不同叶顶间隙下压气机旋转不稳定性特性

Rotating Instability Characteristics in Compressor with Different Tip Clearances

采用全通道数值计算方法对一台单级低速轴流压气机旋转不稳定性(RI)特性进行分析,研究了4种叶顶间隙条件下RI的频率特性、模态特性和流场特性的变化及原因.采用相干分析方法得到相邻叶片通道内同角度位置压力信号相干函数和互功率谱,显示产生RI流动的通道涡结构在周向的传播特性.空间模态分解和旋转源机理分析得到RI的周向模态特性,影响RI通道涡结构的脉动和旋转特性及其在绝对和相对坐标系下的关系.结果表明:随着叶顶间隙的减小,叶顶流动强度减弱,RI现象强度逐渐减弱,主模态阶数增大.

Rotating instability(RI) characteristics of a single stage low speed compressor are analyzed by full channel numerical calculation method. Variations and the reasons of frequency characteristics, modes characteristics and flow characteristics of RI under four different tip clearances are investigated. The coherence analysis method is used to obtain the coherent function and the mutual power spectrum of the pressure signal at the same angle in the adjacent blade channel, which show the propagation characteristics of the channel vortex structure with flow in the circumferential direction. The circumferential modal characteristics of RI, the pulsating and rotating characteristics of channel vortex structures affecting RI as well as its relationship in absolute and relative coordinate systems are obtained by spatial mode decomposition and rotation source mechanism analysis. Results show that with the decrease of tip clearance, the flow intensity of tip clearance decreases, the intensity of RI gradually decreases, and the order of main modes increases.