US3864058A

US3864058A - Cooled aerodynamic device

Info

Publication number: US3864058A
Application number: US329506A
Authority: US
Inventors: William C Womack
Original assignee: Garrett Corp
Current assignee: Garrett Corp
Priority date: 1973-02-05
Filing date: 1973-02-05
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04

Abstract

A cooled aerodynamic device having internal passages therein for the introduction of a cooling fluid. Separate orifices are provided for metering the cooling fluid flow to the opposing sides of the device individually.

Description

UnIted States Patent 1191 1111 3,864,058 Womack 1451 Feb. 4, 1975 COOLED AERODYNAMIC DEVICE 3,420,502 1/1967 Howald 415/115 [75 Inventor: winiam c. Womack, Scottsdale, 3,628,880 12/1971 3,656,863 4/1972 [73] Ass1gnee. 'flslllllegjsrrgilgorporation, Los 3,706,508 12/1972 3 3,767,322 10/1973 [22] Wed: 1973 FOREIGN PATENTS OR APPLICATIONS pp No.: 329,506 833,770 4/1960 @1661 Britain 416/96 A 200,185 1/1955 Australia 416/97 52 US. Cl. 416 7, 415 isli Int. Cl. F01d EmmmPEverem [58] Field 61 Search ..416/9 6 92 97 95' PufferAlbertJ- [561 References Cited [57] ABSTRACT UNITED STATES PATENTS A cooled aerodynamic device having internal passages 2,648,520 8/1953 Schmifl. 416/97 therein for the introduction of a fluid- Sepa- 2 7 3 427 9 195 rate orifices are provided for metering the cooling 2,847,185 8/1958 fluid flow to the opposing sides of the device individu- 2,931,623 4/1960 ally. 2,991,973 7/1961 3,240,463 3/1966 11 Claims, 4 Drawing Figures 1 COOLED AERODYNAMIC DEVICE BACKGROUND OF THE INVENTION This invention relates to aerodynamic nozzles for directing the flow of a fluid into a rotating element such as a compressor or turbine wheel. In particular this invention relates to such nozzles having internal passages for supplying cooling air to the nozzle to prevent overheating when exposed to high temperature gases.

Aerodynamic nozzles having an airfoil shape are subjected to uneven aerodynamic heating because of the difference in the velocity of the fluid flowing over the suction surface and the pressure surface. Because of the aerodynamic shape of the nozzle, gas passing over the suction surface has a substantially higher velocity than gas passing along the opposite or pressure surface of the nozzle. The velocity of gas on the suction surface may be many times that of the velocity on the pressure surface. The rate of convective heat transfer depends in large part upon the gas velocity. Thus, because of the difference in velocity of the nozzle surfaces, the heating rate on the surfaces will be substantially different. This temperature gradient across the nozzle section produces undesirable thermal stresses which may lead to premature failure of the part. Additionally, the most efficient nozzle design is one having a thin trailing edge. The combination of uneven heating across the nozzle section and the variable crosssectional area of the nozzle create a substantial thermal stress problem.

In the prior art cooled nozzle designs, there have been provided cooling passages within the nozzle, however, such nozzles are difficult to manufacture because precision machining or casting of internal passages is required. Another means of providing cooling in a nozzle blade is to provide a hollow aerodynamic-shaped shell and insert a second body within the shell and spaced apart from the shell. The space between the shell and the insert is then used for providing passage for the cooling air. However, here again precise machining or casting is required to provide nonuniform wall spacing required for equal surface cooling. When a single source of cooling fluid is used, the insert shape is critical and requires precise machining. In addition, in some cases the spacing between the insert and the shell becomes so small that the effect of standard machining tolerances are significant in the success or failure of the cooling scheme. An additional problem is created when trailing edge discharge cooling slots are utilized to control coolant flow rates. Generally, manufacturing limitations of slot widths afford little pressure drop throughout the slot length and thus coolant flow may be drastically reduced or possibly reversed due to fluctuations in the hot gas mainstream static pressure at the slot exit.

This invention overcomes these disadvantages by providing a separately machinable insert for insertion within the hollow aerodynamic shell in which all the clearance surfaces are external surfaces and are more easily machined or cast. Further, two separate supply ports are provided for the cooling fluid. One port is in communication with the cooling passage for the suction surface and the other port communicates with the passages for cooling the pressure surface. Each port can be separately metered by an appropriate orifice or other means to provide the required flow for the convective heating anticipated for each individual surface. These two streams are combined downstream of the coolingfluid inlet and are discharged through a slot at the trailing edge of the nozzle. The separate supplies for the pressure and suction surfaces provide variable cooling across the leading edge and center of the nozzle and discharging the cooling fluid on the pressure surface at the thin trailing edge of the airfoil through a cooling slot cut along the pressure surface thereby providing for cooling of the thin trailing edge.

