Mechanism of corner separation in high-load compressor: A new corner profiling method based on optimization

Three-dimensional corner separation, a complex flow phenomenon in highly loaded axial compressors, severely hampers the improvement of compressor performance. Solving the aerodynamic problems caused by three-dimensional corner separation has become a key to improving the axial compressors on multiple working conditions. To alleviate the separation and reduce loss, the investigation in this study proposed a new corner profiling optimization method based upon the profiling shape factors. The parameterized suction surface is controlled by a third-order Fourier series along the axial direction and an inverse proportional function along the span, which expands upon the flexible variation of corner profiling methods by incorporating five shape factors. Then, five separation optimizations based on shape factors are performed for a highly loaded compressor cascade on design and stall conditions. The main goal of the current investigation is to strengthen the corner profiling range, determine the suitable shape factor on multiple working conditions, and summarize practical design guidelines. The flow field analysis of optimization results, based on different shape factors, shows that the optimal profiling effectively weakens corner separation. Due to the difference in main factors affecting the compressor performance on the design and stall conditions, the overall performance of the compressor can be improved when the profiling structure is concave at the leading-edge and convex at the trailing-edge on the design condition or a larger convex in the entire chord range on the stall condition. Given that the blade re-design needs to meet multiple working conditions, a profiling structure with convex at the leading-edge and trailing-edge and concave at the middle is the best choice.