周向畸变进气下压气机动态失速特性研究

Investigation on Compressor Dynamic Stall Characteristicswith Circumferential Inlet Distortion

关键词:  周向畸变  动态失速  同步压缩小波变换  空间模态  小波相干性  集总系统模型

Key words:  Circumferential distortion  Rotating stall  Synchrosqueezed wavelet transform  Spatial mode  Wavelet coherence  Lumped system model

摘要:

为研究周向畸变进气下压气机动态失速特性，在一大尺寸低转速压气机试验台上进行了均匀进气和180°周向畸变进气下压气机动态失速实验。采用时域观察、频域快速傅里叶变换以及时频域的同步压缩小波变换、基于同步压缩小波变换的空间模态分析和小波相干性分析等方法对动态失速信号进行分析。结果发现，畸变进气下，压气机旋转失速发生前出现0.225倍转子转动频率的一阶模态扰动，该扰动在相对畸变网不同位置区域周向传播速度不一致。宽带非定常扰动在畸变区尾缘附近最强，在畸变区前缘附近最弱，并存在周向尺度转化现象。转子转动频率扰动周向也出现强度变化，最大值出现在非畸变区中心附近的测点。周向畸变条件下集总系统模型对比实验结果的分析表明:实验和模型结果符合较好，旋转失速前非定常扰动周向强度和尺度变化主要受流量系数变化的影响，而一阶模态扰动周向传播速度不均匀现象是畸变进气下压气机系统特性作用的结果。

Abstract:

In order to investigate compressor dynamic stall characteristics with circumferential inlet distortion， the compressor dynamic stall experiments with uniform and 180° circumferential distorted inlet flow were carried out on a large-scale low-speed compressor test rig. The visual inspection in time domain， fast Fourier transform in frequency domain and synchrosqueezed wavelet transform(SWT)， spatial modal analysis based on SWT， wavelet coherence in time-frequency domain analysis methods were used to analyze the dynamic stall signals. The experimental results show that under circumferential distortion condition the first mode perturbation of 0.225 times rotor rotation frequency emerges before rotating stall onset， and the propagation speed is not consistent in different relative circumferential position of the distortion screen. The broadband unsteady perturbation is strongest near the trailing edge of the distorted sector， and weakest near the leading edge of the distorted sector. And the perturbation has a scale transition phenomenon. The rotor frequency disturbance amplitude also changes along the circumferential， the maximum value occurs at the measuring point near the undistorted sector center. The lumped system model with inlet distortion combined with the analysis of experimental results show that the experiment and model results are in good agreement， the circumferential variation of intensity and scale of the unsteady perturbation before rotating stall is mainly affected by the change of flow coefficient， and the uniform circumferential propagation speed of the first mode perturbation is mainly caused by the compressor system with inlet distortion.