风机叶片掠过频率噪声的等效激励源辨识方法

Identification Method of Equivalent Excitation Source for Fan Blade Passing Frequency Noise

离心风机流体激励源位于风机内部,并且是分布式的激励源,可以通过计算流体力学(computational fluid dynamics,简称CFD)分析计算激励力分布,但无法通过表面的动力响应来反求激励力,验证CFD结果的正确性。针对此问题,建立了风机叶片噪声的等效激励源辨识方法,用实验的方法获得蜗壳振动大小以及候选等效激励点到蜗壳振动测点的传递函数,测量了离心风机在额定工况下的压力脉动大小,通过多项式拟合得到了蜗壳面上的压力脉动分布,为等效源选择提供依据。通过最小误差算法优化选择等效激励源候选点,根据Tikhonov正则化算法反演得到等效激励力大小,再用测量得到的传递函数与反演得到的等效激励力计算蜗壳、机脚等位置的振动响应,来验证反演结果的等效性与准确性。主要的叶片掠过频率峰值反演结果与测量结果误差在2 dB左右,成功反演了离心风机叶片掠过频率等效激励力。

The fluid excitation source of centrifugal fan is located in the fan,and it is a distributed excitation source.The distribution of the excitation force is calculated by computational fluid dynamics(CFD)analysis,but it is not able to calculate the excitation force through the dynamic response of the surface to verify the correct⁃ness of the CFD results.The identification model of the equivalent excitation source is established.The vibra⁃tion of the volute and the transfer function from the candidate equivalent excitation point to the vibration mea⁃surement point of the volute are obtained by experiments.The pressure fluctuation of the centrifugal fan operat⁃ing at the ratings is measured.The pressure fluctuation distribution on the volute surface is obtained by polynomi⁃al fitting,which provides the basis for the selection of the equivalent source.The minimum error algorithm is used to optimize the selection of equivalent excitation source candidate points and inversion measurement points,and the equivalent excitation force is obtained by Tikhonov regularization algorithm inversion.Then the measured transfer function and the inversion equivalent excitation force are used to calculate the vibration re⁃sponse of the volute and motor mount,to verify the equivalence and accuracy of inversion results.The error be⁃tween the inversion result and the measurement result at blade passing frequency is about 2 dB,and the equiva⁃lent excitation force inside the centrifugal fan is successfully inverted.