跨音速轴流风扇转子叶顶泄漏流的数值研究

NUMERICAL SIMULATION ON UNSTEADY TIP LEAKAGE FLOW IN A TRANSONIC AXIAL FAN ROTOR

采用数值模拟方法研究了不同间隙、不同流量工况下叶顶泄漏流非定常流动特征,发现在研究的三个间隙中,只有当间隙大于或等于设计间隙时,流动才会出现非定常性。随着流量的减小,泄漏涡轨迹前移,当泄漏涡轨迹到达相邻叶片压力面时,影响压力面压力分布,打破流场静态平衡,引起叶顶流场及激波位置、强度发生非定常波动。

Effects of tip clearance size and mass flow rate on unsteadiness of tip leakage flow are investigated by numerical simulation. NASA Rotor 67 is chosen as the computational model. It is found that among all the simulated cases, the unsteadiness exists when the size of the tip clearance equals or larger than design tip clearance of the computational model. With the decrease of mass flow rate for a fixed tip clearance size, trajectory of tip leakage vortex moves upstream, resulting in tip leakage flow influences the pressure distribution on the pressure side of adjacent blade in the tip region. The instantaneous flow fields in the blade tip region show it is the unsteadiness of tip leakage flow that causes the unsteady flow, and thereby leads to weak oscillation of shock wave.