The investigation of tip leakage flow of circumferential skewed axial fan at off-design condition by PIV

In this paper,the instantaneous velocity and vorticity distributions in the tip region of lower pressure axial fans with circumferential forward-skewed,backward-skewed blades are successfully measured with the PIV system at off-design condition.Based on the measurement results,the evolution of the tip leakage vortex in circumferential skewed blades is discussed.The measurement results show that at peak pressure condition,the instantaneous characteristic of the tip leakage vortex in circumferential skewed blades is observed;the tip leakage vortex of circumferential backward-skewed blade generates and breaks down earlier and interacts more violently with mainstream than that of forward-skewed blade,which causes large blockage and much loss.The circumferential forward-skewed blade seems to be efficient to control the tip leakage flow.