Full-annulus numerical investigation of axial flow compressor with self recirculation casing treatment

Effects on the performance and flow-field of subsonic axial-flow compressor are investigated with full-annulus numerical method with two kinds of self recirculation casing treatment, which are different in the number of self recirculation setting. The unsteady numerical calculative results show that stall margin improvement from 6.3% to 9% is achieved with two kinds of self recirculation casing treatment. The fundamental flow mechanism is obtained by detailed analyzing the flow-filed at the blade tip and the underlying mechanism consists of: (1) Leading edge spilling flow can be restrained by the high speed injecting flow coming from self recirculation casing treatment and consequently the flow-filed of blade tip passage is improved effectively. (2) When increasing the number of self recirculation setting from 10 to 15, the frequency of injecting flow affecting tip leakage flow is improved. As the result, the ability of casing treatment to restrain the negative effects of tip leakage flow is enhanced.