WO2010002294A1

WO2010002294A1 - A vane for a gas turbine component, a gas turbine component and a gas turbine engine

Info

Publication number: WO2010002294A1
Application number: PCT/SE2008/000427
Authority: WO
Inventors: Linda STRÖM; Jonas Larsson; Fredrik Wallin
Original assignee: Volvo Aero Corporation
Priority date: 2008-07-04
Filing date: 2008-07-04
Publication date: 2010-01-07

Abstract

The invention relates to a vane (16) for a gas turbine component, wherein the vane is configured for being attached to at least one end wall (32,33) defining a gas path in the component. The vane has a first extension direction between a leading edge and a trailing edge and a second extension direction (43) between an attachment position (45) to said end wall (32) and an opposite end (47). The trace of the vane (16) in a cross section perpendicular to the first extension direction (37) extends with a continuously increasing distance in a direction from a centre line (51) of the vane in said second extension direction (51) from a mid span (35) of the vane towards said attachment position (45) and/or end (47) on at least one of the sides of the vane in said cross section.

Description

A vane for a gas turbine component, a gas turbine component and a gas turbine engine

TECHNICAL FIELD

The present invention relates to a vane for a gas turbine component, wherein the vane is configured for being attached to at least one end wall defining a gas path in the component, wherein the vane has a first extension direction between a leading edge and a trailing edge and a second extension direction between an attachment position to said end wall and an opposite end.

The term "vane" comprises an aerodynamic element and/or a structural element (also called "strut") , which is configured for extension in a radial direction in a static gas turbine component, i.e in a component fixed in position in relation to the gas turbine engine. In stators, the vane is normally attached to both an inner wall and an outer wall . The aerodynamic element performs aerodynamic work, is subjected to aerodynamic loads and/or modifies the flow field.

The term "strut" refers to a structural vane, i.e a vane carrying a load in operation. Struts are often hollow in order to house service components such as means for the intake and outtake of oil and/or air, for housing instruments, such as electrical and metallic cables for transfer of information concerning measured pressure and/or temperature etc. The struts normally have a symmetric airfoil shape in cross section in order to effect the gas flow as little as possible. The servicing requirement usually governs the number of struts required.

The term "vane" further comprises a radial element (also called "blade") when it is applied in a gas turbine component configured for rotation in the gas turbine engine. Blades are attached to rotors via the inner wall through a base, thereby rotating with the rotor. Thus, the blade may have a free end (blade tip) .

The invention is further directed to a gas turbine component comprising such a vane. The invention will below be described for an intermediate compressor component (also called structure or frame) , which is positioned between two compressor stages (for example the low pressure compressor and the high pressure compressor) . The intermediate compressor structure is adapted to transfer loads and form support for bearings. It should be regarded as a non-limiting example application.

The invention is further directed to a gas turbine engine, and especially to an aircraft engine, comprising the component. Thus, the invention is especially directed to a jet engine.

Jet engine is meant to include various types of engines, which admit air at relatively low velocity, heat it by combustion and shoot it out at a much higher velocity. Accommodated within the term jet engine are, for example, turbojet- engines, turbofan and turboprop engines. The invention will below be described for a turbofan engine, but may of course also be used for other engine types. BACKGROUND OF THE INVENTION

The flow field in a gas channel in the gas turbine engine is modified by the presence of the vane. The vane can be aerodynamically shaped to either carry aerodynamic load (impose turning) or to be unloaded. In either case the velocity field and static pressure field on the vane are varying with distance along the flow direction. The exterior of the vane generally are referred to as the flow path surfaces. The flow path surfaces include a pressure side on a concave side of the airfoil extending from the leading edge to the trailing edge, and a convex side, opposite the concave side .

In a gas channel with constant area, the flow around the convex shaped side of the vane first accelerates to the position of maximum thickness, and then decelerates towards the trailing edge. In the decelerating region the flow is sensitive to flow separation and end wall losses. The intersection between vane and end wall is traditionally close to perpendicular (there may be a fillet radius forming a smooth contour between the vane and the end wall) . In those regions separation growth occurs as corner separations.

