【摘要】 本文将边界元法应用于具有平均流的管道及膨胀腔声学特性的三维分析,获得了具的平均流介质中声传播问题的边界积分方程和基本解。采用九节点二次等参单元离散边界表面并对物理量插值,对奇异积分采用极坐标变换法和间接法联合来消除奇异性,在棱边角点处区分不同方向的质点振速。文中对有无平均流时直管的四极参数及膨胀腔的传递损失进行了计算,并与一维理论及其它方法计算结果进行了比较。更多还原

【Abstract】 The boundary element method is applied to analyse three-dimensional acoustic characteristics of ducts and expansion chambers with mean flow, The boundary integral equation and fundamental solution of wave propagation in the presence of mean flow have been obtaind. The nine nodes quadratic isoparametric elements areused to discretize boundary surface. The polar coordinate transformation method and indirect method are jointly used to treat singular integration problem, the different partical vibrating velocities are supposed at points of corner, the four-pole parameters of a stright duct and transmission loss of an expansion chamber with and without mean flow have been calculated and compared with results obtained by means of one-dimentional theory and other methods.更多还原