US2510606A - Turbine construction - Google Patents

Description

June 6, 1950 N. c. PRICE 2,510,696

- TURBINE cons'muc'non Otiginal Filed llay 22, 1943 IN VEN TOR.

NATHAN 0. PRICE Agent Patented June 6, 1950 2,510,606 TURBINE CONSTRUCTION Nathan C. Price, Los Angeles, Califqassignor to Lockheed Aircraft Corporation, Burbank, Calif.

Original application May 22.,- 1943, Serial No. 488,029, now Patent No. 2,468,461, dated April Divided and this application Februv ary 28, 1945, Serial No.- 580,241

10 Claims. (Cl. 253- 78) This invention relates to turbines, and has more particular reference to the mounting and securing of turbine blades or vanes. This application is a division of my copending application, Serial No. 488,029, filed May 22, 1943, issued as Patent No. 2,468,461, April 26, 1949, which is a continuation in part of my copending application, Serial No. 433,599, filed March 6, 1942.

The high temperatures existing in the expansion zones of gas turbines necessitate special provision for the mounting of the blading rows. The intermediates or stator vanes must be rigidly secured in predetermined positions on the turbine housing but allowance must be made for the differential expansion and contraction of the housing and vane mounting elements in directions both radially and circumferentially of the assembly. Furthermore, it is desirable that the surfaces between the adjacent vanes and between the rows of vanes be smooth and uninterrupted, and that there be means for cooling or insulating the blade-supporting parts and housing.

It is a general object of the present invention to provide a gas turbine construction embodying simple, yet effective, means for mounting the turbine vanes. The construction of the present invention is particularly well suited for the mounting of stator vanes or intermediates on the internal wall of the turbine housing and is such that it does not require a special housing construction. The turbine housing may be a simple structure presenting'a plain cylindrical inner surface for receiving the vane mounting members.

It is another object of the invention to provide a turbine vane mounting means which assures accurate maintained rigid attachment of the vanes to the housing, while at the same time allowing for thermal expansion and contraction differential of the vane-attaching plates and the housing. The invention provides annular series of segmental plates, each carrying two or more vanes and attached to the turbine housing in such a manner that they may expand and contract under varying thermal conditions and yet remain rigidly secured to the housing.

invention is to provide Anotherobject of the a turbine vane mounting arrangement of the character mentioned that is simple and inexpensive to fabricate and install. The plurality of segmental vane mounting plates for each row of vanes may be identical to reduce manufacturing costs and the several plates are secured to 2 the housing by simple rivet means of like or identical character to simplify installation.

It is a further object of the inventionto provide a turbine vane mounting means incorporating cooling or insulating air spaces between the wall of the turbine housing and substantial areas of the vane supporting plates, which spaces communicate with the interiors .-cf the hollow vanes.

Other objects and features of the invention will be readily understood from the following detailed description of a typical preferred form of the invention wherein reference will be made to the accompanying drawings in which:

Figure 1 is a fragmentary longitudinal section of a portion of a gas turbine embodying the construction of the invention;

Figure 2 is an enlarged fragmentary longitudinal section illustrating the blade mounting means; and

Figure 3 is a view of one of the blade mounting plates taken substantially as indicated by line 3-3 on Figure 2.

The construction of the present invention is suitable for use in turbine machines of widely different classes and may be modified to adapt it for specific applications. I will herein describe the invention in connection with a gas turbine of the type embodied in the internal combustion reaction type power plants more fully described in my copending applications above referred to, it being understood that this disclosure is not to be construed as limiting either the scope or application of the present invention.

The portion of the gas turbine illustrated in Figure 1 includes a. combustion chamber 0 terminating at its rear end in a restricted discharge nozzle ring Hi. The rotor R of the turbine is carried by a rotatable shaft II, which in turn is carried by a suitable bearing l2. The rotor R is hollow and frusto-conical and the bearing I2 is supported in the reduced forward portion of the hollow rotor by a tapering tubular support member Ill. The housing ll of the turbine is a cylindrical tubular member secured to the combustion chamber housing by bolts or screws IS. The turbine housing It extends axially in spaced surrounding relation to the rotor R to leave an annular expansion zone l6 of rearwardly increasing capacity. The rotor R carries rows of buckets or blades l1 projecting radially into the expansion zone is and the nozzle ring In discharges the heated gases into the forward end of the zone for action on the rotor blades. A baflle l8 3 is arranged between the interior of the hollow rotor R and the bearing supporting member 13 to direct cooling air along the interior of the rotor and into contact with the roots of the bladw [1. The present invention is not primarily concerned with the structure thus far described except insofar as its elements are present in combination therewith.

