Tip leakage flow in lower pressure axial flow fans with circumferential forward-skewed

backward-skewed and radical blade

were investigated numerically at the off-designation conditions and validated experimentally.The circumferential skewed effects on origination and development of tip leakage vortex were discussed according to flow rates.The results show that as flow rates decrease

tip leakage vortex origination move towards the leading edge

and circumferential skewing strengthen the mixing between tip leakage vortex and main flow;tip leakage vortex of forward-skewed blade is located most far from leading edge

vortex strength is weakest

and movement is slowest.The circumferential forward blades stabilize tip leakage flow

decrease end-wall losses at off-designation conditions and improve stable operation rang.