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Publication numberUS3806275 A
Publication typeGrant
Publication dateApr 23, 1974
Filing dateAug 30, 1972
Priority dateAug 30, 1972
Publication numberUS 3806275 A, US 3806275A, US-A-3806275, US3806275 A, US3806275A
InventorsAspinwall R
Original AssigneeGen Motors Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cooled airfoil
US 3806275 A
Abstract
A hollow air-cooled turbine blade has a web extending from face to face of the blade to divide the interior of the blade into two spanwise-extending chambers. A thin sheet metal liner is disposed in each chamber, the liner having perforations distributed over its surface and having projections to space it from the blade wall. The liner is flexible and may be folded substantially flat for insertion into the end of the blade. At the leading edge of the blade, the liner walls are recurved to define a generally parallel-walled slot nozzle extending spanwise of the blade. Additional holes are placed along the outlet from this nozzle to flow additional air for entrainment by the jet emerging from the slot nozzle to improve cooling of the leading edge. Cooled air enters the liners through the blade stalk and is discharged preferably through the tip and trailing edge of the blade.
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Description  (OCR text may contain errors)

United States Patent [191 Aspinwall a Apr. 23, 1974 COOLEI) AIRFOIL [75] Inventor: Robert H. Aspinwall, Zionsville, Ind.

[73] Assignee: General Motors Corporation,-

' Detroit, Mich.

[22] Filed: Aug. 30, 1972 [21] App]. No.: 284,715

5 l Field of Search......416/92, 96, 97, 95, 415/] [56] References Cited UNITED STATES PATENTS 3,032,314 5/1962 David 416/96 3,635,587 1/1972 Giesman et al. 416/97 FOREIGN PATENTS OR APPLICATIONS 491,903 4/1953 Canada 416/96 1,222,565 2/1971 Great Britain fll6/97 Primary ExaminerEver ette A. Powell, Jr. Attorney, Agent, or Firm-Paul Fitzpatrick [57] ABSTRACT A hollow air-cooled turbine blade has a web extending from face to face of the blade to divide the interior of the blade into two spanwise-exte'nding chambers. A thin sheet metal liner is disposed in each chamber, the liner having perforations distributed over its surface and having projections to space it from the blade wall. The liner is flexible and may be folded substantially fiat for insertion into the end of the blade. At the leading edge of the blade, the liner walls are recurved to define a generally parallel-walled slot nozzle extending spanwise of the blade. Additional holes are placed along the outlet from this nozzle to flow additional air for entrainment by the jet emerging from the slot nozzle to improve cooling of the leading edge. Cooled air enters the liners through the blade stalk and is discharged preferably through the tip and trailing edge of the blade. i

5 Claims, 6 Drawing Figures PMENTEMR 23 m4 (1806; 275

sum 2 OF 2 IZO- WITH TURBULENCE PROMOTER LI. LU 8 8O CC A LL] u. 0 NO TURBULENCE g PROMOTER 1,- LU I l NOZZLE TO PLATE SPACING COOLED AIRFOIL DESCRIPTION My invention is directed to improved cooled turbine blades and the like. My invention is particularly directed to improved structures employing the principles of convection and impingement cooling. As used here,

the term convection cooling refers to the transfer of heat from the interior of a blade wall to a cooling medium flowing along the wall. Impingement cooling is a variation of convection cooling in which the cooling medium is directed as a sheet or jet toward the wall to be cooled, thereby improving the efficiency of the heat transfer or providingfor increased heat transfer in particular localities such, for example, as the leading edge 7 of a blade. The invention is particularly concerned with improvements of the cooling of the blade leading edge and with improved structure of a blade liner for this purpose. It is also concerned with a blade liner which may readily be installed in a previously completed turbine blade such as a cast blade, for instance.

Convection cooling of a blade wall, as distinguished from impingement cooling, is described in Zimmerman U.S. Pat. No. 2,859,011,'Nov. 4, 1958, and Emmerson et al, U.S. Pat. No. 3,446,480, May 27, 1969. Impingement cooling by air spouting from blade liners against the wall of a blade is described in Weise et al, U.S. Pat. No. 2,873,944, Feb. 17, 1959. A blade including a liner with special provisions for jetting air to theleading edge of the blade for impingement cooling is disclosed in Giesman etal, U.S. Pat. No. 3,635,587, Jan. 18, 1972. i

The general object of my invention is to provide improved structure to accomplish the sort of cooling described in these prior art patents and to provide a structure particularly suited to fabrication.