The construction of this invention may be said to comprise generally turbine intermediates or stator vanes 20, 2|, 22 and 23, attaching or mounting plates 25 for the vanes, and means 25 for securing the plates to the turbine housing.

The stator vanes 20 to 23 are fixed or-stationarily mounted on the wall of the housing I! by the attaching means of the invention and are arranged in circumferentially extending rows. The rows of stator vanes are between the rows of rotor blades H as shown in Figure 1. The blades or vanes are graduated in size, the vanes 23 of the rearward row being both wider and longer than the blades 20 of the foremost row. It is preferred to construct the stator vanes of a heat resistant metal or alloy and to make the blades hollow for cooling purposes and to reduce their weight. As best shown in Figures 2 and 3, each vane may have an extensive internal cavity 9 which is closed at the free extremity of the vane and open at the root end. The intermediates or stator vanes may be of selected or required configuration. In the case illustrated the vanes are cambered and are substantially airfoil shaped in transverse cross section. The vanes are pitched with respect to the longitudinal axis of the turbine assembly and the pitch of the vanes, or at least the pitch of the vanes in a given row, is uniform.

The mounting plates or members 25 serve to carry the stator vanes and the members are in turn secured to the housing I by the means 25 to be subsequently described. Each plate member 25 preferably serves to carry a number of vanes; for example, it may supportthree vanes as shown in Figure 3. The plate members 25 may be similar in shape and construction and the members for supporting a given row of vanes are preferably identical to reduce manufacturing costs. However, owing to the graduated size of the vanes, the plate members of each row will usually be of different dimensions than the plate members of the other rows. The plate members 25 for a given row of stator vanes are cylindrically curved segments of an annulus, the cylindrical curvature being such that the members may closely conform to the internal surface of the housing H. The circumferential edges of the plate members 25 are preferably straight and parallel. The root portions of the vanes are received in openings 21 in the plate members 25 and are welded to the members'at 23. As best shown in Figure 2, the outer faces of the plate members, that is, the faces which oppose the inner surface of the housing I, are relieved to have recesses 30. The vane roots and the welds 28 are received in these spaces or recesses 30. Longitudinal or circumferential ribs 4| may be provided on the plate members 25 to extend through the recesses 30 for the purpose of reinforcing the members. The ends of the segmental plate members may be axial with respect to the longitudinal axis of the turbine assembly, but where the stator vanes are pitched as shown, it is preferred to make the ends diagonal so as to leave ample stock beyond the endmost vanes carried by each member. It is to be understood that the vanes are rigidly fixed to their respective plate members to project substantially radially into the expansion zone ll of the turbine.

In accordance with the invention, the plate members 25 for the addacent rows of vanes 20 to 23, are constructed and related to be in overlapping relation along their circumferential edge portions. The circular edge parts of the plate members 25 are stepped or provided with of!- sets 3! and 32. One circumferential edge of each member is stepped back from its inner surface to provide an oil-set 3|, while the opposite edge is stepped back from its outer surface to provide the off-set 32. The recesses above referred to are spaced from the circumferential edges of the plate members to leave ample stock at the oil-sets 3| and 32. The off-sets 3| and 32 are formed so that the plate members 25 of adjacent rows overlap one another whereby the assembly presents a smooth, regular and substantially unbroken cylindrical surface which constitutes the outer wall of the expansion zone l5. As best illustrated in Figure 2, the overlapping off-set portions of the plate members 25 are proportioned to leave small clearance spaces between the edges of the members and the offsets. These spaces allow for differential thermal expansion and contraction of the assembly in the axial direction.

It is preferred to relate the vane carrying plate members 25 so that the diagonal joints between the members of one row fall out of alignment with the diagonal joints of the adjacent rows. The recesses 30 communicate with the interiors of the hollow vanes and the several recesses of a given row are in communication with one another to constitute an annular cooling space or air space at the roots of the vanes in.that row. The reinforcing ribs ll and the circumferential edge portions of the plate members 25 bear against theinternal surface of the housing H.

The means 25 for securing the vane-carrying plate members 25 to the housing ll is characterized by its simplicity and by the fact that it maintains the rigid attachment of the members to the housing and yet allows for differential thermal expansion and contraction of the housing and plate members. Each plate member 25 is provided along one circumferential margin with a plurality of spaced rivet openings 34. There are preferably three and not more than four rivet openings in each member. Further, it is preferred to form the openings in those marginal portions of the plate members which carry. the outer oil-sets 32. Rivets are introduced into the openings 34 and have their heads countersunk at the exposed inner surfaces of the plate members. I have found it desirable to weld the rivets in their openings 34 to facilitate assembling of the members in the housin It and to prevent movement of therivets in the plate openings during differential expansion and contraction of the members and housing. The rivets 35 are passed outwardly through openings 35 in the wall of the housing M and their outer ends are set-up or headed over.

