Analysis and application of a new type of sweep optimization on cantilevered stators for an industrial multistage axial-flow compressor

Abstract

Sweep is often applied to transonic rotors to reduce the shock loss and to stator vanes to reduce the end-wall separation loss. In this paper, a new type of sweep is created for cantilevered stators in a 5-stage axial-flow compressor through a combined use of sensitivity analysis and an integrated optimization design method. The shape of sweep is focused on the stator hub region according to sensitivity analysis, and the new swept stator design is beneficial for reducing the stator loss at hub end and improving the compressor aerodynamic performance. Firstly, the optimization design of a single first stator row is conducted in the multistage environment, and the aerodynamic benefits gain is mainly due to two aspects. On the one hand, the effect of sweep near the hub reduces the stator inlet Mach number and further reduces the size of supersonic regions and the peak Mach number on the suction surface, thus decreasing the aerodynamic losses. On the other hand, the sweep also reduces the loading in the front part of the blade near the hub and weakens the leakage flow, thus reducing the flow blockage and decreasing the secondary losses in the hub region. After the optimization, the stator loss is reduced by 7.4%, leading to an increment of 0.21% of adiabatic efficiency of the multistage compressor. Secondly, the same optimization strategy is then applied to the remaining stator rows to maximize the aerodynamic benefits gain. The optimized compressor achieves an approximately 1% improvement of adiabatic efficiency over than the baseline one and also performs better over the whole operating range. Simultaneously, the operating range of the multistage compressor is widened. The results indicate that cantilevered stators with the type of sweep in this work have a significant potential to improve the performance of multistage axial-flow compressor.