US3857649A

US3857649A - Inlet vane structure for turbines

Info

Publication number: US3857649A
Application number: US00387069A
Authority: US
Inventors: R Schaller; S Leshnoff
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1973-08-09
Filing date: 1973-08-09
Publication date: 1974-12-31
Anticipated expiration: 1991-12-31
Also published as: NL7409924A; JPS5044309A; DE2437486A1; DE2437486C2; SE392147B; IT1017716B; JPS5228168B2; CH585845A5; FR2240355B1; CA995141A; FR2240355A1; GB1470989A; SE7410246L

Abstract

An improved inlet vane structure for axial flow turbines, comprising a plurality of ceramic vanes extending radially outward from an inner shroud ring and supported at their outer end by a blade ring. The vanes are held in a compressed state by spring mounted within the outer ends of a vane support structure. Tapered vane end caps, which are also constructed of ceramic materials, mate with the vanes and provide additional compressive forces on the vanes when the vanes are loaded due to fluid flow.

Description

United States Patent 1191 I t 1111 3,857,649-

Schaller et a1. [4 Dec. 31, 1974 1 INLET VANE STRUCTURE FOR TURBINES FOREIGN PATENTS OR APPLICATIONS 1 1 InvenwrSI Richard Swan", Ambler, Pad 826,673 11/1951 Germany 415/214 Stephen D. Leshnoff, Highland Park, 57,426 4/ 1902 France NJ. 1,136,350 9/1962 Germany 415/160 [73] Assignee: .Westinghouse Electric Corporation,

1 Pittsburgh p Primary Examiner-C. J. 1-1usar Assistant ExaminerLou1s J. Casaregola [22] Fled: U73 Attorney, Agent, or Firm-D. N. Halgren [21] Appl. No.: 387,069

[57] ABSTRACT [52] US. Cl 415/200, 415/137, 415/214, An improved inlet vane structure for axial flow tur- 415/217 bines, comprising a plurality of ceramic vanes extend- [51] Fold 9/00, Fold 9/02, Fold 25/26 ing radially outward from an inner shroud ring and [58] Field of Search 415/191, 214, 200, 212, Supportedat their outer end by a blade ring The 115/177, 140,191,1601416/22l241 vanes are held in a compressed state by spring mounted within the outer ends of a vane support 1 Remfllces Cited structure. Tapered vane end caps, which are also con- UNITED STATES PATENTS structed of ceramic materials, mate with the vanes and 2,801,076 7/1957 Terrell et a1. 4151200 Provide additional Compressive forces on the vanes 3,025,037 3/1962 Beckstrom 415/177 wh n h vanes r lo ded due o fluid flow 3,619,077 11/1971 Wile et a1. 415/214 0 3,719,427 3/1973 Davis 415/160 3 Clam, 4 Drawmg Flgures l 1 2 1 36 :I I '1 i I 34 1 1 PATENTEDBEU 1- I974 SHEET 1 BF 2 FIG! ILL

FIGZ

N lll 3 2 4 x I 5 24 l Ill]: I I'll E \l 8 [I] E l 5 I H 6 I I ll. 8 S J 3 mum 1 INLET VANE STRUCTURE FOR TURBINES The invention herein described was made in the course of or under a contract or subcontract thereunder with The Department of the Army.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to turbines-and more particularly to a support assembly for maintaining first row ceramic inlet guide vanes in a compressed state.

2. Description of the Prior Art The temperatures at which turbines operate are constantly being increased to increase the efficiency of the turbine. Raising the operating temperature and hence the efficiency of a turbine also means increasing the temperature of the fluid at the inlet nozzle of the turbine. Present inlet nozzles will only function until a certain maximum temperature is reached, then if the efficiency is to be further improved, the inlet structure must be cooled or materials that can withstand higher temperatures must be utilized in the nozzle. Cooling the inlet nozzles require special equipment to create the cooling effect. The power requirements of this special cooling equipment will, however, decrease the efficiency gained by the higher inlet fluid temperatures.