The rivet connections are such that each plate member 25 is free for circumferential expansion and contraction with respect to the housing M. The openings 36 in the housing for receiving the endmost rivets 35 of each plate member 25 are elongated circumferentially, as at 81 in Figure 3, to allow relative circumferential movement between the housing 14 and the end portions of the plate members during differential expansion and 8 contraction of the housing and members. The intermediate rivet or rivets 35 of each plate member 25 are preferably tightly set-up while the outervrivets are left loose enough to permit the required differential movement. The loose setting of the outer rivets 35 may be elected by installin paper washers 38 on the rivets and then up-setting the rivets onto the washers. It is preferred to employ hollow rivets as shown in Figure 2 to facilitate up-setting of the rivets on the paper washers and to prevent swelling of the shanks in the elongated openings 31. Upon the initial heating of the gas turbine the washers 38 char and fall away, leaving the rivets loose in the openings 30 of the housing ll. The clearance in the spaces and joints of the vanecarrying plate assembly need only be suiflciently great to allow for differential thermal expansion and contraction under maximum temperature conditions of intended turbine operation.

It is believed that the features of the invention will be readily understood from the foregoin detailed description. The vane-supporting plate members 25 are simple inexpensive parts and the welding of the vanes to the members is a readily performed operation. Likewise, the riveting of the members 25 to the inner wall of the turbine housing H is a simple operation and does not require special detailed construction of the housing. During turbine operation the differential thermal expansion and contraction of the plate members 25 and the housing ll cause no ill effects because the clearance spaces at 3| and 32 and the clearance in the elongated housing openings 31 allow relative movement between the housing and the members suflicient to compensate for such differential expansion and contraction. The rivets 35 being fixed to the members 25 cannot tip or move inwardly to reduce the impeller blade tip clearance. Further the fixed rivets in the elongated openings 31 assist in guiding the plates circumferentially during differential expansion and contraction of the parts. The plate members 25 form an effective substantially complete temperature resistant and insulating lining "for the pressure-resisting housing M. The protective function of the plate members 25 is of special importance where the turbine wheel R is air cooled as above described. Where the wheeLR and the housing I are both protected against excessive temperatures the diametral and axial clearances of the stator and impeller vanes are not materially aifected by temperature changes. The recesses 30 of the adjacent members 25 form continuous annular air spaces which assist in cooling the parts and in insulating the housing l I. It will be observed that the assembly does not necessitate any projections or irregularities on the exposed surface of the housing ll.

Having described only a typical form of the invention, I do not wish to be limited to the speciilc details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

I claim:

1. In a turbine, a housing presenting a curved inner surface, an annular series of segmental plates conforming to said surface of the housing, the plates of said series having clearance one with the other to allow for thermal expansion and contraction, vanes secured to the plates to project inwardly therefrom, and means for attaching the plates to the housing, there being openings in the wall of the housing, said means including securing members on the plates received in said openings, certain of said openings being proportioned to allow movement of the securing members therein, thereby allowing for differential thermal expansion and contraction of the housing and plates.

2. In a turbine a housing presenting a curved inner surface, an annular series of segmental plates conforming to said surface of the housing, there being clearance between the adjacent plates of said series sufficient to allow thermal expansion and contraction of the plates, vanes secured to the plates to project inwardly therefrom, there being openings in the wall of the housing, and means for securing the plates to the housing including end and intermediate securing members on the plates engaged in said openings, the openings which receive the end securing members receiving said members with clearance to allow differential thermal expansion and contraction of the housing and plates.

3. In a gas turbine the combination of two 2 elements, one a housing having a curved inner surface, the other a plate curved to conform to said surface, said elements being proportioned and related for differential thermal expansion and contraction, one element having a series of openings, securing members on the other element extending through said openings and having heads cooperating with said other element to attach the plate to said surface, certain of said members serving to secure end portions of the plate to the housing, the openings which receive said certain members being proportioned to receive the members for movement therein and the heads of said certain members normally being spaced from said other element thereby permitting differential thermal expansion and contraction of the housing and plate, and at least one vane carried by the plate.

