波数空间中活塞辐射体近场声压分布的计算及测试

在近场范围内,声源在任何平面上的声场都可以通过平面传播波和倏逝波的叠加来得到。以圆形活塞为例,在波数空间中利用角谱法求得其辐射声场的传播波和倏逝波的分布。借助数值分析方法,对圆形活塞声源声轴线上的声压进行计算,得到相应的近场声压分布曲线。由角谱法计算得到的近远场分界点与点源组合法所得结果一致。对不同声源半径时,不同辐射频率下的声压分布曲线进行比较,得出了近场声压的变化规律。阶梯圆盘在辐射理论上应等于对应圆形活塞的辐射。对设计的阶梯圆盘的轴向声压进行了测试,实验测试结果与理论计算结果基本吻合。

Calculation and test of the near-field sound pressure distribution of piston radiator in wavenumber space

The sound field on any plane near a sound source can be regarded as the superposition of a plane propagation wave and an evanescent wave. Taking a circular piston as an example, the distributions of the propagation wave and the evanescent wave of the radiated sound field are obtained by using the angular spectrum method. The sound pressure on the sound axis of a circular piston is calculated by using numerical analysis method, and the corresponding near-field sound pressure distribution curve is obtained. The dividing position between near field and far field obtained by the angular spectrum method is consistent with the one obtained by the point source combination method. By comparing the sound pressure distribution curves of the pistons with different radii at different radiation frequencies, the variation law of near-field sound pressure is obtained. The radiation field of the stepped circular plate should be equal to the one of the corresponding circular piston theoretically. In this paper, the axial sound pressure of the designed stepped circular plate is measured, and the experimental results are basically in agreement with the theoretical results.