Research on effectiveness of casing optimization contouring on performance of transonic rotor

In order to study the effects of casing optimization contouring on the performance of transonic compressor, a transonic rotor was investigated with numerical simulation. Comparison and analysis of the flow field near the tip and the overall performance were performed before and after casing contouring near the design point and near the stall point. The results show that casing contouring could improve the tip flow field and the compressor performance. It is found that the efficiency was improved at the whole working condition by about 0.25% near the design point and 0.33% near the stall point. The total pressure ratio was improved by about 1.1% near the stall point, however, the total pressure ratio remained unchanged near the design point. Casing contouring reduced the loads at the leading edge of the blades and changed the 3D structure of shock wave by making it move backward slightly. Near the design point, casing contouring improved the efficiency at most of blade span. After casing contouring, two low pressure circles appeared near the casing which produced the 3D pressure gradient effects and this changed the vortex form in meridional surface near the circles, and it mitigated the effects of the low velocity recirculation zone because of the forward direction gradient. The streamline at the tip became more reasonable and the double-leakage phenomenon disappeared. Near the stall point, casing contouring improved the total pressure ratio at most of blade span and the vortex form did not change, but the position of vortex core changed. The streamline at the tip became more reasonable, while the double-leakage phenomenon did not vanish.