横流风机轴向交错叶轮的噪声研究

THE NOISE STUDY ABOUT THE BLOCK-SHIFTED IMPELLERS IN CROSS-FLOW FAN

本文研究了横流风机轴向交错叶轮的气动及噪声特性。首先进行了横流风机的气动性能实验并开展数值解析。用数值解析得到的固壁表面脉动压力进行噪声预测,噪声预测模型采用Farassat 1A方程。在预测过程中对叶轮交错角做出假设,转化成各节叶轮流场的时间延迟,并考虑了风机轴向长度带来的影响。计算结果给出了单一叶片周向旋转噪声辐射的分布情况,分析了噪声源的位置和机理。预测的远场声压从时域和频域与相应的五种具有不同轴向交错角度叶轮的实验结果相验证,揭示了风机的叶片通过频率噪声随叶轮交错角度的变化规律。

The present study focus on the aerodynamic and aeroacoustic properties about the Cross-Flow Fan（CFF） impellers with different block shift angles.The aerodynamic test was carried out and the internal flow was analyzed by CFD simulations.Based on the Farassat 1A equation,the noise about CFF has been predicted by the pressure fluctuations on the surfaces provided by the CFD simulations.The assumption has been made that the shift angle was regarded as a time lag in the flow field of each block and the influence about axial length of impeller is also considered.The noise source was analyzed by the calculated results about the sound distributions of one blade.The predicted far-field noise has been evaluated by the experimental sound pressure waves and spectrums. The relations between discrete noise properties and shift angles have been discussed.