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基于叶片外形优化的轴流风机降噪设计

Noise reduction design of an axial flow fan based on shape optimization

  • 摘要: 针对某型轴流风机气动噪声问题,采用分离涡和声类比相结合的方法,分析了轴流风机的气动与噪声特性。在航空工业空气动力研究院半消声室进行了测试,以验证数值结果的可靠性。通过模拟分析产生噪声的位置确定、明确降噪方向。通过调整动叶结构分布和静叶安装角进行风机噪声优化,评估了降噪设计后的效果。结果表明,叶顶泄流导致动叶叶顶1/3处出现较大范围的低压区,同时静叶叶片后缘流动分离较为严重,导致该型号风机除了在倍频处产生较大的纯音外,在5000~8000 Hz频段内仍有较高的宽频噪声。通过改变动叶外形、扭转静叶安装角,能够减小叶顶泄露涡强度,降低泄露涡与静叶之间相互作用,抑制叶频、二倍频及三倍频处的噪声,在指定监测点处降噪量可达2.2 dB(A)。

     

    Abstract: Aiming at the aero-acoustics problem of an axial flow fan, the aerodynamic and acoustic characteristics of the axial flow fan are analyzed by using detached eddy simulation (DES) and the acoustic analogy method. Based on the semi-anechoic chamber of AVIC Aerodynamic Research Institute, the noise is tested to verify the reliability of the numerical method. By analyzing the reasons for noise production, the design direction is determined. By modifying the structure of the moving blades and adjusting the mounting angle of the stationary blade, the aerodynamic noise of the fan is optimized, and the effect is analyzed. The results show that tip leakage flow leads to a larger low-pressure zone in the 1/3 chord length of the blade, causing severe flow separation around the trailing edge of the stationary blade, resulting in higher tonal noise at 1BPF and higher broadband noise in the range from 50008000 Hz for this axial flow fan. By changing the shape of the blade and adjusting the mounting angle of the stationary blade, the strength of the tip leakage flow vortex is reduced, and the interaction between the tip leakage flow vortex and the stationary blade is weakened. The noise at 1BPF, 2BPF, and 3BPF is reduced. The total noise reduction at a specific monitoring point reaches up to 2.2 dB(A).

     

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