Non-Axisymmetric Endwall Profiling in the HP NGV’s of an Axial Flow Gas Turbine

Abstract

The Nozzle Guide Vanes (NGV’s) of an axial gas turbine generate circumferential non-uniformities in static pressure after their trailing edges. This paper aims to show that these non-uniformities can be removed locally by re-shaping the hub endwall. The ultimate objective is to improve engine performance by cutting the leakage of coolant from the disc rim seal. The technique is demonstrated theoretically using 3D viscous CFD. The required endwall shape is non-axisymmetric and is generated parametrically by altering a calculation grid for an existing NGV. The results show a reduction of the static pressure non-uniformities by 70%. Other favourable effects are also predicted and are commented upon.