Unsteady Analysis of a Generic Non- Axisymmetric Hub Endwall Contour as Applied to a Rotating Turbine at On and Off- Design Conditions

Abstract

Numerous researchers have investigated various techniques to reduce loss in gas turbine engines. One such technique that has shown promise is endwall secondary flow control using non-axisymmetric endwall contouring. Previous steady state investigations have shown that the generic endwall contour designed for a cascade reduced the loss in a rotating turbine test rig. The current investigation was to determine if there were unsteady effects introduced by the contour at design and off design conditions. An experimental and numerical study was performed to investigate the rotor flow field for any unsteady changes to the rotor exit flow field. The investigation was performed at an increased loading condition, design and a decreased loading condition to determine how changes in operating condition altered the flow field. The experimental results showed that the velocity magnitude of the hub endwall secondary flow vortex system for the contoured rotor was reduced. The peak difference in oscillation of the flow was also reduced. The effect of the endwall contour reduced the over and under turning of the endwall secondary flow vortex system as well. The magnitude of the FFT at the blade passing frequency was reduced below midspan.