Another method of allowing increasing temperatures at the nozzle inlet is to construct the structure from materials that will withstand the high temperatures. Ceramics have long been known to withstand high temperatures, and ceramics are structurally strong when they are utilized in a compressed state. An inlet nozzle structure of ceramics which is maintained in compres sion would obviate the need for both a cooling effect on the nozzles, and the need for cooling equipment.

German Patent No. 826,673, issued in January, 1952, shows a turbine inlet being guided by radially directed compressive springs. The springs are used to hold the inlet in circular alignment, and are not utilized to prevent failure of the ceramic inlet nozzle by reducing noncompressive forces.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided an improved inlet vane structure for a gas turbine. Springs are disposed radially outwards of stationary ceramic inlet vanes and end supports. The springs compress the inlet vanes, through the vane end supports, and allow for aslight pivotable movement during turbine operation. An alternative embodiment of the inlet guide vanes is comprised of ceramic guide vanes that are tapered in the axially downstream direction, that mate with supporting ceramic end caps tapered correspondingly; wherein a downstream flow of fluid would wedge the vane into the end caps creating additional compressive forces within the structure.

BRIEF DESCRIPTION .OF THE DRAWINGS inward direction taken along the line III-III in FIG. 2;

and

FIG. 4 is a perspective view of an alternative embodiment of a vane and end caps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in detail, and particularly to FIG. 1, a portion of a gas turbine 10 is shown by a side view of its inlet nozzle arrangement 12. The inlet nozzle 12 includes an inner shroud ring 14 which has a plurality of circumferentially disposed cooling fluid passageways 16 that allows'a cooling fluid to impinge upon an inner supporting structure 17.

The inner supporting structure 17 includes a plurality of hemispherically-shaped pivot studs 18 circumferentially disposed on the radially outward side of ring 14. The studs 18 each pivotably mate with a convex hemispherically-shaped nobule 20, providing the inlet nozzle arrangement 12 with a slight freedom of movement. A pair of the nobules 20 are attached to the radially inward side of each ofa plurality of circumferentially disposed inner metal shoes 22. The inner metal shoe 22 is in turn, disposed radially inwards of, and supports an insulator pad 24. Each metal shoe 22 has a radially outwardly directed lip member 26 as shown in FIG. 2, on one of its ends to prevent the insulator pad 24 from moving in a circumferential direction. A jambolt 28 extends through ring 14, engages and further restrains the insulator pad 24.

An inner ceramic end cap 34 is disposed on the radially outward side of insulator pad 24. The end cap 34 is permitted a slight circumferential motion with respect to insulator pad 24 because of a tongue 30 and groove 32 arrangement therebetween. The track-like components, the tongue 30 in cap 34 and the groove 32 in insulator pad 24 thereby also provide a slight circumferential movability to the entire inlet structure 12.

Each inner end cap 34 has a substantially axially disposed groove 35. Each groove 35 secures the inner end of a radially extending air foil vane 36. Each air foil vane 36 is similarly secured on its radially outward end by a groove 37 in an outer end cap 38.

The support structure radially outward of the air foil vane 36 is similar to that radially inward of the vane 36, except that a compressive inducing means is disposed outwardly of vane 36.

Each outer end cap 38 has a tongue arrangement 40 which is similar to that of-inner end cap 34. The tongue 40 slidably interlocks with a circumferentially disposed groove 42 on the radially inward side of each outer insulator pad 44. The outer tongue 40 and groove 42 arrangement contributes to the circumferential movement allowable in nozzle inlet structure 12. Each outer insulator pad 44 is disposed in an outer metal shoe 50. The pad 44 is restrained from-circumferential motion by engagement witha jambolt 46 that extends through an outer support ring 48 and by a radially inwardly directed lip 51 as shown in FIG. 2 on one end of shoe 50. The outer shroud ring 48 is coaxial with inner support ring 14, and the two

rings

14 and 48 provide the containment for the nozzle.

