电磁声换能器的辐射声场研究

The radiated sound field of electromagnetic acoustic transducer

分析了一种圆环形螺线圈、垂直偏置磁场结构的电磁声探头在非铁磁性介质铝中的辐射声场特性。首先根据电磁感应原理对探头进行了物理和数学建模,将表面力源近似成水平和竖直分布的两种,且水平分量远大于竖直分量,推导出该种力源产生的声场的理论解析解。分别数值计算出了横波和纵波的切向和法向指向性,并和实验结果进行对比。实验结果和理论计算符合较好,为此种结构的电磁声换能器的实际工程应用提供了理论依据。

The radiated sound field produced within a non-ferromagnetic aluminum by an electromagnetic acoustic transducer that had circle-spiral coil and vertical bias magnetic field was studied. First, the physical and mathematical model was established according to the principle of electromagnetic induction, then the surface force source was decomposed approximately into large horizontal and small vertical components, and the theoretically analytical solution of sound field produced by that force source model was formulated. Finally, the tangential and normal directivity pattern of shear wave and longitudinal wave were calculated numerically and compared with experimental results. The experimental results conform well to the theoretical prediction, which provides theoretical basis for the engineering application of this kind of electromagnetic acoustic transducer.