Loss reduction in a high-speed compressor cascade using an L-shaped endwall groove to generate a streamwise vortex

Abstract

Reducing the endwall loss is essential for the development of high-efficiency aero-engine compressors. An advanced vortex generation technique, using an L-shaped groove in the endwall, has been applied to a high-speed linear compressor cascade to manipulate the complex endwall flow and hence reduce associated aerodynamic loss by means of an induced streamwise vortex. A geometry generation method for the L-shaped endwall groove has been developed for the purpose of facilitating the design of the L-shaped groove. Hereafter, the L-shaped endwall groove has been optimized through a surrogate-based optimization framework. The numerical results demonstrated that the optimal L-shaped groove could control the endwall flow effectively and achieve a significant loss reduction at all operating points that were considered. At the design point, the calculated total pressure loss coefficient was decreased by 17.9%, with the static pressure rise increasing by 5.53%. The flow underturning and loss away from the endwall were reduced, while the flow overturning and loss near the endwall increased. The analysis of the flow-control mechanism indicated that the groove separation vortex, i.e. the streamwise vortex generated by the L-shaped endwall groove, presented a barrier to the endwall cross flow, mitigating the interaction of the endwall fluid with the suction side of the blade.