有源声学结构降噪的物理机制分析

An exploration of physical mechanism in active acoustic structure

有源声学结构是近年来提出的降低结构低频声辐射的有效方案,对其降噪中的物理机制进行分析将为系统优化设计、次级源和误差传感器布放及控制目标选取等关键问题提供直接指导。文中在最小辐射声功率条件下,从控制前后初、次级结构的辐射声功率变化以及声场中声强的分布来阐述降噪中的物理机制,研究结果表明:降噪中的能量转换分为能量抑制、能量吸收及能量反吸收三种机制;对于近场声强分布,有源控制效果主要通过声强幅度抑制和声强方向调整两种机制体现,部分区域的声能量在控制前向远场传递,控制后则流向声源。

Active Acoustic Structure （AAS） proposed in recent years has been viewed as an encouraging approach to actively control sound radiation from vibrating structures. Analyzing the physical mechanism of AAS can offer some guidance to key issues e.g. design optimization, the arrangements of secondary sources and error sensors, and selecting objective function. In this paper, under minimization of the total sound power output, the physical mechanism of noise reduction is investigated by analyzing the sound power output change of primary and secondary structures and the distribution of sound intensity. The results show that there are three mechanisms in active control, which are energy restraint, energy absorption and energy un-absorption. For near field sound intensity distribution, the effect of active control is revealed by amplitude restraint and direction adjusting for sound intensity. Partial acoustic energy which is transferred into far field before control will flow to sound sources after control.