser. No. 280,760, lower temperature engine Part. The metalk portion of filed Dec. 6, 1988, now U.S. Pat. No. 5,011,353. the structure cooperatively interengages with the ce- This application is related to application Ser. No. ramiC portion and includes provision for engaging other which may be metallic* in order to 280,761, filed Dec. 6, 1988, now U.S. Pat. No. 4,934,138 I5 282,786, filed Dec. 9, 1988, allow relative movement between engine structures in and to application Ser. No.
expansion.
now U.S. Pat. No. 5,03 1,400, all assigned to Allied-Sig- response to More particularly, it is an object for this invention to nal Inc.
The present inventionis in the field of high tempera- provide a hybrid ceramic/metallic structure wherein a ture turbine engine structure. Particularly, the present 20 disk-like metallic portion is spaced axially from a mutu- ally concentric disk-like ceramic portion, the two Par- invention is directed to structure of a high temperature turbine engine composed of both metallic and ceramic tions experiencing differential thermal movement dur- ing operation of an engine including the structure, and components.
concentricity of the two portions being maintained A long-recognized need in the turbine engine art has 25 despite such thermal movement.
been to attain higher operating temperatures in order to Still more particularly, this invention has as an object achieve both a greater thermodynamic efficiency and the provision of a ceramic spacer structure which will an increased power output per unit of engine weight.
endure both high temperatures and physical loads while Ideally, a turbine engine should operate with stoichio- allowing differential thermal movement between a ce- metric combustion in order to extract the greatest possi- 3o ramic engine component and a metallic engine ble energy value from the consumed. However* the nent and maintaining a selected geometric relationship temperatures resulting from stoichiometric and even of these components~ near-stoichiometric combustion are beyond the endur- Further to the abve, the present invention provides ance capabilities of metallic turbine engine components. a hybrid ceramic/metallic structure a Consequently, as the turbine engine art has progressed* 35 ally extending disk-& metallic first wall member hav- an ever greater emphasis has been placed Won both ing a respective reference centerline extending perpen- enhanced cooling techniques and the development of dicularly thereof, said first wall member experiencing temperature and oxidation resistant metals for use in respective change of radial dimension in response to components of the engine which are exposed to the change of temperature thereof: a radially extending highest temperatures. That is, cooling techniques and 40 disk-like ceramic second wall member having a respec- high temperature metals have been developed for each tive reference centerline extending perpendicularly of combustion chambers, turbine stator nozzles, and thereof coaxially with said first reference centerline, turbine blades. This quest has led to the development of mid second wall member experiencing respective elaborate cooling schemes for all Of these Components change of radial dimension in response to respective as well as to classes of nickel-based “super alloy” metals 45 change of temperature thereof; spacing means for inter- which may be cast using directionally solidified Or Sin- posing axially between and engaging said wall members gle crystal techniques. All in all, the quest for higher to space the latter axially apart in mutually parallel operating temperatures in a turbine engine fabricated of relationship and maintaining coaxial alignment of metallic components has led to a still increasing corn- respective reference centerlines despite said tempera- plexity and expense in the making of the engine. 50 ture-related changes of radial dimension; and securing An alternative approach to the attainment of higher means for clamping said first and said second wall mem- operating temperatures in a turbine engine has been bers in engagement with said spacing means.
recognized. This approach involves the use of high- An advantage of the present invention resides in the of ceramic/metallic structural portions in a strength ceramic components in the engine. Ceramic provision components are better able than metals to withstand the 55 turbine engine, which portions may intersecure via the high temperature oxidizing environment of a turbine inventive spacer structure, while controlling differential engine. However, the term “high strength” in connec- thermal movements of the portions.
tion with ceramic structures must be viewed in context. Another advantage of the present invention results While many ceramic materials exhibit superior high from the use of a ceramic component in a region of the temperature strength and oxidation resistance, ceramics 60 engine exposed to high temperatures and a metallic have historically Seen difficult to employ in turbine component in a lower temperature region of the engine.
engines because of a comparatively low tensile fracture The ceramic and metallic components may be con- strength and a low defect tolerance. Consequently, a trolled in their relative movements resulting from ther- long-recognized need has been for the development of mal differences to preserve a selected alignment of the hybrid ceramic/metallic structures which utilize the 65 components.
characteristics of each material to best advantage in Additional objects and advantages of the present order to allow combustion in a turbine engine to take invention will appear from a reading of the following place closer to or at the stoichiometric level. detailed description of a single preferred embodiment of
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the invention taken in conjunction with the appended Subsequent to the exhaust duct members 48, 50 the drawing figures. flow path 18 leads to an exhaust chamber generally FIG. 1 provides a longitudinal view, partly in cross referenced with the numeral 58. A segment of some- of a hybrid ceramic/metallic turbine engine what less than 180" of the ceramic regenerator member section 5 28 is exposed to the exhaust chamber 58. Consequently, embodying the invention; FIG. 2 depicts an enlarged fragmentary cross sec- the flow path 18 leads Once again through the regenera- tional view of an encircled portion of the engine pres- tor member 28, and to ambient via the outlet 1 6 .
