Blade interaction between shock wave and impellor

Numerical study about unsteady flow field in one transonic compressor with fatigue crack at impellor hub is presented, in which main interest is focused on mechanism and influence of shock wave/impellor interaction. Results show that shock wave/impellor interaction follows the general law involved in intersection of shock wave and solid wall. Wide wake and small gap between impellor and diffuser make the shock wave in diffuser change rapidly and greatly. These changes include the transformation between shock wave and compression wave, the number of shock wave and large oscillation of shock wave or compression wave in diffuser passages. The depth that up-extended bow shock of diffuser run into impellor is determined by shock wave strength and wall shape near the diffuser leading edge. High frequency and large amplitude of stress oscillation induced by up-extended bow shock may lead to high cycle fatigue. This might be the main reason of fatigue crack that takes place at the hub of this impellor.