跨声速压气机转子叶尖泄漏涡非定常特性数值研究

为了研究跨声速单转子压气机系统叶尖泄漏涡的非定常特性，选取Rotor 67孤立转子为研究对象，针对不同背压工况与不同转速工况进行了非定常数值模拟。结果表明:在每一转速状态都存在一非定常边界，其将特性线分为定常部分和非定常部分。当转子运行在特性线非定常部分时，随着背压提高，叶尖泄漏涡脉动频率逐渐减小。这是由于背压提高使叶尖前缘负荷变小，叶尖泄漏涡的驱动力也变小。叶尖泄漏涡的频率特征与转子转速息息相关。高转速状态时叶尖泄漏涡主要表现出低频特征，低转速状态时叶尖泄漏涡主要表现出高频特征。这是由于转速不同，叶尖激波的脱体程度不同，激波对于叶尖泄漏涡的激励位置也不同。由非定常叶尖泄漏涡引起的压力波的周向传播速度在各转速下表现出较强的规律性。随着流量系数的减小，压力波波速呈线性减小趋势，且各转速下减小的速率大致相同。且在波速-流量系数曲线中，各转速的非定常状态起始点基本位于同一条直线。 

Numerical investigation on unsteady characteristics oftip leakage vortex of transonic compressor rotor

In order to study the unsteady characteristics of tip leakage vortex in a single compressor rotor system,a series of unsteady simulations of Rotor 67 were carried out at different back pressures and rotating speeds. The results showed that there was an unsteadiness boundary for each characteristic curve, which was divided into two parts, steady and unsteady. When the rotor operated at unsteady part, the increase of back pressure led to the decrease of frequency of tip leakage vortex. This was attributable to the decrease of tip blade loading near leading edge, finally bringing about the decrease of driving power of tip leakage vortex inception. The frequency of tip leakage vortex was related to the rotating speed of rotor. When the rotating speed was high, the tip leakage vortex showed lower frequency. When the rotating speed was low, the tip leakage vortex showed higher frequency. This was attributable to the detached degree of detached shock wave which was related to the rotating speed, leading to the differences of excitation positions where shock wave stimulated tip leakage vortex. At any rotating speed, there was a strong regularity of circumferential velocity of pressure wave induced by tip leakage vortex. With the decrease of massflow factor, the wave velocity decreased. And the decreasing rates were almost the same at any rotating speeds. In addition, the initial points of unsteadiness at every rotating speed almost stood in a straight line.