Flow mechanisms of improving compressor performance through self recirculation casing treatment

Self recirculation casing treatment is known as an effective method to improve axial compressor performance and flow field. It is implemented by combining injection and bleed on the compressor shroud and has the characteristic of injecting or bleeding quantity self adjusting with the compressor work point varying. Effect of self recirculation casing treatment on the performance and flow field of NASA axial Rotor37 is performed with unsteady numerical method to explore the mechanism of self recirculation casing treatment affecting the performance and flow field of transonic compressor. The numerical results show that self recirculation casing treatment not only can suspend the stall effectively but also improve the compressor efficiency appreciably in the range of flow rate studied. The detailed analysis of the flow field at the blade tip shows that the magnitudes of flow inlet angle is increased and the development of tip leakage vortex is restrained with self recirculation casing treatment, which can prevent he breakdown of the clearance leakage vortex and improve effectively the current ability of blade tip passage. As the result, the loss of rotor tip area is receded.