压气机叶顶泄漏流振荡周向传播特性的数值模拟

通过对一低速轴流压气机转子的叶顶泄漏流的振荡特性进行数值研究,发现在大流量工况下,叶顶流场随时间不发生变化.随着流量减小,叶顶流场逐渐产生脉动,同时叶顶泄漏流发生周期性振荡,表现为叶顶泄漏涡的产生位置、涡结构形态及撞击在相邻叶片的位置随时间发生变化.叶顶泄漏涡及其导致的脱离涡会导致相邻叶片表面产生低压区,因此叶顶泄漏涡的振荡导致了叶片顶部压力分布的脉动,进而影响了相邻流道叶顶泄漏流的产生.这个叶顶泄漏流与相邻叶片的干涉作用是叶顶流场产生振荡的主要原因.而且,叶顶泄漏流在相邻流道间的振荡状态存在相位延迟,这导致了一个以非叶片数为周期的流动扰动结构绕转子旋转. 

Numerical simulations on circumferential propagating characteristics of tip leakage flow oscillation in compressor

Through numerical investigations on the characteristics of tip leakage flow oscillation in a low speed axial compressor, it was found that at large flow rate conditions, the tip flow field did not vary with time. As flow rate decreased, the tip flow field gradually started to fluctuate, meanwhile the tip leakage flow oscillated periodically, showing that the origin position, vortex structure pattern and impinging position on the pressure surface of neighboring blade changed with time. The tip leakage vortex and its detached vortex induced low pressure regions on the neighboring blade surface, leading to the oscillation of pressure distribution in blade tip region. Then this also affected the generation of the tip leakage flow in the neighboring passages. The interaction effect of tip leakage flow and the neighboring blade was the main cause of the tip flow field fluctuation. Furthermore, the tip leakage flow oscillations had phase lag between neighboring blade passages, which induced a flow disturbance with non-blade-number periodicity propagating circumferentially around the rotor.