Effects of tip leakage flow on aerodynamic performance of a low-reaction transonic rotor

In order to study the effects of the tip leakage flow on the aerodynamic performance of a small aspect-ratio highly-loaded transonic rotor, numerical simulation is carried out for analysis of the all operating conditions and flow structures near the tip at different tip gap in detail. The results show that, under the condition of zero tip gap, the rotor has the highest peak efficiency while the narrowest working range. The existence of leakage flow could suppress the development of the corner separation in the flow passage, which helps to delay the triggering of stall and raise the rotor stall margin by 20%. The tip leakage vortex is broken down after interacting with the shock wave at a higher tip gap, however, adoption of the low-reaction design idea could control the broken vortex not to spread in a large extend. This could guarantee a higher efficiency for the rotor even at near stall condition. Taking all the aerodynamic aspects into consideration, for this kind of rotor, an optimal tip gap should be existed.