Total pressure losses occur in gas turbine parts by frictional losses at all flow surfaces (end walls and vanes) . Additional total pressure losses result from secondary circulations. Secondary circulations occur due to interactions of end walls with main gas flow and obstacles/features in particular those that are performing aerodynamic work or are subjected to aerodynamic loads. In low aspect ratio gas turbine parts the influences of end wall related losses are especially large.

SUMMARY OF THE INVENTION

An object of the invention is to achieve a vane for a gas turbine component with an improved aerodynamic function.

This object is achieved in a vane according to claim 1. Thus, it is achieved in that the trace of the vane in a cross section perpendicular to the first extension direction extends with a continuously increasing distance in a direction from a centre line of the vane in said second extension direction from a mid span of the vane towards said attachment position and/or end on at least one of the sides of the vane in said cross section.

Thus, the vane is thicker at the end wall (and/or the end) than in the middle of the gas path, i.e. increasing thickness close to the end wall (and/or the end) . Thus, looking from the mid span (the middle of the gas path) , the vane can have increasing thickness radially outwards or radially inwards or both radially inwards and outwards .

This solution creates conditions for use in collocation with engine mount recesses to account for an additional blockage by the engine mount recesses and/or to control separation at bump and vane intersection (corner separations) . Further, this solution creates conditions for suppressing corner separations at outer end wall-vane intersection and/or at inner end wall-vane intersections.

Further, this solution creates conditions for allowing a more local diffusion by the vane and/or allowing a more global diffusion in the gas turbine component.

Thus, the solution creates conditions for an aerodynaitiically improved component. More specifically the vane design is adapted to modify the local flow field in the vicinity of the vane and the end wall(s). This in turn creates conditions for a higher velocity and lower pressure, a modified radial pressure gradient and a transport from mid span region toward end wall (s) .

Further, the solution creates conditions for a reduction of end-wall related performance losses. Especially aerodynamic performance and efficiency may be improved, wherein specific fuel consumption (sfc) may be lowered, flow separations may be reduced and controlled.

Further, the solution creates conditions for performance benefits, robust operation etc.

Further, the solution creates conditions for less interference and interaction with neighboring components during operation.

Further, the solution creates conditions for less wear and tear (reduction in vibration, forced-response etc.). Especially, vibration in the component is reduced.

Further, the solution creates conditions for allowing shorter and more aggressive ducts, which leads to weight savings.

Further, the solution allows fewer and in average thicker struts, which leads to weight savings.

Further, the solution allows for polygonal outer case (which is a structural need) . Further, the solution allows for engine mount recesses (which is a structural need) .

According to a preferred embodiment, the trace of the vane in said cross section has a curved shape from the mid span of the vane towards at least one of said attachment position and said end. Thus, the flow guiding surface of the vane has a concave shape facing the gas path. This embodiment creates conditions for a smooth contour between the vane and the end wall and also across the mid span towards the opposite end of the vane .

According to a further preferred embodiment, the trace of the vane in said cross section extends with a continuously increasing distance in the direction from the centre line of the vane in said second extension direction from the mid span towards said attachment position. Thus, the trace of the vane extends with a continuously increasing distance in the direction from the centre line of the vane towards the end wall attachment position. This embodiment creates conditions for a smooth contour between the vane and the end wall, thereby improving aerodynamic functionality.

According to a further preferred embodiment, the trace of the vane in said cross section extends with a continuously increasing distance in the direction from the centre line of the vane in said second extension direction from a mid span of the vane towards at least one of said attachment position and said end on both sides of the vane in said cross section. Thus, the distance from the centre line of the vane increases in opposite directions from the centre line in said cross section. Preferably, the shape of the vane is symmetrical. In other words, the trace of the vane is mirrored in said centre line. This embodiment creates conditions for a similar flow field in the gas passages on opposite sides of the vane during operation of the gas turbine engine, wherein operation is improved.

