离心风机蜗壳振动声辐射的定量预测

  目的  为开展离心风机振动噪声预报，  方法  首先，对离心风机整个流域进行结构化网格划分，采用大涡模拟（LES）获得叶轮表面随时间变化的脉动力，以旋转偶极子辐射为模型，采用声学有限元方法计算管道中的辐射声；然后，以蜗壳部分的壁面偶极子为辐射源，计算壁面脉动压力辐射声；最后，将数值计算结果与试验结果进行对比分析。  结果  结果表明，蜗壳壁面脉动压力辐射声在低频段高于叶轮辐射声，而在高频段低于叶轮辐射声；数值计算结果与实验结果具有一致性。  结论  所提叶轮辐射声及蜗壳壁面脉动压力辐射声的预报方法可满足工程应用需求。

Quantitative prediction of sound radiation by casing vibration of centrifugal fan

  Objectives  In order to predict the vibration noise of centrifugal fan,  Methods  the whole flow field is meshed by the structured grid and the fluctuating force on the impeller surface that varies with time is obtained by using the Large Eddy Simulation(LES)method. Using the rotating dipole radiation model, the noise from the pipe is predicted by the acoustic finite element method. Taking the surface dipole in the volute wall as the sound source, the noise from the wall pressure fluctuation is calculated and compared with the test results.  Results  The results show that the flow noise from the wall is higher than that of the impeller in the low frequency band, but lower in the high frequency band and have a good agreement with the test results.  Conclusions  The prediction methods for impeller noise and volute wall pressure fluctuation noise can meet the engineering application requirements.