A cooling fluid passageway 49 is directed through the outer shroud ring 48 to allow cooling fluid to impinge upon each outer metal shoe 50.

Each outer shoe 50 has a convex hemisphericallyshaped outer nobule 52 attached to its radially outward side. A radially directed plunger 54, has a concave hemispherically-shaped inner end 56 that supports and cooperatively associates with outer nobule 52 to permit shoe 50 to have a movable interface with respect to said plunger 54. The plunger 54 is slidably held in its radial direction by a sleeve member 58 that is integral with and supported by, outer shroud ring 48.

A bias producing spring member 60 cooperates with plunger 54 to providea radially inwardly directed compressive force upon

inlet nozzle members

34, 36 and 38, which are constructed from ceramic materials. The compressive force upon these

ceramic members

34, 36 and 38 prevents the inlet structure from failing under extremely high temperatures.

As is shown in FIG. 2, each outer insulator pad 44 retainstwo vane outer end caps 38 and 38'. Each inner insulator pad 24 likewise retains two inner end caps, 34

and 34. Each end cap, 34 and 38, supports an end of only one air foil vane 36.

The radially directed lip members, 26 and 51, extending off one end inner shoes 22and outer shoes 50 respectively, are shown in- FIG. 2, each restraining their respective insulator pads, 24 or 44, from circumferential motion.

A portion of the outer ring member 48 is shown in the radially inwardly directed view of FIG. 3.

The ceramic elements of this invention are shown in an alternative embodiment of FIG. 4. An inner end cap 62 is shown tapered to increasing thickness in the downstream direction. Cap 62 has a circumferentially disposed tongue 64 on its radially inward side similar to the tongue arrangement 30 of inner-end cap 34 shown in FIG. 1. End cap 62 has an inclined plane 68 in which a serpentine round bottomed groove 66 is disposed. A ceramic air foil vane 72 has a correspondingly rounded radially inner end 70 that mates with groove 66 and matches its configuration. The ceramic air foil vane 72 is tapered to decreasing downstream lengthwise dimensions, and has a radially outer end .74 that is rounded similar to inner end 70. A ceramic outer end cap 80 is disposed radially outwardly of the mates with the radially outward end'74 of vane 72 through a serpentine round bottomed groove 76 disposed on an inclined plane 78 of cap 80 similar to that-of inner end cap 62.

' The outerceramic end cap 80 inclined in the direction of increasing thickness downstream has a tongue 82 arrangement similar to that of outer end cap 38 shown in FIG. 1.

The inner and outer round bottomed

grooves

66 and 76 cooperatively mate with the inner and outer rounded ends 70 and 74 of the radially directed tapered ceramic air foil vane 72. The configuration allows the air foil vane 72 to move relative to the end caps 62 and 80. The ceramic components, the vane 72, and end caps '62 and 80 will have minimum stress concentrations that would be caused by thermal expansion, mismatch, imperfectly joined parts, or notch effects.

Compressive forces, however, generated in this embodiment are compounded because the working fluid moving in the downstream direction imparts a load upon the vane 72 wedging it into

end caps

62 and 80,

in addition to the compressive forces caused in the structure by the spring bias producing member 60.

Ceramic materials of the type used in this invention aregencrally silicon nitride Si N,, or silicon carbide SiC. Their desirability comes from the fact that the raw materials are very inexpensive, that they can withstand very high temperatures and they resist most forms of deterioration.

The detailed description of the preferred embodiments of the invention is not to be considered as limitingor restricting the invention, as many modifications may be made by those skilled in the art.