In order to complete this description of the engine 10, ented by FIG. 1; FIG. 3 provides a perspective schematic view of a it must be noted that in the combustor 30 fuel is added hybrid ceramic/meb]lic structure embodying the pres- 10 to the pressurized air flowing from compressor rotor 22 to support combustion. This combustion results in a ent invention; flow of high temperature Pressurized combustion Prod- 4 depicts an exploded assembly view of a hybrid FIG.
ucts flowing downstream in the 309 and in ceramic/metallic fastener and spacer assembly embody- flow path 18 subsequent to the combustor. Also, the ing the invention in perspective view; and FIG. 5 presents a fragmentary cross sectional view 15 rotor member 2 0 is joumaled in housing 12 by a journal bearing 60 disposed between the rotor portions Z2 and similar to FIG. 2 , but viewing radially inwardly, and bearing 62 disposed adja- and by a depicting an alternative embodiment of the invention.
power Output shaft portion 62 Of the cent a FIG. 1 depicts a hybrid ceramic and metallic turbine engine The engine includes a housing 12 which rotor member 20. The disk-like metallic wall portion 54 while the Outer defines an inlet 14, an outlet 16, and a tortuous flow path 2o cames the journal bearing bearing 62.
18 communicating the inlet 14 with the outlet 16 for portion 56 cames the Viewing FIGS. 2 through 4 in conjunction, it will be A hybrid cera- seen that the fastener and spacer assembly 52 includes a conveying a flow of fluid therebetween.
mic/metallic rotor member generally referenced with bolt member 66 extending through aligned apertures 68, the 2o isjoumaled in the housing l2 and 25 70, respectively defined by the turbine shroud member erates therewith to bound the flow path 18. It will be &, and by disk-like metallic wail portion 54. The bolt seen that the rotor member 20 includes a compressor member includes a head portion 72 which bears upon rotor portion 22, rotation of which inducts ambient air the turbine shroud member through an via inlet 14, as indicated by arrow 24, and delivers this ceramic washer 74. Similarly a nut portion 76 of the bolt air pressurized to a flow path section 18' as indicated by 3o member 66 bears upon the wall portion 54 through an arrow 26.
intermediate metallic washer 78. Clamped between the 18' leads axially through (view- The flow path Section ceramic disk-like turbine shroud member 46 and the ing arrow 2 6 ' ) a segment of somewhat less than 180" of disk-like metallic wall portion 54 of housing 12, is a a rotary annular regenerator member 28 which is re- ceramic tubular spacer member 80. The ceramic spacer ceived in the housing 12. Downstream ofthe regenera- 35 80 circumscribes the bolt 66, and bears at its opposite tor 28, the flow path 18 leads through an axially extend- ends on the ceramic turbine shroud 4, and upon a ing combustion structure generally referenced with the ceramic intermediate washer 82.