Thus it can be seen that there is provided by this invention a cooled aerodynamic nozzle which provides nonuniform cooling commensurate with the nonuniform heating anticipated and further provides for effectively cooling a thin trailing edge of the airfoil. These advantages are provided in a design which is readily producible at a reasonable cost in large quantities.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of the assembled nozzle.

FIG. 2 is an exploded view of the nozzle showing the various component parts.

FIG. 3 is a partial section of the nozzle.

FIG. 4 is a sectional view of the nozzle taken along line 4-4 of FIG. 3

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, there is shown an assembled nozzle shown generally at having an aerodynamic shape providing a suction surface 12 and a pressure surface 14. The airfoil shape terminates in a thin trailing edge shown at 16. In FIG. 2 there is shown the nozzle body member 18 having a cavity 20 formed in its interior. There is provided a cooling slot 22 along the trailing edge of the pressure surface and in communication with the cavity 20. An insert member 23 is provided for insertioninto the cavity 20. The outside surface of the insert is depressed from the outline to form two cavities shown at 24 and 26. These cavities are separated by a wall member 27 but are connected on the opposite'side of the insert. There are provided two cooling ducts shown generally at 30 and 32. These ducts are in communication with the

cavities

26 and 24 respectively and connected to a source of cooling fluid (not shown). Each tube is provided with a threaded portion 34 for attaching

metering caps

36 and 38 to the tubes. Each of the metering caps is provided with an orifice shown at 40 and 42 of a predetermined size for metering the flow of cooling gas into the tubes.

There is shown in FIGS. 3 and 4 by means of sectional views, the paths provided for the cooling gases. In FIG. 3 the cooling gas enters tube 30 and is metered through the metering cap orifice 40 in the cap 36. The gas then flows through cavity 26 for cooling the suction surface of the nozzle. At the opposite end the second tube 32 is provided with a metering cap 38 having a different sized orifice 42 for metering flow into cavity 24. The cooling gas flows through the metering orifice 42 into cavity 24 for cooling the pressure surface of the nozzle. In FIG. 4 there is shown the means by which the flow from the separate metering orifices is combined toward the trailing edge of the nozzle. Thus gas entering nozzle 40 passes through chamber 26 along the suction surface and into a mixing area 44. Cooling gas entering orifice 42 is directed into chamber 24 separated from chamber 26 by wall member 27. The gas from orifice 42 flows along the inside of the pressure surface and is mixed with the gas from chamber 26 at the mixing area 44. Downstream of this mixing area there is provided a passage 46 which is in communication with cooling slot 22 cut in the trailing edge of the pressure surface. The cooling air from the mixing area 44 passes through opening 46 and is discharged through slot 22 and flows on the pressure surface of the thin trailing edge providing cooling thereto.

Thus it can be seen that there is provided herein an improved cooled aerodynamic nozzle which provides differential cooling to compensate for differential external heating to provide uniform cooling throughout the nozzle section. Obviously many modifications and variations of the present invention are possible in light of the above teaching. it is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

lt is claimed:

1. A fluid cooled aerodynamic device comprising:

a fluid impervious shell member of aerodynamic shape having leading and trailing edges and having a cavity therein extending along its entire span with an exit opening cummunicating between said cavity and the'ambient atmosphere;

a body member inserted in the cavity of said shell member said body being spaced apart from said shell member at predetermined points to form a plurality of chordwise cooling fluid passages therebetween in communication with the exit opening of said shell member and having openings communicating between each of said passages and a source of cooling fluid said body member forming closure means for the ends of said cavity; and

metering means for metering cooling fluid flow from said source into each of said cooling fluid passages.

2. A fluid cooled aerodynamic device according to claim 1 wherein the exit opening in said shell member in communication with the ambient atmosphere is at the trailing edge of said shell member.

3. The fluid cooled aerodynamic device of claim 2 wherein the exit opening is a slot-shaped opening.

4. A fluid cooled aerodynamic blade comprising:

a shell member of aerodynamic shape having a suction surface and a pressure surface and leading and trailing edges, said shell having a cavity therein and an opening in communication with said cavity and the ambient atmosphere;

a body member formed generally in the shape of said cavity and inserted therein, said body member being spaced apart from the inner wall of said cavity at predetermined points to form at least one cooling fluid passage therebetween said passage being in communication with the opening of said shell member and extending across the chord of the blade to provide for flow of cooling fluid from the leading to the trailing edge;

conduit means connecting said cooling fluid passage with a source of cooling fluid; and

metering means for controlling cooling fluid flow in said conduit.