This object is also achieved in a vane according to claim 8. Thus, it is achieved in a vane for a gas turbine component, wherein the vane is configured for being attached to an end wall defining a gas path in the component, wherein the vane has a first extension direction between a leading edge and a trailing edge characterized in that the trace of the vane in a cross section perpendicular to the first extension direction has the shape of a sandglass. The term sandglass relates to a shape wherein both flow guiding surfaces of the vane are concave facing the gas flow. Further, the contours of the flow guiding surfaces of the vane are preferably symmetrical with regard to a centre line of the vane. Other advantageous features and functions of various embodiments of the invention are set forth in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained below, with reference to the embodiment shown on the appended drawings, wherein FIG 1 is a schematic side view of an aircraft engine cut along a plane in parallel with the rotational axis of the engine,

FIG 2 is a schematic, perspective view of a compressor intermediate component from figure 1, FIG 3 is a cross sectional view of the component in figure 2, FIG 4 is a cross sectional view of the component in figure 3, FIG 5 is an enlarged cross sectional view of one of the vanes in the component shown in figure 3, and FIG β is a schematic, cross sectional view of a further embodiment of the component.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE

INVENTION

The invention will below be described for a two-shaft turbofan aircraft engine 1, which in figure 1 is circumscribed about an engine longitudinal central axis 2. The engine 1 comprises an outer casing or nacelle 3, an- inner casing 4 (rotor) and an intermediate casing 5 which is concentric to the first two casings and divides the gap between them into an inner primary gas channel 6 for the compression of air and a secondary channel 7 in which the engine bypass air flows. Thus, each of the gas channels 6,7 is annular in a cross section perpendicular to the engine longitudinal central axis 2.

The engine 1 comprises a fan 8 which receives ambient air 9, a booster or low pressure compressor (LPC) 10 and a high pressure compressor (HPC) 11 arranged in the primary gas channel 6, a combustor 12 which mixes fuel with the air pressurized by the high pressure compressor

11 for generating combustion gases which flow downstream through a high pressure turbine (HPT) 13 and a low pressure turbine (LPT) 14 from which the combustion gases are discharged from the engine.

A high pressure shaft joins the high pressure turbine 13 to the high pressure compressor 11 to substantially form a high pressure rotor. A low pressure shaft joins the low pressure turbine 14 to the low pressure compressor

10 to substantially form a low pressure rotor. The low pressure shaft is at least in part rotatably disposed co-axially with and radially inwardly of the high pressure rotor.

The casings 4,5 are supported by a component, 15, see figure 2, which connect the housings by a plurality of circumferentially spaced radial vanes, or arms 16,17. These vanes are generally known as struts. The struts are designed for transmission of loads in the engine. Further, the struts may be hollow (not shown) in order to house service components such as means for the intake and outtake of oil and/or air, for housing instruments, such as electrical and metallic cables for transfer of information concerning measured pressure and/or temperature, a drive shaft for a start engine etc. The struts can also be used to conduct a coolant. The component 15 connecting the intermediate casing 5 and the inner casing 4 can for example be applied as an Intermediate Case (IMC) , Intermediate Compressor Case (ICC) or Fan Hub Frame (FHF) . The component 15 is designed for guiding the gas flow from the low pressure compressor section 10 radially inwards toward the high pressure compressor section inlet.

Figure 2 shows a schematic, perspective view of the relevant part of the intermediate component 15 from figure 1. The component 15 comprises two end walls 32, 33, in the form of an inner wall 32 and an outer wall 33 defining a gas path therebetween. The plurality of circumferentially spaced vanes 16,17 are rigidly connected to both the inner ring 32 and to the outer ring 33 forming a load-carrying structure. Although not explicitly shown in figure 2, the vane 16 preferably has an airfoil shape with a rounded leading edge facing the incoming gas flow.

Figure 3 shows a cross sectional view along the cut A-A of the component in figure 2. A dotted line 35 indicates a mid span of the vanes 16,17. The mid span of the vanes 16,17 forms a central position between an attachment position 45 to the inner wall 32 and an attachment position 47 to the outer wall 33, see also figure 5. Thus, the mid span of the vanes 16,17 coincides with a central line between the inner wall 32 and the outer wall 33. More specifically, the mid span 35 defines a position where the vane has its smallest thickness.

Figure 4 shows a single vane 16 in a cross sectional view along the cut B-B of the vane 16 in figure 3. The vane 16 has a first extension direction, which is indicated by the arrow 37, between a leading edge 39 and a trailing edge 41.

