认识缝翼低频噪声的产生机理十分重要，可指导先进的主被动噪声控制方法。本文开展了缝翼噪声的大涡模拟（LES），利用动态模态分解（DMD）方法研究了缝翼低频噪声的产生机理。研究结果表明缝翼低频噪声具有显著的偶极子特性，其利用DMD分析揭示了缝翼噪声的产生机理，缝翼低频噪声源于剪切层中的大尺度涡结构与缝翼下壁面的周期性撞击效应，大尺度涡结构与低频噪声之间存在的流-声耦合的闭环反馈机制，根据反馈机制提出并验证了一种预测低频噪声的理论预测模型。
It is crucial to know the mechanism of low-frequency noise from the leading-edge slat, which can guide an advanced active and passive control of slat noise. According to the highly reliable Large Eddy Simulation (LES), this paper reveals the mechanism of slat noise using the method of Dynamic Mode Decomposition (DMD). The results indicate that the dipole features of slat noise come from the collision between large scale vortexes in the free shear layer and the lower surface of the slat. There is a close loop feedback mechanism of flow-acoustic coupling existing between large scale vortexes and low-frequency acoustic waves from the reattachment point. Based on this mechanism, a theoretical predictive model is also proposed and verified.
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