Patent Application
20110081238
The application relates generally to gas turbine engines and, more particularly, to gas turbine engine vanes.
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.
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.
Reference is now made to the accompanying figures, in which:
a is a cross-sectional view of an embodiment of a stator vane suited for use in the engine shown in
b is an enlarged cross-sectional view of a trailing edge section of the stator vane shown in
a is a cross-sectional view of another embodiment of the stator vane; and
b is an enlarged cross-sectional view of a trailing edge section of the stator vane shown in
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.
As best shown in
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
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.