The nature of my invention and its advantages will be apparent to those skilled inthe art from the succeeding detailed description and accompanying drawings of the preferred embodiment of the invention.

FIG. 1 is a fragmentary sectional view of a turbine wheel with a blade'mounted thereon.

FIG. 2 is an axonometrio view of a turbine blade.

FIG. 3 is a transverse sectional view of the, blade taken on the plane indicated by the line 3-3 in FIG. 1.

FIG. 4 is a greatly enlarged view of the leading edge portion of FIG. 3.

FIG. 5 is a fragmentary axonometric view of the blade liner.

FIG. 6 is a graph illustrating certain parameters of impingement cooling.

Referring first to FIGS. 1 and 2, there is illustrated a,

turbine wheel 2 having a rim 3 on which are mounted a ring of fluid-reacting members or blading members 4, commonly known as blades. Each blade comprises a dovetail root 6, a stalk 7, a platform 8, and a blade proper or airfoil 10. The airfoil, as shown most clearly in FIG. 3, is hollow and has a leading edge at 11 a trailing edge at 12, a convex face 14, and a concave face lll spanwise of the blade through the platform and to the tip of the blade which is partially closed by a tip closure 20.

The stalk 7 is made up of two webs 22 diverging from the root to the platform which define between them an air space 23 having openings at the forward and rear faces of the stalk. The space within the stalk communicates'through the open inner end 24 of the blade with the chambers 18 and 19.

The blade root 6 is mounted in a suitably serrated slot in the wheel rim 3. The blade is retained and flow of fluid between the wheel rim and platforms is prevented by two cover plates or rings of cover plates 26 and 27. These cover plates may be unitary or segmented. The details are immaterial to the invention. Such plates are shown in U.S. Pat. No. 3,446,480 referred to above, and in White U.S. Pat. No. 3,034,298, May 15, 1962, for, example. Holes 28 in the plate 26 and 30 in the plate 27 provide for entry of cooling air or other mefrom whichthe fluid flows into the blade stalk and thus into the passages 18 and 19. The: fluid ultimately exhausts through openings 31 and 32 in the blade tip closure forward and rearward of the web 16, respectively. Also, preferably, the trailing edge of the blade is formed with outlets such as slots 34 for exhaust of cooling air at this point.

The structure asso far described may be considered part of the known state of the art. To indicate generally the scale of the drawings, the specific blade shown has a chord of about two inches.

To provide for air impingement and better flow of the cooling air along the interior of the surface of the blade wall, blade liners 35 and 36 are provided extending spanwise of the blade in chambers 18 and 19, respectively. These liners are open at the platform end of the blade and closed at the tip of the blade, and are made of very thin flexible heat resisting sheet metal, preferably about three to five thousandths inch thick. The liners are preferably spaced about twenty-five thousandths inch from the blade wall, the spacing being accomplished by embossed projections 38 extending outwardly from the liner. The liners have folds as indicated at139 in the liner 35 and correspondingly in the liner 36. With these folds, the liner may be flattened or collapsed as indicated generally by the broken line 40 so that the flattened liner may be inserted into the air space 23 in the blade stalk and'pushed on into the chamber 18 or 19. The liners may be made of such thin flexible material because they are not a structural element of the blade and are contained or supported by the wallsof the blade and the internal air pressure. After insertion, the liner may be expanded into contact with the blade wall by forcing a blast of fluid into the liner. Each liner has numerous small perforations distributed over its surface as indicated generally at 41 in FIGS. 2, 4, and 5. Air which flows from the'liner through these holes impinges against the inner surface of the blade wall and flows between the blade wall and liner to the outlets at 31, 32, and 34. These perforations may be about seven thousandths inch in diameter.

Considering now the structure of the liner 35 at the leading edge of the blade (FIGS. 4 and 5), the two sides or faces of the liner are recurved to define the side walls 42 of a slot nozzle 43. As shown most clearly in FIG. 5, these side walls are united by spacers 44 which are strips extending between the two walls 42 and brazed, welded, or otherwise fixed to them. The slot nozzle atits discharge'end thus terminates in generally cylindrical outwardly flaring wall sections 46. A row of holes 47 extends through each of these wall sections 46 in position to deliver cooling air into the sheet of air issuing from the slot nozzle 43.

