Flow passage for gas turbine engine
Inefficiencies associated with the formation of horseshoe vortices in a gas turbine engine having a row of radially extending airfoils, are mitigated with an improved flow passage defined by the suction and pressure surface of two adjacent airfoils and endwalls (disposed proximal to the radially inner and outer ends of the airfoils). The flow passage includes a ridge disposed in one of the endwalls adjacent a suction surface of one of the airfoils, the ridge extending longitudinally from a location at or near the maximum circumferential extent of the airfoil suction side to a downstream location proximal to the trailing edge of the suction surface.
1. A flow passage for a gas turbine engine having a longitudinal axis, said flow passage comprising a pressure surface and an opposed suction surface of two circumferentially spaced radially extending airfoils, and two radially spaced endwalls disposed proximally to the radially inner and outer ends of said airfoils, said flow passage further comprising an elongate ridge projecting radially from one of said endwalls adjacent said suction surface of one of said airfoils, said ridge including an upstream end disposed generally at the location of the maximum circumferential expanse of said suction surface and a downstream end disposed proximally to the trailing edge of said suction surface, the remainder of said endwall being generally uninterrupted.
2. The flow passage of claim 1 , wherein said gas turbine engine includes high and low pressure turbines and said airfoils comprise two stator vanes located in a transition duct disposed longitudinally between said low and high pressure turbines, said endwalls comprising radially inner and outer flow surfaces of said transition duct.
3. The flow passage of claim 1 , wherein said elongated ridge projects from a radially inner one of said endwalls.
4. The flow passage of claim 1 , wherein said ridge has an upstream end and a downstream end, said upstream end of said ridge being generally biased toward said suction surface.
5. The flow passage of claim 1 , wherein said downstream end of said ridge fairs into said endwall from which said ridge projects.
6. The flow passage of claim 1 , wherein said ridge is convex along substantially the entire length thereof.
7. The flow passage of claim 6 , wherein said ridge includes a peak having a smooth, convex, curvilinear surface.
8. The flow passage of claim 1 , wherein said trailing end of said ridge is axially disposed generally within the downstreammost 20% of the axial chord line of said suction surface.
9. The flow passage of claim 1 , wherein said ridge is of a height generally between 1% and 20% of the span of said airfoil having said suction surface.
10. The flow passage of claim 1 , wherein said ridge is generally contiguous to said suction surface.
11. A gas turbine engine transition duct disposed between low and high pressure turbines thereof, said transition duct including coaxial radially inner and outer duct walls and a pair of circumferentially spaced radially extending airfoil shaped guide vanes disposed therebetween, said radially inner duct wall including an elongated ridge projecting radially inwardly from said inner duct wall, said ridge having an upstream end disposed generally at the location of the maximum circumferential extent of said suction surface and a downstream end disposed proximally to the trailing edge of said suction surface.
12. The gas turbine engine transition duct of claim 11 , wherein said upstream end of said ridge is biased toward said suction surface.
13. The gas turbine engine transition duct of claim 11 , wherein said downstream end of said ridge fairs into said inner transition duct wall.
14. The gas turbine engine transition duct of claim 11 , wherein said ridge is convex along substantially the entire length thereof.
15. The gas turbine engine transition duct of claim 14 , wherein said ridge includes a peak having a smooth, convex curvilinear surface.
16. The gas turbine engine transition duct of claim 1 , wherein said downstream end of said ridge is axially disposed generally within the downstreammost 20% of the axial chord line of said suction surface.
17. The gas turbine engine transition duct of claim 11 , wherein said ridge is of a height generally between 1% and 20% of the span of said vane having said suction surface.