基于边界元法的二维变截面管道内部噪声传播分析

利用二维边界元计算程序,分别研究了扩张和收缩两种变截面管道内部噪声传播规律。结果表明:采用二次单元边界元方法进行计算时,单元尺寸小于1/6波长可使计算相对误差达到1%以下;变截面腔室长度为半波长整数倍时,变截面腔室前后的声压分布相同,且此时的传递损失最小;变截面管道的收缩比越小或者扩张比越大,对应的传递损失也越大,其消声特性越强;变截面管道的起始变化点对于消声特性没有影响,但透射声压会随之周期性产生峰值点。

Investigation of noise propagation in two-dimensional varying cross section pipes by the boundary element method

Noise propagation in expansion and contraction varying cross section pipes was studied in this paper by two-dimensional boundary element method(BEM) codes.Simulation results showed that calculation error can be reduced below 1%,if the biggest element size is smaller than 1/6 of the wavelength for quadratic elements.When the length of the varying cross section chamber is equal to a whole-number multiple of half wavelength,the sound pressure distributions on the upstream and downstream sides of the chamber are identical and the transmission loss reaches to minimum.With decreasing contraction ratio or increasing expansion ratio,the transmission loss increases and the noise attenuation effect becomes better.The starting position of the varying cross section pipe has no influence on the noise attenuation effect.However,peaks of transmission sound pressure appear periodically at distances relevant to a whole-number multiple of half wavelength.