The distance from slot 43 to the interior of the leading edge of the blade may be about fifty thousandths of an inch and the width of the slot preferably at least as great as one-eighth that distance, preferably about seven thousandths. The jet issuing from the slot nozzle has a greater penetrating power than that issuing from a simple hole such as 41 through the sheet metal. However, the distance from the holes 4l'to the blade wall is less.

With the flat jet issuing from the nozzle 43, this moving sheet of air tends to draw air from the holes 47 in the flaring part of the slot nozzle,'which air mixes with the flow from the slot nozzle and creates a greater mass flow, greater momentum, and greater turbulence at the point of impingement for greater removal of heat from the blade leadingedge.

FIG. 6 shows curves of heat transfer coefficient as a function of the ratio of nozzle to plate spacing to nozzle width, the upper curve indicating conditions with the turbulence promoter (additional air through 47). It will be noted that the heat transfer coefficient is significantly higher with the turbulence promoter, particularly as nozzle to plate spacing decreases below eight times the width of the nozzle.

The impingement tubes 35 and 36 may be fixed to the nozzle by welding, diffusion bonding, or a brazing operation at the area of the platform 8. Preferably, the margins of the liner are spread to lie under the platform and are electron beam welded to the platform at that point. Alternatively, the liners may be welded to the interior of the blade at its base. While it is considered less feasible, it should be noted that the spacing of the liner from the blade may be accomplished by protrusions from the inside of the blade rather than from the projections 38 on the liner.

As a matter of fabrication, it is also possible to diffusion bond the liner to the interior of the blade or airfoil and thereafter fix the blade'to the base or other mounting structure. In the case ofa turbine nozzle, which may be regarded as. a special case in which the blades are stationary, the attachment of the blade to the shrouds or other structure defining the flow path through the turbine may follow known practice. In this case, since there is no centrifugal force on the vane, retention of the liner is easier. If the liner is open at both ends, and the vane is supplied with air from both ends, there is not even any gas pressure tending to displace the liner.

prising, in combination, a hollow blade having leading and trailing edges and defining a spanwise-extending chamber, and a perforated blade liner disposed in the chamber, the end of the blade defining an opening for insertion of the liner, the liner conforming generally to the contour of the interior of the blade and being spaced from the blade wall, the liner including means defininga spanwise-extending slot nozzle for discharge of a cooling fluid directed at the leading edge of the blade and generally cylindrical diverging walls at the outlet of the nozzle, and defining perforations through the said diverging walls for flow of additional cooling fluid for entrainment by the flow through the slot nozzle.

2. An internally cooled turbine blading element comprising, in combination, a hollow blade having leading and trailing edges and a web disposed intermediate the said edges, so that the blade defines two spanwiseextending chambers, one at each side of the web, and a perforated blade liner disposed in each chamber, the end of the blade defining openings for insertion of the liners, each liner conforming generally to the contour of the interior of the blade and being spaced from the blade wall, the liner at the leading edge of the blade including means defining a spanwise-extending slot nozzle for discharge of a cooling fluid directed at the leading edge of the blade and generally cylindrical diverging walls at the outlet of the nozzle, and defining perforations through the said diverging walls for flow of additional cooling fluid for entrainment by the flow through the slot nozzle.

3. An internally cooled fluid-reacting member for a turbomachine comprising, in combination, wall means defining a blade with a central chamber having an opening at one end of the blade, a tubular perforated liner of thin flexible sheet metal disposed in the chamber, and spacer means maintaining a separation between the liner and the wall means over the major portion of the area of the liner, the liner being collapsible for insertion into the chamber through the said opening and being expandable by air pressure after such insertion to the extent allowed by the spacer means, the liner including means at the leading edge of the blade defining a spanwise-extending slot nozzle for a discharge of a cooling fluid directed at the leading edge of the blade and generally cylindrical diverging walls at the outlet of the nozzle, and defining perforations through the said diverging walls for flow of additional cooling fluid for entrainment by the flow through the slot nozzle. i I

4. An internally'cooled turbine blading element comprising, in combination, a root, a stalk, and a hollow blade extending from the stalk, the blade having leading and trailing edges and defining a spanwiseextending chamber, and a perforated blade liner disposed in the chamber, the stalk and the stalk end of the blade defining openings for insertion of the liner, the liner conforming generally to the contour of the interior of the blade and being spaced from the blade wall, the liner including means defining a spanwiseextending slot nozzle for discharge of a cooling fluid directed at the leading edge of the blade and generally cylindrical diverging walls at the outlet of the nozzle, and defining perforations through the said diverging walls for flow of additional cooling fluid for entrainment by the flow through the slot nozzle.