Figure 5 shows an enlarged view of the vane 16 in figure 3. The vane 16 has a second extension direction, which is indicated by the arrow 43, between the attachment position 45 to the inner wall 32 and the attachment position 47 to the outer wall 33. The second extension direction 43 is in this embodiment perpendicular relative to the first extension direction 37.

More specifically, figure 5 shows a section of the component 15. The section is divided in four quadrants A, B, C and D. Quadrants A and C define a first side of the vane (in a circumferential direction of the component) and quadrants B and D define a second side of the vane, which is opposite the first side.

The design of the vane 16 will now be described with regard to quadrant A. The trace 49 of the vane 16 in quadrant A extends with a continuously increasing distance in a direction from a centre line 51 of the vane 16 in said second extension direction 43 from the mid span 35 of the vane towards the outer wall attachment position 47. More specifically, the trace 49 of the vane has a curved, concave shape from the mid span 35 of the vane towards said outer wall attachment position 47. The centre line 51 of the vane is straight.

Turning now to quadrant B. The trace 53 of the vane 16 in quadrant B extends with a continuously increasing distance in a direction from the centre line 51 of the vane 16 in said second extension direction 43 from the mid span 35 of the vane towards the outer wall attachment position 47. More specifically, the trace 53 of the vane has a curved, concave shape from the mid span 35 of the vane towards said outer wall attachment position 47. Thus, the shape of the trace 53 of the vane in quadrant B is mirrored with regard to the shape of the trace 49 of the vane in quadrant A.

Turning now to quadrant C. The trace 55 of the vane 16 in quadrant C extends with a continuously increasing distance in a direction from the centre line 51 of the vane 16 in said second extension direction 43 from the mid span 35 of the vane towards the inner wall attachment position 45. More specifically, the trace 55 of the vane has a curved, concave shape from the mid span 35 of the vane towards said inner wall attachment position 45.

Turning now to quadrant D. The trace 57 of the vane 16 in quadrant D extends with a continuously increasing distance in a direction from the centre line 51 of the vane 16 in said second extension direction 43 from the mid span 35 of the vane towards the inner wall attachment position 45. More specifically, the trace 57 of the vane has a curved, concave shape from the mid span 35 of the vane towards said inner wall attachment position 45. Thus, the shape of the trace 57 of the vane in quadrant D is mirrored with regard to the shape of the trace 55 of the vane in quadrant C.

Thus, the first side of the vane (which is defined by quadrants A and C) is mirrored with regard to the second side of the vane (which is defined by quadrants

B and D) .

The trace 49,55 on the first side of the vane 16 forms a continuous, concave shape from the inner wall 32 to the outer wall 33. Further, the trace 53,57 on the second side of the vane 16 forms .a continuous, concave shape from the inner wall 32 to the outer wall 33.

More specifically, the trace of the vane 16 in a cross section perpendicular to the first extension direction 37 has the shape of a sandglass.

Figure 6 shows a further embodiment of a gas turbine component 115 in a cross sectional view. The component 115 comprises at least an inner wall 132 and an outer wall 133 de.fining a gas path and a plurality of circumferentially spaced vanes 116,117 attached to the walls. The component 115 comprises at least one engine mount recess 601 associated to the outer wall 133. More specifically, the component comprises three engine mount recesses. One vane 116 is associated to each engine mount recess. More specifically, the vane 116 is connected to a wall portion 602 defining the recess 601. At least one of the three vanes 116 connected to the recess wall 602 (and preferably all three vanes) has the shape defined above for the vane 16. In addition, At least one of the further vanes 117 (and preferably all five remaining vanes) are formed by a conventional, straight hollow vane for housing an element such as a tube for oil etc.

Another term for the term "trace" used hereinabove is "contour". The invention is not in any way limited to the above described embodiments, instead a number of alternatives and modifications are possible without departing from the scope of the following claims.

The invention is of course not limited to application in a two-shaft engine, but may very well be applied in other engine types, such as a three shaft engine.

The invention is not limited to application in an intermediate compressor structure but may for example be applied in a compressor rear structures, turbine intermediate and rear structure.

The invention is not limited to that the trace of the vane has the shape defined above in all four quadrants . Instead, the shape may differ between the different sides of the vane (facing adjacent gas channels) . Further, the shape may differ on opposite sides of the mid span 35. For example, at least a part of one of the sides may be straight.

