Validation of the time-space collocation method in simulating the inlet distortion flows in transonic compressor

The aerodynamic performance of transonic compressor, especially the stall margin will be significantly influenced by inlet distortion. The time marching method is often used to simulate such flow phenomenon, but it is extremely time-consuming. To achieve a better balance between accuracy and computational cost, a novel time-space collocation method is proposed to simulate inlet distortion flows in transonic compressor. In this method, the perturbations of the unsteady flow variables are approximated by a linear combination of temporal and spatial Fourier disturbances. Consequently, the solving of unsteady flow governing equations is converted to obtain the steady-state flow filed of several selected temporal and spatial samples. The effectiveness of this method were validated by simulating the unsteady flows in a two-stage compressor with circumferential inlet total pressure distortion. Notably, the interaction effects of adjacent blade rows have little impact on the dominated flow patterns caused by inlet distortion, thus these can be ignored when evaluating the performance degradation due to inlet distortion. The results show that employing three spatial harmonics is enough to resolve the dominant effects of inlet distortion. About an order of speed-up was achieved compared to the time marching method, indicating that the time-space collocation method has promising engineering applications.