发动机壳体辐射噪声预测

Prediction of noise radiated from engine shell

采用虚拟预测方法研究某发动机壳体的振动特性及噪声辐射特性.采用有限元法分析发动机壳体在振动加速度激励下的动态响应,得到壳体表面的振动速度频谱图,并与试验所得壳体上典型点的振动速度频谱图进行对比,仿真结果与试验结果吻合较好.将计算得到的壳体所有外表面节点的振动速度作为边界元模型的输入载荷,导入到声学仿真分析软件中,计算由壳体表面振动而辐射出的噪声,并用声强试验进行验证,对比了理论计算数据与试验数据,两者的噪声分布云图及噪声源中心点处的声强频谱图,并分析了误差产生的原因,结果表明,采用有限元法与边界元法联合求解的方法能够有效地预测出壳体辐射噪声.

The vibration and radiated noise characteristics of the engine shell were analysed by virtual prediction method. The velocity response spectrum of the engine shell was acquired through the method of analysing the dynamic response under the vibration acceleration load by the finite element method. By comparing the theoretical data with the experimental ones for the same points on the shell, good agreements are obtained. The vibration data of the surface of the engine shell＇s points were imported to the acoustic analytic software as the input load of the boundary element model, and the noises radiated from the engine shell by vibration were calculated. The calculated data were testified by sound intensity experiment. The theory data were compared with the experimental data in noise distribution and the center of the noise source＇s intensity spectrum. The results reflect that FEM/BEM has practical significance and can predict the noise radiation from the engine shell effectively.