numeral 30 (viewing arrows 26). The combustor struc- In order to provide the reader with an overall under- ture 30 is fabricated of ceramic material and includes a standing of the turbine engine structure, FIG, 3 shows ceramic outer liner 32 which is supported at one end by 40 schematically that the disk-like ceramic turbine shroud a generally cone-shaped Outer transition member 34. A member 46 and metallic disk-like wall portion 54 are ceramic inner combustion liner 36 is Coaxially disposed spaced axially apart and intersecured by three of the within the outer liner 32, and is supported at one end on fastener and spacer assemblies 52. The wall portion 54 a ceramic transition duct member 38. The flow Path 18 defines a respective groove 84, viewing FIGS. 2 and 4, leads axially toward the one end Ofthe combustion liner 45 which is aligned radially with a centerline 86 of the wall 36, as indicated by arrow 26'. Within the transition duct portion 54. The centerline 86 is coincident with the member 38, a ceramic turbine back shroud member 40 rotational axis of the rotor 20, as determined by the and a ceramic turbine stator member 42 Cooperatively bearings 60 and 62, recalling that these bearings are define the local flow path 18, and lead the latter radially carried by walls 54 and 56. Received into the groove 84 inwardly to a ceramic turbine rotor portion 44 of the 50 are washer 82, and an end portion 88 of the spacer 80, rotor member 20. All of the transition member 3, trim- viewing particularly FIG. 4. The end portion 88 defines sition duct member 38, turbine back shroud 40, and a pair of diametrically opposed flats go,92, only one of turbine stator 42, are supported on a disk-like ceramic which is fully visible viewing FIG. 4. The flats 90, 92 turbine shroud member 46. Downstream of the turbine are closely and movably received in the groove 84 SO rotor portion 44, the flow path 18 extends axi& and 55 that the spacer 80 is nonrotational relative to the wall radially outwardly between a pair of spaced apart coop- 54. Consequently, the grooves 84 intersecting at center- erative ceramic exhaust duct members, respectively line 86 establish a radial action line 94 for the spacers 80, referenced with the numerals 48 and 50. A plurality of viewing FIG. 3 . That is, each of the spacers 80 are able in the grooves 84 in a respective axially extend- hybrid ceramic/metallic fastener and spacer members to rock generally referenced with the numeral 52 (one of which 60 ing radial plane containing the lines 94. These action is visible in FIG. 1) cooperatively engage the turbine line planes intersect at the centerline 86.
shroud 46 and the housing 12. The exhaust duct mem- Viewing FIGS. 2 and 4, it will be seen that the spac- bers 48, 50 are cooperatively supported by the turbine ers 80 each defme opposed end surfaces %, 98 which shroud 46 and fasteners 52. A disk-like metallic wall are cylindrically crowned about the center of the spacer portion 54 of housing 12 supports the fasteners 52. Wall 65 80. That is, the crown surfaces %,98 present to turbine portion 54, in cooperation with a metallic outer wall shroud 46 and wall 54 portions of a right circular cylin- portion 56 of housing 12, defines the flow path 18' drical surface having a diameter equal to the length of downstream of compressor rotor portion 22. spacer 80. The disposition of the crown surfaces %, 98
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is such that the cylindrical centerline of these surfaces is Because the surfaces 104, 106 are further apart than perpendicular to the action lines 94. surfaces 96, 98, the change in angulation of the bolt 66 Viewing the schematic depiction of FIG. 3 once is expected to be less than the angulation change of again, it is shown that each spacer 80 may be visualized spacer 80. However, the angulation changes of both 66 as a cylindrical roller or rocker 100, depicted in phan- 5 and spacer 80 are in the same direction so that a rela- tom lines, which is disposed between the wall 54 and tively small clearance 108 is sufficient to prevent inter- turbine shroud 46. The line along which each roller will ference between the bolt and spacer.
roll in response to local relative radial movement is the Received closely about the spacer 80 is an annular 110. The action line 94. These action lines 94 intersect at the ring-like secondary ceramic spacer member 10 secondary spacer member 110 spaces apart the exhaust centerline 86 of both the turbine shroud 46 and wall 54.
During operation of the turbine engine 10, the ceramic duct members 48 and 50. Cooperatively, the three sec- 46 and metallic wall 54 experience ondary spacer members 110 camed upon the three turbine shroud changes in temperature, and resulting radial growth or fastener and spacer assemblies 52 substantially maintain contraction. These temperature responsive growths and concentricity of the exhaust duct members 48, 50 with contractions may be in phase with one another, possibly 15 both the turbine shroud 4 6 and wall portion 54. That is, the secondary spacer member 110 includes an axially at different rates, or they may be out of phase with one extending boss portion 112 which cooperates with the another. In other words, the members 46, 54 may be remainder of the secondary spacer to define a shoulder expanding or contracting together at different rates, or 114. The duct member 48 is circumferentially continu- one may be expanding while the other is contracting.
