Design Optimization of a HP Compressor Rotor Blade and Its Hub Endwall

The present contribution focuses on the design of a non axisymmetric hub endwall of a HP compressor single-row rotor blade in order to improve its performance at nominal conditions. First, the validation of the optimization chain is performed with a blade shape optimization based on 48 parameters with the aim to maximize the isentropic efficiency of the HP compressor at two different operating points and with two different tip gap values. The non axisymmetric hub surface is then parameterized with 16 design parameters that can create circumferential 3D bumps and hollows of variable amplitude and length at two main control sections that follow the blade curvature. The optimized non axisymmetric hub yields a 0.4% increase of the isentropic efficiency compared to the axisymmetric case by influencing more the shock mechanism close to the wall rather than the secondary flows.