转子叶栅非同步振荡发声特性研究

轴流压气机转子叶片排振荡疲劳失效是常见的气动弹性失稳问题。当转子叶栅处于非同步振荡状态下时,压气机管道内部将伴随着异常噪声的产生,这类噪声的频率既不是分布在叶片通过频率及其谐波上,也不是分布在转子轴频率及其谐波上,同时也不满足简单多普勒效应。为了解释这种异常噪声现象,以三维升力面理论为基础,讨论叶片对其附近流体施加非定常载荷的发声问题,给出了转子叶栅振荡异常发声问题的物理解释,建立了声场频率及模态特性与转子声源特性的直接关系式,并给出了频率特性不同于叶片通过频率且不符合简单多普勒效应的完整解释。在此基础上,通过机理性实验研究证实了该模型的正确性。实验结果表明,理论预测声场的频率和周向模态特性与实验结果完全一致。

Investigation of sound generation by non-synchronously vibrating rotor blades

The blade fatigue failure is a common aeroelastic problem of axial compressor. The phenomenon accompanied with blade vibration is abnormal acoustic field generation in compressor duct. The frequency of sound field generated by non-synchronously vibrating rotor blades is unequal not only to the compressor rotational frequency, but also to the blade passing frequency that is identical with sound generated by stator and rotor interaction. Meanwhile the frequency cannot be explained by typical Doppler shift phenomenon. In this paper, a theoretical model based on the three-dimensional lifting surface theory has been built to demonstrate the frequency and circumferential modal characteristics of the sound generated by rotor blades vibration. The developed model illuminates the fact that the sound frequency and circumferential mode depend a lot on the inter-blade phase angle. The experiment results verify the relationship between sound generation and blades vibration given by the model.