5. An internally cooled turbine blading element comprising, in combination, a root, a stalk, and a hollow blade extending from the stalk, the blade having leading and trailing edges and a web disposed intermediate the said edges, so that the blade defines two spanwiseextending chambers, one at each side of the web, and

6 rected at the leading edge of the blade and generally cylindrical diverging walls at the outlet of the nozzle, and defining perforations through the said diverging walls for flow of additional cooling fluid for entrainment by the flow through the slot nozzle.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3032314 *May 14, 1958May 1, 1962SnecmaMethod of and device for cooling the component elements of machines
US3635587 *Jun 2, 1970Jan 18, 1972Gen Motors CorpBlade cooling liner
CA491903A *Apr 7, 1953Rolls RoyceHollow blading for compressors and turbines
GB1222565A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3973874 *Sep 25, 1974Aug 10, 1976General Electric CompanyImpingement baffle collars
US4086021 *Jan 19, 1977Apr 25, 1978Stal-Laval Turbin AbCooled guide vane
US4111604 *Jul 12, 1976Sep 5, 1978General Electric CompanyBucket tip construction for open circuit liquid cooled turbines
US4162136 *Apr 1, 1975Jul 24, 1979Rolls-Royce LimitedCooled blade for a gas turbine engine
US4252501 *Nov 14, 1974Feb 24, 1981Rolls-Royce LimitedHollow cooled vane for a gas turbine engine
US4512715 *Jul 29, 1982Apr 23, 1985Electric Power Research Institute, Inc.Method and means for recapturing coolant in a gas turbine
US5003766 *May 8, 1989Apr 2, 1991Paul Marius AGas turbine engine
US5073083 *Mar 6, 1991Dec 17, 1991Societe Nationale D'etude De Construction De Moteurs D'aviationTurbine vane with internal cooling circuit
US5122033 *Nov 16, 1990Jun 16, 1992Paul Marius ATurbine blade unit
US5177954 *Jun 26, 1990Jan 12, 1993Paul Marius AGas turbine engine with cooled turbine blades
US5591002 *Aug 1, 1995Jan 7, 1997General Electric Co.Closed or open air cooling circuits for nozzle segments with wheelspace purge
US6193465Sep 28, 1998Feb 27, 2001General Electric CompanyTrapped insert turbine airfoil
US6439847 *Jan 31, 2001Aug 27, 2002Alstom (Switzerland) Ltd.Air-cooled turbine blade
US7025568Dec 22, 2003Apr 11, 2006Rolls-Royce PlcTurbomachine aerofoil
US7497655Aug 21, 2006Mar 3, 2009Florida Turbine Technologies, Inc.Turbine airfoil with near-wall impingement and vortex cooling
US8152468 *Mar 13, 2009Apr 10, 2012United Technologies CorporationDivoted airfoil baffle having aimed cooling holes
US8246306 *Apr 3, 2008Aug 21, 2012General Electric CompanyAirfoil for nozzle and a method of forming the machined contoured passage therein
US20090252603 *Apr 3, 2008Oct 8, 2009General Electric CompanyAirfoil for nozzle and a method of forming the machined contoured passage therein
EP0416542A1 *Sep 4, 1990Mar 13, 1991Hitachi, Ltd.Turbine blade
EP0974735A2 *Jul 14, 1999Jan 26, 2000General Electric CompanyDimpled impingement baffle
EP1113144A2 *Dec 18, 2000Jul 4, 2001ALSTOM (Schweiz) AGCooled fluid directing means for a turbomachine working at high temperatures
EP2228517A2 *Mar 15, 2010Sep 15, 2010United Technologies CorporationA cooled airfoil and an impingement baffle insert therefor
Classifications
U.S. Classification416/97.00R, 416/193.00A, 415/115
International ClassificationF01D5/18
Cooperative ClassificationF01D5/189
European ClassificationF01D5/18G2C