4. In a turbine, a housing presenting a curved inner surface, an annular series of segmental plates conforming to said surface of the housing, the plates of said series having clearance one with one another and being related to the housing for independent thermal expansion and contraction, vanes secured to the plates to project inwardly therefrom, there being openings in the wall of the housing, and means for securing the plates to the housing including end and intermediate securing members on the plates engaged in said openings, the openings which receive the end securing members receiving said members with clearance to allow differential thermal expansion and contraction of the housing and plates, said securing members being spaced along one circumferential margin of each plate thereby allowing differential. thermal expansion and contraction of the housing and plate in a direction axially of the housing.

5. A turbine construction comprising a housing of generally tubular form having a curved inner surface, a plurality of circumferentially extending rows of segmental plates on said inner surface, a row of vanes carried by each row of plates, stepped marginal portions on the plates,

- said stepped portions of the plates of adjacent rows being in overlapping relation with clearance therebetween to allow relative movement in a direction axially of the housing, and rivet means for securing the plates to the housing only along one circumferential margin of each plate, the plates being otherwise unsecured to allow differential thermal expansion and contraction of the housing and plates in the axial direction.

6. A turbine construction comprising a housing of generally tubular form having a curved inner surface, a plurality of circumferentially extending rows of segmental plates on said inner surface, a row of vanes carried by each row of plates, stepped marginal portions on the plates, said stepped portions of the plates of adjacent rows being in overlapping relation with clearance therebetween to allow relative movement in a direction axially of the housing, and means for securing the plates to the housing along only one circumferential margin of each plate, the plates being otherwise unsecured to allow differential thermal expansion and contraction of the housing and plates in the axial direction, the plates being secured to the housing along corresponding margins.

7. A turbine construction comprising a housing of generally tubular form having a curved inner surface, a plurality of circumferentially extending rows of segmental plates on said inner surface, a row of vanes carried by each row of plates, stepped portions extending along the circumferential margins of the plates, said portions of the plates of adjacent rows being in overlapping relation, raised ridges of limited axial extent on the peripheries of the plates for engaging said surface of the housing, said. ridges being spaced apart axially to define recesses in the peripheral faces of the plates which form ,air spaces between said surface of the housing and substantial areas of the plates, and means adjacent said marginal portions of the plates for securing the plates to the housing.

8. A turbine construction-comprising a housing of generally tubular form having a curved inner surface, a plurality of circumferentially extending rows of segmental plates on said inner surface, the peripheral faces of the plates having circumferentially extending recesses, the recesses of the plates in each row being incommunication with one another to constitute annular air spaces between said surface and the rows of plates, relatively narrow lands extending along the margins of the recesses for contacting said inner surface of the housing, hollow stator vanes, means for securing the plates to the housing, and means for attaching the vanes to the plates so that their interiors communicate with said annular spaces.

9. In a turbine, a housing presenting a curved inner surface, an annular series of segmental plates conforming to said surface of the housing, said plates having clearance one with the other and being related to said surface for independent thermal expansion and contraction, vanes secured to the plates to project inwardly therefrom, there being openings in the wall of the housing,

' temperatures.

10. A counter-vane means for arrangement in a generally cylindrical turbine casing comprising a vane for extending radially in the casing, a base member fixed to the root of the vane, the base member having the form of a segment of an annulus and having an external surface curved cylindrically to engage and conform with the inside surface of the turbine casing, oil-sets on the opposite circumferentially extending edges of the base member adapted to have flush overlapping engagement with the edges of adjacent base members, the casing having spaced openings at only one Of said edges of the base member, and attaching parts extending through said openings to secure the base member to the casing, said parts and said overlapping engagement constituting the only means for attaching the base member to the casing.

NATHAN 0. PRICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 735,054 Bentley Aug. 4, 1903 779,910 Curtis Jan. 10, 1905 972,421 Westinghouse Oct. 11, 1910 1,154,777 Kieser Sept. 28, 1915 1,325,135 Baumann Dec. 16, 1919 1,362,437 Robb Dec. 14, 1920 1,726,104 Harris Aug. 27, 1929 1,873,743 Doran Aug. 23, 1932 2,073,605 Belluzzo Mar. 16, 1937 2,149,510 Darrieus Mar. 7, 1939 2,241,782 Jendrassik May13, 1941 2,247,423 Webster, Jr. July 1, 1941 2,366,142 Allen Dec. 26, 1944 2,468,461 \Price Apr. 26, 1949 FOREIGN PATENTS Number Country Date 212,654 Germany Aug. 6, 1909 243,974 Great Britain Dec. 10, 1925 272,459 Great Britain Sept. 1, 1927 374,689 Great Britain June 16, 1982

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