Consequently, the members 46, 54 experience local 20 ous at its outer perimeter and includes three peripheral relative radial movement during operation of the tur- portions 116, only a portion of one portion 116 being visible in FIG. 2, each radially confronting a boss 112.
bine engine 10. These local relative radial movements The duct member 48 is captured between the turbine are represented by arrows 102. Despite these local ra- dial movements, the centerline 86 of turbine shroud 46 shroud 46 and shoulder 114, and is located concentri- 25 cally by the radial cooperation of the three bosses 114 at must remain substantially coincident with the centerline of wall 54. This coincidence of centerlines must be the three peripheral portions 116 similarly to the turbine preserved because the running clearance between the shroud 46. In a like manner, the exhaust duct member 50 is circumferentially continuous at its outer perimeter turbine shroud 46 and turbine rotor 44 is very small, and the bearings for rotor 20 are carried by the metallic and includes three peripheral portions 118, only a por- walls 54 and 56. Thus, concentricity of these structural 30 tion of one portion 118 being visible in FIG. 2. The portions 118 respectively confront one of the spacers 80 elements must be preserved despite the local radial movements 102. This necessary concentricity is pre- thereby to preserve concentricity of the duct member served by allowing free radial relative movement of the 50. A resilient member 120 urges the duct member 50 into engagement with secondary spacer 110 to bias the members 46,54 at the location of spacers 80 along action 35 latter and duct 48 toward turbine shroud 46. Because lines 94 coincident with rolling of the rollers 100 (rock- movement of spacers 80 is limited to rocking substan- ing of spacers 80), while preventing relative circumfer- ential movements at these spacers. Viewing FIG. 3, it is tially in an axially extending radial plane in response to easily appreciated that local circumferential relative local relative radial movements between shroud 46 and 54, the concentricity of the ducts 48 and 50 is pre- movements between members 4 6 and 54 are prevented wall 40 served by the cooperation of the three fastener and so long as there is no slippage between these members spacer assemblies 52 with the peripheral portions 116, and the cylinders 100 (spacers 80). While the spacers 80 118.
are in fact not a full cylinder, like phantom cylinders FIG. 5 depicts an alternative embodiment of the in- 100, these spaces present cylindrical surfaces at 96,98 to the members 46, 54, respectively, and function as cylin- vention. In order to obtain reference numerals for use in 45 describing this alternative embodiment of the invention, drical rollers for limited radial relative movements.
features which are analogous in structure or function to Viewing once again FIG. 2, it is seen that the bolt those described above are referenced with the same member 66 engages members 46 and 54 through the intermediate washers 74 and 78. Each of these washers numeral used above, and with a prime added thereto.
FIG. 5 shows a cross sectional view similar to FIG. 2, defines a respective cylindrical crown surface 104,106, 50 but with the direction of view being radially inwardly.
having its center at the center of the spacer 80. In other words, all of the cylindrical surfaces 96, 98, 104, 106, The metal wall 54' of the turbine engine 10' supports a ceramic turbine shroud 46' through a fastener and ideally have the same centerline at the center of spacer spacer assembly 52'. The bolt 66' and nut portion 76' of 80. Because of the compressive clamping force applied by the bolt members 66, the ceramic crown surfaces 96, assembly 5 2 are the same as that described above. Simi- 98 frictionally engage the ceramic turbine shroud 46 55 larly, the crown washers 74,78', spacer W', and washer and ceramic washer 82 for rocking motion substantially 82' received in groove 84' are the same as that described above. However, the embodiment of FIG. 5 includes an without slippage. The spacer member 80 defines a radial clearance 108 with the bolt 66 so that binding or inter- advantageous cooperation between the secondary spac- ference does not result from the relative angulation of ers 110' on spacers 80' and the turbine shroud 46' both the spacer and bolt as the former rocks between the 60 to assure retention of Concentricity for the turbine shroud, and to allow for manufacturing tolerances in shroud 4 6 and wall portion 54. On the other hand, the components of the engine 10'.
crown surfaces 104, 106 allow the bolt 66 to assume As depicted in FIG. 5, the ceramic turbine shroud 46' angulated positions deviating slightly from a perpendic- ular between the shroud 46 and wall 54 as these local defines a radially extending groove 122, which parallels 65 the groove 84' in wall 54'. The ceramic secondary features move radially relative to one another. This spacer member 110' includes an axially elongate boss change in angulation of bolt 66 results in a rocking portion 112' cooperating with the remainder of the motion at the head 72 on crown surface 96, and at nut 76 spacer 110 to define a shoulder 114 upon which sets on crown surface 98, without slippage therebetween.
