一种考虑薄壁散射效应的声学计算模型

An acoustic numerical model considering scattering effect of the thin-body

采用薄壁边界元/FW-H理论混合方法建立了考虑薄壁声学散射效应的数值计算模型。这种声学计算模型可以预测存在薄壁如风扇机匣、蜗壳等条件下的声波的传播及散射问题。计算模型的建立主要包含噪声源的计算和声源的传播两方面:首先建立FW-H的频域方程,并采用计算流体力学方法计算流场,通过流场数据计算气动噪声源;然后采用薄壁面边界元法计算固壁对声波的散射,并计算声波在固壁散射后的声场分布。数值计算结果和实验结果及经典的叶轮机管道风扇噪声理论进行了对比,结果表明,这种计算模型与理论计算结果及实验结果吻合较好,可以准确的预测机匣壁的散射效应对声源传播的影响。

In this paper, a thin-body BEM/FW-H hybrid method is applied to establish numerical model considering the scattering effect of the thin body. This acoustic model can be used to predict acoustic wave propagation include the thin body such as the volute and fan casing. The establishment of the nu- merical model consists of the calculation of the noise source and propagation of the sound wave：firstly, establishing FW-H equation in the frequency domain, and the flow field calculated using computational fluid dynamics method is used to calculate the aerodynamic noise source; and then using a thin body BEM to calculate the scattering effect of the casing. The numerical results are compared with the experi- mental results and the classical duet theory. The results show that the numerical model is validated and can accurately predict the scattering effect of the casing wall on the sound source propagation.