Aerodynamic Noise Characteristics During Evolution of Rotating Stall in Centrifugal Fan

基于节流阀函数及宽带噪声源模型，对电厂常用的G4？73型后向式离心风机在旋转失速状态下的气动噪声特性进行了数值研究。分析离心风机分别在设计工况、失速先兆的产生过程、失速先兆发展为失速团的三维演化过程及失速团沿周向传播过程中风机内部的气动噪声特性，揭示了旋转失速非稳定流动现象对气动噪声分布的影响规律。结果表明，失速先兆发生后叶轮附近旋涡噪声对应的高噪区经历了沿径向、周向和轴向的三维非定常演化过程，高噪区从两个变为一个；失速发生后，旋涡噪声占主要部分，高噪区保持与失速团相同的速度沿周向传播。文中分析了失速团与蜗舌对离心风机气动噪声的影响机制。研究结果对完善旋转失速的理论体系及通过噪声对旋转失速进行预估具有重要意义。

Rotating stall is a kind of unsteady flow instability which occurs in the centrifugal fan under low flow rate conditions. After the occurrence of rotating stall, due to the relative motion between the stall cells and the impeller, the internal flow field can be destroyed and the aerodynamic noise will increase. Even the fatigue fracture of blades can be induced by the additional aerodynamic loads at the high stress point. Therefore,