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the duct wall 48’. The boss portion 112’ also extends combustion providing a flow of high temperature pres- into the groove 122 so that outer diametral surfaces 124 surized combustion products in said flow path down- of the boss portion 112’ movingly engage the turbine stream thereof, said rotor member including a turbine shroud with only a slight clearance. Finally, the boss rotor portion disposed in said flow path downstream of portion 112’ is intentionally made eccentric with respect 5 said combustor and rotatively expanding said combus- to the bore of spacer llO’, whereat the spacer 80’ is tion products toward ambient for flow from said turbine closely received. That is, the outer diametral surface engine via said outlet, said turbine rotor portion provid- 124 is slightly eccentric with respect to the bore of ing shaft power driving said compressor rotor portion spacer llO’, and the spacer 80’.
and an output shaft portion of said rotor member, a During assembly of the turbine engine 10, a fixture is 10 disk-like metallic housing portion journaling said rotor employed in place of the rotor 20 to set concentricity of member to define a rotational axis therefor, and a disk- turbine shroud 46’ with the bearings 60, 62. As a result like annular ceramic turbine shroud member bounding of manufacturing tolerances, the radial grooves 122 in said flow path downstream of said combustor and cir- shroud 46‘ may not have perfect circumferential align- cumscribing said turbine rotor portion to define a run- ment with the radial grooves 84 of the metallic wall 54’. 15 ning clearance therewith, said disk-like ceramic turbine Minor circumferential misalignments are accommo- shroud member having a reference axis coaxial with dated by relative rotation of the spacer 110 on spacer 80 said rotational axis and being spaced axially from said until the boss portion 112’ is received into its respective metallic housing portion in mutually parallel concentric groove 122’ of shroud 46’. Of course, minor radial mis- relation therewith and a plurality of spacers disposed alignments are accommodated by the free radial rock- 20 between ceramic disk-like shroud member and said inimovement of the spacer 80- Once the bolt 66‘ is metallic disk-like housing portion and circumferentially tightened by operation of nut portion 76’, the primary spaced apart, each of said spacers having a first and mechanism for retention of alignment and concentricity second end portion having an end surface adjacent said is rocking contact without slippage, as described above.
shroud member and said housing portion respectively, However, in the event of a severe transverse accelera- said end surfaces having a cylindrical curvature extend- tion or G-force such as would shift the shroud 46‘ rela- ing transversely relative to said shroud member and said 54, the surfaces 124 cooperate with shroud tive to wall housing portion, and a plurality of securing means for 46‘ at grooves 122 to add further retention strength.
intersecuring said housing portion and shroud member The applicants have built and tested both embodi- into contact with each of said cylindrically curved end ments of the invention herein described. In both cases 3 0 surfaces, whereby said coaxial relation of said rotational acceptable concentricity was maintained between the axis and said reference axis is preserved despite changes ceramic turbine shroud and metallic housing during in radial dimensions of said housing portion and shroud thermal cycling. Additionally, the embodiment of member as results from thermal expansion.
FIGS. 1-4 was subjected to lateral acceleration forces 2. The invention of claim 1 wherein said spacers are on a shaker table up to a level of 8G’s with satisfactory 35 equally spaced circumferentially apart at substantially retention of concentricity. In fact, the test article had no 120” separation.
measurable loss of concentricity after the shaker table 3. The invention of claim 2 wherein each of said episode. It should be apparent to those ordinarily skilled spacers is tubular and defines a bore extending between in the pertinent art that the cylinder axes of the rollers said housing portion and said shroud member.
100 each define one side of an equilateral triangle. Three 4. The invention of claim 3 wherein said plurality of rollers is the minimum number necessary to maintain securing means are elongate bolt members each passing concentricity of the walls 56 and 54. However, a greater through respective axially aligned holes defined by each number of cylinder rollers 100 (spacers 80) can be used.
of said turbine shroud member and housing portion, In this case, each cylinder axis will define one side of a each of said bolt members also passing through one of regular plane polygon having a number of sides equal to 45 said bores, said bolt members clamping said housing the number of roller members.
portion and said shroud member into engagement with What is claimed is: said spacers.
1. A hybrid ceramic/metallic gas turbine comprising; 5. The invention of claim 4 further including a pair of a housing defining an inlet, an outlet, and a flow path cylindrically crowned washers received upon each one communicating said inlet with said outlet-for conveying of said bolt members and interposing at opposite ends a flow of fluid through said housing, a rotor member thereof between axially disposed abutment surfaces of journaled by said housing in said flow path, said rotor said bolt members and respective one of said housing member including a compressor rotor portion rota- tively inducting ambient air via said inlet and delivering portion and shroud member, said washers each having a this air pressurized to said flow path downstream of said 5 5 cylindrical crown surface cylindrical with respect to a cylinder axis midway between said housing portion and compressor rotor, a combustor disposed in said flow path downstream of said compressor receiving said shroud member.
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pressurized air along with a supply of fuel to maintain