Effect of tip leakage flow and ejection on stall mechanism of transonic tandem rotors

In order to investigate the stall mechanism of transonic tandem rotor, the transonic tandem rotor tip flow field in different tip clearance was studied. The results show that the flow field of zone two has a great effect on stall and it is determined by the tip leakage flow and ejection. Furthermore, the tip leakage flow and ejection are determined by the tip clearance. When the forward blade tip clearance is large, the tip leakage flow is much stronger and becomes the leading factor of zone two. Thus, forward blade becomes the stall position. When the forward blade tip clearance is reduced, ejection grows stronger and becomes the leading factor of zone two. This leads that the stagnation area of the tip leakage flow in zone two reduces and after blade becomes the stall position. The forward blade tip clearance has more effect on stall than the after blade tip clearance. What's more, after blade tip clearance has little effect on the tandem rotor when forward blade is the stall position.