变截面圆柱形空腔覆盖层吸声系数的二维近似解

具有空腔周期性排列的粘弹性结构在水声工程中有着广泛的应用.将包含变截面圆柱形空腔周期性排列的吸声覆盖层的一个单元进行分段近似成多层圆柱管结构,并应用子域分割法在分段的接合界面处满足平均轴向位移和平均轴向应力连续,给出了变截面圆柱形空腔吸声覆盖层吸声系数的二维近似解.分析了高阶传播波和分段层数对吸声系数的影响,比较了不同空腔形状对覆盖层吸声性能的影响.研究结果表明,在一定频率范围内,主要是最低阶传播模式对吸声性能起作用,喇叭型空腔结构较圆柱型空腔结构吸声覆盖层的吸声性能更加优良.在覆盖层设计中,空腔的形状应有一个优化的过程.

Analysis of acoustic characteristics of anechoic coating containing varying sectional cylindrical cavity

A unit cell of anechoic coating containing varying sectional cylindrical cavity is approximated as the structure of layered cylindrical tubes.By applying the subregion dividing method,the continuum condition of average axial stress and displacement is satisfied at each annular area of the cross-section.Then a two-dimensional approximate analytical solution of acoustic characteristics of anechoic coating is developed at normal incidence plane wave.The influences of higher propagation modes to acoustics characteristics are analyzed.The absorption performance of anechoic coating with various shapes of cavity is compared.The results show that the lowest order mode plays a main role for acoustic characteristics.The absorption performance of anechoic coating containing cylindrical cavity with horn shape is better than that containing uniform cylindrical cavity.The shape of cavity should be optimized in the design of anechoic coating.