US3370830A

US3370830A - Turbine cooling

Info

Publication number: US3370830A
Application number: US601067A
Authority: US
Inventors: Lawrence H Nickles; John E Harper
Original assignee: General Motors Corp
Current assignee: Motors Liquidation Co
Priority date: 1966-12-12
Filing date: 1966-12-12
Publication date: 1968-02-27
Anticipated expiration: 1985-02-27
Also published as: GB1126020A

Description

United States Patent 3 O 3,370,830 TURBINE COOLING Lawrence H. Nickles, Allestree, Derby, England, and John E. Harper, Greenwood, Ind., assiguors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 12, 1966, Ser. No. 601,067 7 Claims. (Cl. 253-3915) ABSTRACT OF THE DISCLOSURE Air-cooled turbine blades are mounted on a turbine rotor, the rotor rim and blade roots defining communicating passages for cooling air. A tube mounted within the passages and extending into both the rotor and the blade root minimizes leakage through the gap between the rim and root. The tube is retained by being lodged against shoulders at the bottoms of counterbores in-these two structures, one end of the tube being flared or expanded so that it cannot fall out of the hole through which it is originally moved into place.

Our invention in one aspect relates to turbines and particularly to structure for feeding cooling air or other cooling agents to turbine blades. In another aspect, the invention relates to an improved connection between two bodies such, for example, as a turbine rotor and a rotor blade to conduct a fluid and to reduce or minimize leakage. In still another aspect, our invention may be regarded as an improvement in the retention of tubes interconnecting two structures.

In the preferred embodiment of the invention air-cooled turbine blades are mounted on a turbine rotor, the rotor rim and blade roots defining communicating passages for cooling air. A tube mounted within the passages and extending into both the rotor and the blade root minimizes leakage through the gap between the rim and root. The tube is retained by being lodged against shoulders at the bottoms of counterbores in these two structures, one end of the tube being flared or expanded so that it cannot fall out of the hole through which it is originally moved into place.

The principal objects of the invention are to improve the efficiency of turbine rot-or cooling, to provide a connection minimizing leakage in the transfer of fluid from a rotor or structure to a blade more or less loosely mounted on the rotor, and to provide a fluid conducting structure which is simple and easily installed and which is safe against dislodging. A further object is to provide an improved method of completing an installation of the character referred to. The nature of our invention and its advantages will be apparent to those skilled in the art from the succeeding detailed description and accompanying drawings of preferred embodiments of the invention.

FIGURE 1 is a partial sectional view of a turbine rotor wheel and a blade mounted thereon, the section being taken on a plane containing the axis of the wheel.

FIGURE 2 is an enlarged fragmentary view illustrating a first step in the fitting of the interconnecting tube.

FIGURE 3 is a similar view illustrating a further step.

FIGURE 4 is a similar view illustrating the final or swaging step in the assembly.

FIGURE 5 is a view similar to FIGURE 4 illustrating modifications of structure.

Referring first to FIGURE 1, a turbine wheel 9 having a rim 10 mounts a ring of blades 11. Each blade includes a platform 13, a stalk 14, and a root 15. The blade root is mounted in an appropriate slot 17 in the rim; as illustrated, the root and slot are of the well-known multiple ICC dovetail type. Sealing plates or rings 18 and 19 extending around the rotor between the rim and the blade platforms serve to enclose the space between the ring of blade platforms and the rim. Each blade includes an entry passage 21 for cooling air extending from the base of the root into a chamber 22 within the blade from which it is discharged through any sort of openings in the blade or in the outer shroud 23 of the blade. The structure of the blade is immaterial to our invention. The cooling air reaches the passage 21 through a passage 25 in the rim aligned with passage 21, to which it is supplied by any suitable means (not illustrated).

Referring now to FIGURE 2 which shows the structure to larger scale, the passage 25 is defined by a bore 26 and a counterbore 27 of slightly larger diameter than bore 26. The passage 21 is defined by a counterbore 29, preferably approximately the same diameter as counterbore 27, and by a bore 30 of smaller diameter than bore 26. While there may be some departure from a coaxial relation between the several bores and counterbores, preferably they are all coaxial. This structure provides a shoulder 31 within the rim and a shoulder 33 within the blade root. Since the blades normally are mounted somewhat freely in the slot, there is typically a clearance at 34 between the base of the blade root and the bottom of the slot in the rotor.

