压气机内部噪声特征与转子叶片声固耦合机理分析

航空发动机压气机转子叶片故障多由机械激励和气动激励造成，而高强声波对转子叶片的激振因素不容忽视。通过开展某型涡扇发动机压气机内部噪声测试试验，研究压气机转子叶片振动机理及其与噪声信号的对应关系。阐述了压气机内部旋转不稳定性非定常压力波作用机制，提出了基于刚性壁声波导管技术的导出式噪声测量方法，完成了某型涡扇发动机压气机内部噪声信号测试，对噪声信号进行了频谱分析和声传播特性分析。研究结果表明，某型涡扇发动机压气机内部噪声信号频谱呈现高峰值纯音分量1 402 Hz，并且该纯音分量与转子叶片通过频率呈现特定的频率组合关系。该纯音分量的噪声源在压气机内部沿发动机顺航向方向从后向前传播。利用旋转不稳定性理论，将声源频率在不同坐标系下进行转换，当噪声源周向模态数为13时，该纯音分量可调制出与高压一级转子叶片一阶振动频率相对应的激振频率。

Analysis of noise characteristics and acoustic structure coupling mechanism of rotor blades in compressor

The rotor blade fault of aero-engine compressor is mostly caused by mechanical and aerodynamic excitations. The excitation factors of high intensity sound waves to rotor blades should not be ignored. Based on the noise testing in a turbofan engine compressor, the vibration mechanism of compressor rotor blades and its corresponding relation with noise signal have been investigated. The mechanism of rotating instability unsteady pressure wave in the compressor is expounded. A noise measurement method which based on rigid wall acoustic waveguide is proposed. The internal noise signal testing of the turbofan engine compressor is completed. And the noise signal spectrum and acoustic propagation characteristics are analyzed. The results show that, the internal noise signal spectrum of the turbofan engine compressor presents a peak pure tone component of 1 402 Hz. And this tone component has a specific combination of frequencies with rotor blades. The propagation direction of this tone component noise source is from the back to the front in the airflow direction in the compressor. The noise source frequency is transformed in different coordinate systems based on the rotating instability theory. When the circumferential mode number of the noise source is thirteen, this tone component can modulate the excitation frequency corresponding to the first order vibration frequency of the first stage rotor blades of the high compressor.