5. A fluid cooled aerodynamic blade according to claim 4 wherein said body member includes a wall member, said wall member forming a plurality of cooling fluid passages, each of said passages being connected to separate conduit means.

6. A fluid cooled aerodynamic blade according to claim 5 wherein said body member forms two cooling fluid passages, one of said passages being in fluid contact with the surface of said cavity nearest the suction surface of said shell member and the other of said passages in fluid contact with the surface of said cavity nearest the pressure surface.

7. A fluid cooled aerodynamic blade comprising:

a shell member of aerodynamic shape having first and second aerodynamic surfaces forming a leading and trailing edge, said shell having an opening approximating the exterior aerodynamic shape and extending along the entire span of the blade and connected by a fluid passage to a fluid exit port;

an insert member shaped generally in the form of the span-wise opening in the shell member at its top and bottom surfaces, and having relieved portions intermediate said top and bottom surfaces, said relieved portions forming a plurality of chordwise cooling passages between the internal surface of said shell member and said insert, said top and bottom surfaces forming closures to the ends of the span-wise passage;

a plurality of conduit means attached to said insert member, each of said conduit means connecting one of said cooling passages with a source of cooling fluid; and

metering means attached to each of said conduits between the source of cooling fluid and its respective cooling passage for independently metering flow of cooling fluid to each passage.

8. The fluid cooled aerodynamic blade of claim 7 wherein first and second separate cooling passages are formed, said passages being adjacent the first and second aerodynamic surfaces of said shell member respectively, said passages being connected at a common point to the exit port of said shell member.

9. The fluid cooled aerodynamic blade of claim 8 wherein said exit port comprises a slot-like opening formed one one of said aerodynamic surfaces at the trailing edge thereof.

10. The fluid cooled aerodynamic device of claim 1 wherein said body member forms two chordwise passages, one of said passages being formed along the chord of the suction surface and the other passage being formed along the chord of the pressure surface.

11. The fluid cooled aerodynamic device of claim 9 wherein one of said conduit means is connected at the top of the surface of said insert member and the other of said conduits is connected to the bottom surface of said insert member and said metering means comprises an orifice plate assembled in each of said conduit means.

Claims

1. A fluid cooled aerodynamic device comprising: a fluid impervious shell member of aerodynamic shape having leading and trailing edges and having a cavity therein extending along its entire span with an exit opening cummunicating between said cavity and the ambient atmosphere; a body member inserted in the cavity of said shell member said body being spaced apart from said shell member at predetermined points to form a plurality of chordwise cooling fluid passages therebetween in communication with the exit opening of said shell member and having openings communicating between each of said passages and a source of cooling fluid said body member forming closure means for the ends of said cavity; and metering means for metering cooling fluid flow from said source into each of said cooling fluid passages.

4. A fluid cooled aerodynamic blade comprising: a shell member of aerodynamic shape having a suction surface and a pressure surface and leading and trailing edges, said shell having a cavity therein and an opening in communication with said cavity and the ambient atmosphere; a body member formed generally in the shape of said cavity and inserted therein, said body member being spaced apart from the inner wall of said cavity at predetermined points to form at least one cooling fluid passage therebetween said passage being in communication with the opening of said shell member and extending across the chord of the blade to provide for flow of cooling fluid from the leading to the trailing edge; conduit means connecting said cooling fluid passage with a source of cooling fluid; and metering means for controlling cooling fluid flow in said conduit.

7. A fluid cooled aerodynamic blade comprising: a shell member of aerodynamic shape having first and second aerodynamic surfaces forming a leading and trailing edge, said shell having an opening approximating the exterior aerodynamic shape and extending along the entire span of the blade and connected by a fluid passage to a fluid exit port; an insert member shaped generally in the form of the span-wise opening in the shell member at its top and bottom surfaces, and having relieved portions intermeDiate said top and bottom surfaces, said relieved portions forming a plurality of chordwise cooling passages between the internal surface of said shell member and said insert, said top and bottom surfaces forming closures to the ends of the span-wise passage; a plurality of conduit means attached to said insert member, each of said conduit means connecting one of said cooling passages with a source of cooling fluid; and metering means attached to each of said conduits between the source of cooling fluid and its respective cooling passage for independently metering flow of cooling fluid to each passage.