阶梯状声扩散体形体优化方法

Stepped sound diffuser’s shape optimization

应用时域有限差分法计算阶梯状声扩散体扩散系数,结合免疫遗传算法分别对周期排布的六阶和十二阶阶梯状声扩散体的形体进行优化。首先,验证了时域有限差分法计算声场的有效性,之后采用两种方式进行优化设计:第一种是直接对多周期重复排布的扩散体形体进行优化;第二种首先对单周期扩散体形体进行优化,再将该扩散体重复周期排布。结果显示:第一种优化方式能获得扩散性能更优的周期排布的扩散体。单周期扩散性能最优的扩散体重复一定周期后,其性能不会保持最优,相反,扩散性能并非最优的单周期扩散体重复一定周期后的扩散性能却优于前者;扩散体总长度一定条件下,增加扩散体的阶次、降低重复周期数,可有效提升扩散体的扩散性能。因此,直接对多周期重复排布的高阶次扩散体形体进行优化,能够获得扩散性能最优的周期重复排布的扩散体。

The Finite Difference Time Domain(FDTD) method applied in sound scattering prediction was validated firstly,then the shape of 6-and 12-order-stepped sound diffusers consisted of multiple periods were optimized respectively using hybrid method combined FDTD with immune genetic algorithm.Two optimization ways were used in the present study for comparison.One is to directly optimize the shape of diffusers consisted of repeated periods,and the other is to conduct the optimization for single period diffuser before period repetition.The results show diffusers with better diffusion performance can be obtained in the first optimization way;the single period diffuser with the optimal shape will not remain the best diffusion performance when repeated for some periods,on the contrary,some with non-optimal shape for a single period could achieve better diffusion performance than the former when certain periods were repeated.The diffusion performance would be improved when increasing diffuser’s order and decreasing diffuser’s repeat periods under the same overall diffuser’s width condition.It was concluded that the way to achieve best diffusion performance for periodic diffusers was optimizing shape of periodic diffusers with higher order directly.