高压涡轮转子间隙泄漏流动的非定常特征研究

Study of unsteady tip leakage flow characteristic in high pressure turbine stage

利用数值方法求解三维非定常雷诺平均Navier-Stokes方程模拟某跨声速高压涡轮流场,研究了某跨声速高压涡轮流场的非定常特征,通过详细分析动静干涉对间隙泄漏流动的影响,进一步明确了泄漏流周期性变化的规律和成因.研究发现:静子尾缘燕尾波的外侧分支外尾波是间隙内部流动结构变化的主要原因,间隙泄漏涡的周期性变化则受外尾波和尾迹的共同影响.外尾波深入转子通道内部周期性经过间隙,在间隙前缘附近产生很强的逆压梯度,使间隙前部流动方向明显改变而产生大范围分离.外尾波导致间隙泄漏流量明显增加并周期性震荡.在静子尾迹和外尾波共同作用下,泄漏涡强度出现波动且涡的位置前后移动,使泄漏涡呈现明显的非定常性.

Three-dimensional time-dependent Reynolds averaged Navier-Stokes equa- tions were solved to investigate the unsteady tip leakage flow in a transonic high pressure turbine stage. The changing rules of tip leakage flow as well as the reasons were indicated based on the study of the effect of stator trailing edge wake and shock waves. Results show that the outboard branch of the waves causes the periodic modification of the flow inside the tip clearance, while the stator trailing edge wake and wave make the leakage vortex changes together. The shock wave goes deep into the passage of the rotor and passes through the tip clearance periodically. When the shock wave passes the tip clearance, a strong adverse pres- sure gradient appears nearby the leading edge of the clearance. In addition due to the adverse pressure gradient, the separation bubble grows and a separation phenomenon appears at the forepart of the tip clearance. Meanwhile, the leakage flowmass increases and reverberates as the result of the shock wave. Because of the effect of both stator trailing edge wave and shock waves, the strength of the vortex attains to a momentary peak value, and the location of the leakage vortex moves front and back, and both of the phenomena indicate that the leakage flow is marked unsteady.