GAS TURBINE ENGINE SHEET METAL VANE

Abstract

A gas turbine engine stator vane has a sheet metal body with a pressure surface and a suction surface extending chordwise from a leading edge to a trailing edge. The sheet metal body has opposed pressure and suction side trailing end portions that meet at a joint upstream from the trailing edge of the airfoil. The pressure and suction surfaces of the sheet metal body are parallel to one another between the joint and the trailing edge, thereby forming a straight non-tapering trailing edge section from the joint to the trailing edge of the airfoil.

Description

TECHNICAL FIELD

The application relates generally to gas turbine engines and, more particularly, to gas turbine engine vanes.

BACKGROUND OF THE ART

Sheet metal vanes usually have an airfoil tapering from a rounded leading edge to a sharp trailing edge. The airfoil is typically formed from a suction side sheet and a pressure side sheet welded together at the airfoil leading and trailing edges by butt welds. The butt welds need to be ground to the parent sheet material and polished to obtain smooth airfoil leading and trailing edges. Accordingly, extra manufacturing operations must be performed in order to obtain adequate aerodynamic surface finishes. Furthermore, the grinding and polishing operations may compromise the quality of the butt welds. Finally, the presence of a butt weld at the trailing edge of the airfoil does not allow altering the trailing edge section of the airfoil such as to provide for vane flow adjustment area.

SUMMARY

In one aspect, there is provided a gas turbine engine stator vane comprising a hollow airfoil having a sheet metal body with a pressure surface and a suction surface extending chordwise from a leading edge to a trailing edge, the sheet metal body having opposed pressure and suction side trailing end portions that meet at a joint upstream from the trailing edge of the airfoil, the pressure and suction surfaces of the sheet metal body being substantially parallel to one another between said joint and said trailing edge, thereby forming a straight, non-tapering trailing edge section from the joint to the trailing edge of the airfoil.

In a second aspect, there is provided a gas turbine engine stator vane comprising a pressure side sheet and a suction side sheet joined together to define an airfoil having a leading edge and a trailing edge, said pressure side sheet and said suction side sheet having a trailing end joint which is spaced chordwise from the trailing edge of the airfoil, at least one of the pressure and suction side sheets extending chordwise beyond said trailing edge joint and defining a straight trailing edge section having parallel suction and pressure surfaces.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures, in which:

FIG. 1 is a schematic cross-sectional view of a turbofan gas turbine engine;

FIG. 2a is a cross-sectional view of an embodiment of a stator vane suited for use in the engine shown in FIG. 1;

FIG. 2b is an enlarged cross-sectional view of a trailing edge section of the stator vane shown in FIG. 2a;

FIG. 3a is a cross-sectional view of another embodiment of the stator vane; and

FIG. 3b is an enlarged cross-sectional view of a trailing edge section of the stator vane shown in FIG. 3a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a turbofan gas turbine engine 10 of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan 12 through which ambient air is propelled, a multistage compressor 14 for pressurizing the air, a combustor 16 in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section 18 for extracting energy from the combustion gases.

As well know in the art, the compressor and the turbine sections 14 and 18 are provided with respective arrays of stator vanes located immediately upstream of an associated rotor so as to direct the gases onto rotor blades extending from the rotor disc. FIGS. 2a and 2b show a cross-sectional view of one of such stator vanes. The vane 20 comprises a hollow airfoil 22 having a sheet metal body or skin extending in a chordwise direction between a leading edge 24 and a trailing edge 26. The airfoil 22 may be formed from two sheet metals (a pressure side sheet 28 and a suction side sheet 30) joined together to form the airfoil concave pressure and convex suction surfaces. The pressure and suction side sheets 28 and 30 may be joined together, such as by welding, at a leading edge location and at an intermediate location 32 (FIG. 2b) spaced chordwise from the airfoil trailing edge 26.

As best shown in FIG. 2b, the trailing edge portions of the pressure and suction side sheets 28 and 30 meet at the intermediate location 32 (i.e. upstream from the trailing edge 26) and extend therefrom in intimate face-to-face contact down to the airfoil trailing edge 26. Instead of joining the pressure and suction side sheets at the trailing edge by means of a butt joint, a lap joint is rather formed at the intermediate location 32 between the pressure and suctions side sheets 28 and 30. The lap joint may be formed by resistance welding, including spot welding and seam welding. The weld extends over a distance L sufficient to ensure the integrity of the joint between the overlapping portions of the pressure and suction side sheets 28 and 30. The overlapping portions of the pressure and suctions side sheets 28 and 30 extending beyond the weld location 32 define a double skin, weldless, non-tapering airfoil trailing edge section 34. As can be appreciated from FIG. 2b, the airfoil pressure and suction side surfaces are parallel to one another along the full extent of the airfoil trailing edge section 34, thereby providing for a straight airfoil trailing edge profile with a constant wall thickness.