Further, the invention is not limited to static components, i.e components which are fixed relative to the gas turbine engine. Instead, the invention may be applied to a rotor.

Further, the invention is not limited to a component, in which the vane is attached to both the inner wall and the outer wall. Instead, the vane may be attached to a single end wall, such as the inner wall. Thus, the vane may have a free end opposite the attached end. This design is especially applicable for a rotor, see above.

Claims

1. A vane (16,116) for a gas turbine component (15,115), wherein the vane is configured for being attached to at least one end wall (32,132,33,133) defining a gas path in the component, wherein the vane has a first extension direction (37) between a leading edge (39) and a trailing edge (41) and a second extension direction (43) between an attachment position (45) to said end wall (32,132) and an opposite end (47) characterized in that the trace of the vane (16,116) in a cross section perpendicular to the first extension direction (37) extends with a continuously increasing distance in a direction from a centre line (51) of the vane in said second extension direction (51) from a mid span (35) of the vane towards said attachment position (45) and/or end (47) on at least one of the sides of the vane in said cross section.

2. A vane according to claim 1, characterized in that the trace of the vane (16,116) in said cross section has a curved shape from the mid span (35) of the vane towards at least one of said attachment position (45) and said end (47) .

3. A vane according to claim 1 or 2, characterized in that the trace of the vane (16,116) in said cross section extends with a continuously increasing distance in the direction from the centre line (51) of the vane in said second extension direction (43) from the mid span (35) towards said attachment position (45) .

4. A vane according to any preceding claim, characterized in that the trace of the vane (16,116) in said cross section extends with a continuously increasing distance in the direction from the centre line (51) of the vane in said second extension direction (43) from the mid span (35) towards said end (47) .

5. A vane according to any preceding claim, characterized in that the trace of the vane (16,116) in said cross section extends with a continuously increasing distance in the direction from the centre line (51) of the vane (16,116) in said second extension direction (43) from a mid span (35) of the vane towards at least one of said attachment position (45) and said end (47) on both sides of the vane in said cross section.

6. A vane according to any preceding claim, characterized in that the end wall forms an inner wall

(32,132) and/or an outer wall (33,133) with regard to the gas path.

7. A vane according to claim 6, characterized in that the attachment position (45) is configured for attachment to said inner wall (32,132) and the end forms an attachment position (47) to said outer wall (33,133) .

8. A vane (16,116) for a gas turbine component

(15,115), wherein the vane is configured for being attached to an end wall (32,132,33,133) defining a gas path in the component, wherein the vane has a first extension direction (37) between a leading edge (39) and a trailing edge (41) characterized in that the trace of the vane (16,116) in a cross section perpendicular to the first extension direction (37) has the shape of a sandglass.

9. A vane according to any preceding claim, characterized in that the vane (16,116) is configured for performing aerodynamic work.

10. A vane according to any preceding claim, characterized in that the vane (16,116) is configured for carrying structural loads.

11. A gas turbine component (15,115) comprising at least one end wall (32,132,33,133) defining a gas path and a plurality of circumferentially spaced vanes (16,116,17,117) attached to said at least one end wall, characterized in that at least one of the vanes (16,116) is formed by a vane according to any preceding claim.

12. A gas turbine component (15,115) according to claim 11, characterized in that the component comprises an inner wall (32,132) and an outer wall (33,133) defining a gas path therebetween, wherein said plurality of circumferentially spaced vanes (16,116,17,117) extend between the inner wall and the outer wall.

13. A gas turbine component (115) according to claim 11 or 12, characterized in that the component comprises at least one engine mount recess (601) associated to the outer wall (133) and that the vane (116) is connected to a wall portion (602) defining the recess (601) .

14. A gas turbine engine (1) characterized in that it comprises a gas turbine component (15,115) according to any one of claims 11-13.

15. A gas turbine engine (1) according to claim 14, characterized in that the gas turbine component (15,115) is positioned between two gas turbine engine stages (10, 11; 13, 14) .

16. A gas turbine engine (1) according to claim 14, characterized in that the gas turbine component (15,115) is positioned downstream a turbine engine stage (13,14) .