某跨音速轴流压气机转子叶顶泄漏流的非定常特征

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

本文采用数值模拟方法研究了某跨音速轴流压气机转子在设计间隙、不同流量工况下叶顶泄漏流非定常流动特征。结果显示该转子在大部分工况下都出现非定常波动现象。静压均方根值分布表明非定常波动现象主要存在于叶顶,是由叶顶泄漏流自激非定常性引起,激波及波涡干涉位置附近波动不明显。针对小流量工况,分析了泄漏流的非定常特征和叶顶拟S1流面瞬态静压在一个波动周期内随时间的变化规律,并详细阐述了间隙中部叶顶两侧压差与泄漏流速度之间的动态循环过程。随流量减小,叶顶非定常波动频率减小,波动强度增强,压力面最强的波动区域向前缘移动。

Effect of mass flow rate on unsteadiness of tip leakage flow for a transonic rotor is investigated by numerical simulation. It is found that among all the simulated cases, the unsteadiness exists at most operating conditions. Root Mean Square contours of static pressure distribution illustrates that the strongest fluctuating region is located on pressure side of blade influenced by the tip leakage vortex, which is originated from tip leakage vortex. The oscillation near the shock wave and location of shock/vortex interaction are very weak. Instantaneous flow fields in one period at operating condition with small mass flow rate show that the mechanism of unsteadiness and the interaction between pressure difference and tip leakage velocity. With the decrease of mass flow rate, the frequency of unsteadiness decreases, the strength of fluctuation is intensified, and location of the strongest fluctuation on the pressure side of blade moves upstream.