Non-Axisymmetric Endwall Profiling in a Turbine Rotor Blade

A non-axisymmetric endwall profile has been designed using CFD with the aim of reducing endwall pressure non-uniformities downstream of a rotor blade. The purpose was to reduce coolant leakage as proposed by Rose (1994). This profile has been manufactured and fitted to the Durham linear cascade. The experimental endwall pressure distribution agrees very well with the CFD predictions giving a substantial reduction in pressure non-uniformity at the equivalent of the platform edge location downstream. Velocity and total pressure measurements have also been made within and downstream of the blade row to investigate the effects of the profile on the cascade secondary flow. Although the experimental results indicate no significant increase in the secondary flows, a small increase in loss is seen. The CFD predicts these trends also but to a smaller extent. This investigation suggests that with three-dimensional endwall design, the pressure field which provides the driving force of secondary flows can be modified without blade redesign.