Such a straight airfoil trailing edge profile compared to typical tapered trailing edge profiles may provide less aero losses at the airfoil trailing edge location where the pressure and suction flows have the same vector. Also the straight trailing edge profile provides flexibility to make adjustment of the vane flow area. Indeed, if need be, the airfoil trailing edge section 34 can be cutback, machined or tweak downstream of the joint 32 to provide vane flow adjustment. Trailing edge cutback is obviously not possible for conventional sheet metal vanes having butt joints at the trailing edge.

The provision of the weld at the intermediate location 32 between the opposed inner facing surfaces of the pressure and suction side sheets 28 and 30 provides for a “clean” and smooth trailing edge without requiring grinding and polishing manufacturing steps as in the case of butt joints. The risk that the integrity of the joint be subsequently altered by a surface treatment is avoided.

As shown in FIGS. 3a and 3b, the pressure side sheet 28′ could be shorten closed to the welded joint 32′ to provide a single skin straight trailing edge section 34′. According to this alternative, the suctions side sheet 30′ has greater chord dimensions than the pressure side sheet 28′ and the pressure and suction side surfaces of the straight trailing edge section 34′ are both defined by the suction side sheet 30′. This option, when acceptable from dynamic and stress standpoints, may result in improve dynamics, weight savings and simplified vane adjustment processes.

The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, while the airfoil has been described as being formed of two sheets, it is understood that a single bended sheet could be used to form the pressure and suction sides of the airfoil. The bend would define the rounded leading edge of the airfoil and the opposed terminal ends of the sheet would be joined together at a location upstream of the airfoil trailing edge. Also, it is understood that the trailing edge portions of the sheets could be joint by various bonding or welding processes not only by resistance welding. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.

Claims

1. A gas turbine engine stator vane comprising a hollow airfoil having a sheet metal body with a pressure surface and a suction surface extending chordwise from a leading edge to a trailing edge, the sheet metal body having opposed pressure and suction side trailing end portions that meet at a joint upstream from the trailing edge of the airfoil, the pressure and suction surfaces of the sheet metal body being substantially parallel to one another between said joint and said trailing edge, thereby forming a straight non-tapering trailing edge section from the joint to the trailing edge of the airfoil.

2. The stator vane defined in claim 1, wherein said straight trailing edge section has a constant wall thickness.

3. The stator vane defined in claim 1, wherein said sheet metal body comprises a pressure side sheet and a suction side sheet, said pressure side sheet and said suction side sheet being in face to face contact along the extent of the straight trailing edge section.

4. The stator vane defined in claim 1, wherein said straight trailing edge section is formed from a single sheet.

5. The stator vane defined in claim 1, wherein said sheet metal body comprises a pressure side sheet and a suction side sheet, the suction side sheet having a greater chord dimension than said pressure side sheet and extending chordwise beyond the joint, the straight trailing edge section of the airfoil being formed by the portion of the suction side sheet extending beyond the joint.

6. The stator vane defined in claim 1, wherein the joint is a lap joint.

7. The stator vane defined in claim 6, wherein the lap joint comprises a resistance weld.

8. A gas turbine engine stator vane comprising a pressure side sheet and a suction side sheet joined together to define an airfoil having a leading edge and a trailing edge, said pressure side sheet and said suction side sheet having a trailing end joint which is spaced chordwise from the trailing edge of the airfoil, at least one of the pressure and suction side sheets extending chordwise beyond said trailing edge joint and defining a straight trailing edge section having parallel suction and pressure surfaces.

9. The gas turbine engine stator vane defined in claim 8, wherein only said suction side sheet extends chordwise beyond the trailing edge joint to define said straight trailing edge section of the airfoil.

10. The gas turbine engine stator vane defined in claim 8, wherein said straight trailing edge section is weldless.

11. The gas turbine engine stator vane defined in claim 8, wherein said straight trailing edge section has a constant wall thickness in a chordwise direction.

12. The gas turbine engine stator vane defined in claim 8, wherein the trailing end joint is a lap joint provided between opposed inner facing surfaces of the pressure and suction side sheets.

13. The gas turbine engine stator vane defined in claim 8, wherein said pressure side sheet and said suction side sheet are in face-to-face contact along the extent of the straight trailing edge section.

14. The gas turbine engine stator vane defined in claim 12, wherein the lap joint includes a resistance weld.