弹性球壳声衍射对矢量传感器测量影响

Influences of sound diffraction by elastic spherical shell on acoustic vector sensor measurement

声矢量传感器由传统的无指向性声压传感器和偶极子指向性质点振速传感器组成,被应用于水声测量和探测领域,但作为水声测量设备它会受到安装载体衍射声场的影响,使其接收声场失真和指向性发生畸变.以实际应用需求为背景,从理论上分析了平面声波在弹性球壳上的衍射声压场和振速场;采用薄壁球壳机械阻抗近似公式,计算了球壳声衍射对矢量传感器声场测量和指向性的影响.根据共振散射理论,弹性球壳衍射声场的共振项与壳体的机械阻抗和辐射阻抗有关,而其背景项与刚性球和绝对软球的声衍射有关.计算和分析结果表明,在球壳散射声场的共振项频率处,矢量传感器的接收声场严重失真,且其指向性图变得复杂;另外,它们也与声波的入射方向和距离有关.这些结果为利用矢量传感器进行水声测量和探测提供基本的物理基础.

An acoustic： vector sensor （AVS） is combined with a traditional omni directional sound pressure sensor and dipole directional particle velocity sensor, which is applied to underwater acoustic measurement and acoustic detection. Because of the sound diffraction by the AVS carrier, the receiving sound field and directivity of AVS are not the ,same as that in the free sound field. Here, the sound pressure field and particle velocity field of sound diffraction by an elastic spherical shell are studied theoretically. The influences of sound diffraction by a spherical shell on the measurement results and directivity of AVS were calculated by using the approximate equation of mechanical impedances of the thin spherical shell. According to the resonance scattering theory, the sound diffraction field is composed of the resonance component and the background component, which the former depends on the mechanical impedance and the acoustic impedance of the spherical shell, but the latter depends on the sound diffraction of the rigid sphere and the soft sphere. Computer simulation and analysis show that the receiving sound field and directivity diagram of AVS are seriously distorted at the resonance frequency, and they also are related to the distance and angle of incident plane wave.