Optimal Design Criteria of Tandem Configuration for High-Load Compressor Cascades

Axial overlap (AO) and percent pitch (PP) are considered as key position configuration parameters that affect the tandem cascade performance. The objective of the current study is to investigate the optimal design criteria for these two parameters in tandem cascades of subsonic highly-loaded two-dimensional compressors. Before that, the influence mechanisms of AO and PP are explored separately. Research results show that higher PP is beneficial for decreasing rear blade (RB) load, but an invalidity of gap flow occurs when it approaches 1. The change in AO has an influence on the adverse pressure gradient of the front blade (FB), and it also affects the gap flow strength and FB wake development. Then, the optimal design criteria for AO and PP are obtained in a large design space, which clarifies the matching relationship of the two parameters at different operating conditions. The best global range of AO is about -0.05 to 0.05 while PP is between 0.85 to 0.92, and PP should be smaller to avoid performance degradation as AO increases. According to the fault tolerance in practical applications, PP should be closer to the lower bound to ensure that the deterioration boundary is wide enough.