According to our invention, this gap is bridged, by a short tube 37 which, as indicated in FIGURES 2, 3, and 4, is introduced through the bore 26 which is large enough to allow the tube to enter freely. Tube 37 preferably is just long enough to reach from shoulder 31 to shoulder 33 when it has been pushed into place. As illustrated in FIGURE 3, the diameter of bore 30 is preferably approximately the same as the interior diameter of the tube so that the upper end of the tube lodges against the shoulder 33. The tube is retained, and a sealing relation to the rotor is preferably created, by swaging or expanding the tube, as shown in FIGURE 4. A punch 38 having a conical point 39 and of such diameter as to slide freely within the bore 25 is introduced against the rim end of tube 37 and is driven slightly into the tube with a hammer or other instrument so that the rim end of the tube is swaged outwardly, as indicated at 41 in FIGURE 4. This swaging enlarges the tube so that it cannot drop out of the passage 25 and also preferably seats the outer wall of the tube firmly against the circumferential wall of the counterbore 27.

Note that the swaged portion does not extend into the blade root, and the major part of the tube has some clearance from the blade root and rim. Thus, the tube does not interfere with some shifting of the blade in response to forces acting upon it. In other words, the tube 37 is not a blade locking pin. The blade root may be retained by any suitable known structure as, for example, by the sealing rings 18 and 19.

The angle of the point 39 of the punch is not critical, but an angle of about 60 is preferred. The material of the tube 37 may vary depending upon the temperature level which it must withstand in operation of the turbine. Since the tube 37 closely abuts the shoulder 33 and the shoulder 31 and also preferably is in a rather tight fit within the counterbore 27, leakage through gap 34 is minimized. It will be seen that it is contemplated that the difference in radius between the

bores

25 and 27 is approximately the thickness of the tube 37. The end 39 of punch 38 may be used to insert the tube as well as to expand it.

FIGURE 5 illustrates two modifications. In this case, the structure of the rim 10 is the same as that previously described and the blade root 15' may differ only in that the shoulder 33 is conical.

FIGURE 5 also illustrates a punch 38 which adds a feature to the punch previously described in that the body .of the punch-is steppediqap iovide a shoulder 43 which engag -sti e m .101 cont ol the, depth o ns rt n o the tool.

The foregoing descriptionof preferred embodiments of The ease of installation of the tubes 37 ,isobvious. The blade maybe removed upon disassembly of the rotor by shearing the tube 37 by movement of the blade root in its slot.

The detailed description of the preferred embodiment of the invention for the purpose of explaining the principles thereof is ,notto be considered as limiting or restrict ing the invention, as many modifications may be made by the exercise of skill in the art.

We claim:

1. A structure for directing 'a fluid from a first body in o et ond y compri ing, .inecombination:

a first body, V

a second body juxtaposed to the first body, and

.a tubeextending into both bodies;

the first body having a bore of larger diameter than the 'norrnal outside diameter of the tube and having a counterbore, substantially coaxial with and ,ofgreater diameter than the bore, extending to the surface of the body adjacentto thesecond body,

the second body having a bore of smaller diameter than the normal outside diameter of the tube and having a counterbore larger than the normal outside diameter of the tube aligned with the .counterbore in the first bo y, V

4 t the tube being seated aaginst the bottom of the counterbore inthe second body and having a radially expanded end retained in the counterbore in the first body. 7 V

2. A structure as recitedin claim 1 in which the radially expanded end is seated againstthe bottom of the counterbore in the first body. Y V

3. A structure as recited in claim 1 in which the radially expanded end is expanded into a close fit with the circumferential wall of the counterbore.

4. A structure as recited in claim 3 in which the radially expanded endis seated against the bottom ofthe counterbore in the first body.

5. A structure as recited in claim 1 in which one of the bodies is a blade-mounting part of a turbine and the other is a turbine blade.

6. A structure as recited in claim 1 in which one of the bodies is a turbine rotor and the other is a turbine blade.

7. A structure as recited in claim 1 in which the first body is a turbine rotor and the second body is a turbine blade root.

References Cited UNITED STATES PATENTS 2,930,580 3/1960 Hayes 25339.15 2,931,623 4/1960 Hyde 25339.15 3,219,314 11/1965 Petrie 253--39.15 3,295,826 1/ 1967 Nickles 253'--77 EVERETT A. POWELL, JR., Primary Examiner.