We claim:

1. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring coaxial with said radially inner shroud ring. a plurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure,

said inner support structure comprising a ceramic end cap, an insulator pad and an'inner shoe plate disposed on said inner shroud ring,

said outer support structure comprising a ceramic end cap, an insulator pad, an outer shoe plate and a bias producing means,

said outer shoe plate being movable connected to said bias producing means, said bias producing means reacting cooperatively with said outer ring, wherein said bias producing means provides a compressive force directed radially inwardly on each of said ceramic structures,

said bias producing means consists of a rod-like plunger cooperatively associated with a spring member to induce a compressive force upon said ceramic structure, said plunger having a hemispherical surface on its inner end to provide a movable interface with respect to said outer shoe which has a mating hemispherical surface.

2. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring coaxial with said radially inner shroud ring, a plurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure,

said inner structure comprising a ceramic end cap, an insulator pad and aninsulator plate disposed on said inner shroud ring,

said outer shoe plate being movably connected to said bias producing means, said bias producing means reactingcooperatively with said outer ring, wherein said bias producing means provides a compressive force directed radially inwardly on each of said ceramic structures,

said end caps having rounded grooves, said end caps having increasing thickness in the downstream direction, said vanes having'their inner and outer ends rounded to mate with said rounded grooves in said end caps, to provide additional compressive forces on said ceramic structures due to the fluid load upon said vanes in thedirection of elastic fluid flow.

3. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring, aplurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure,

said inner support structure comprising an inner ceramic end cap,

said outer support structure comprising an outer ceramic end cap,

lationship therebetween,

Claims

1. An inlet nozzle for a gas turbine comprising: a radially inner shroud ring, a radially outer shroud ring coaxial with said radially inner shroud ring, a plurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure, said inner support structure compRising a ceramic end cap, an insulator pad and an inner shoe plate disposed on said inner shroud ring, said outer support structure comprising a ceramic end cap, an insulator pad, an outer shoe plate and a bias producing means, said outer shoe plate being movable connected to said bias producing means, said bias producing means reacting cooperatively with said outer ring, wherein said bias producing means provides a compressive force directed radially inwardly on each of said ceramic structures, said bias producing means consists of a rod-like plunger cooperatively associated with a spring member to induce a compressive force upon said ceramic structure, said plunger having a hemispherical surface on its inner end to provide a movable interface with respect to said outer shoe which has a mating hemispherical surface.

2. An inlet nozzle for a gas turbine comprising: a radially inner shroud ring, a radially outer shroud ring coaxial with said radially inner shroud ring, a plurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure, said inner structure comprising a ceramic end cap, an insulator pad and an insulator plate disposed on said inner shroud ring, said outer support structure comprising a ceramic end cap, an insulator pad, an outer shoe plate and a bias producing means, said outer shoe plate being movably connected to said bias producing means, said bias producing means reacting cooperatively with said outer ring, wherein said bias producing means provides a compressive force directed radially inwardly on each of said ceramic structures, said end caps having rounded grooves, said end caps having increasing thickness in the downstream direction, said vanes having their inner and outer ends rounded to mate with said rounded grooves in said end caps, to provide additional compressive forces on said ceramic structures due to the fluid load upon said vanes in the direction of elastic fluid flow.

3. An inlet nozzle for a gas turbine comprising: a radially inner shroud ring, a radially outer shroud ring, a plurality of radially extending ceramic vane structures disposed between said radially inner and said radially outer shroud rings, each of said vanes being secured at one end to said radially inner shroud ring by an inner support structure, each of said vanes being secured at its other end to said radially outer shroud ring by an outer support structure, said inner support structure comprising an inner ceramic end cap, said outer support structure comprising an outer ceramic end cap, said vanes being tapered to decreasing downstream lengthwise dimensions, said vanes having generally rounded ends, said end caps being tapered to increasing downstream radial dimensions, wherein said taper of said end caps matches the taper of said vanes, said end caps having rounded generally axially directed grooves, said rounded ends of said vanes mating with said rounded grooves in said end caps to provide a slight pivotable yet generally compressible supporting relationship therebetween.