圆环式径向换能器声压分布及其指向性

The analysis of sound pressure distribution and directivity of traffic circle shaped radial transducer

根据圆环式径向换能器的对称性,定性分析了其声压分布性质,提出将辐射面镶在无限幕上并向辐射面的外法线所在的半空间辐射声场的分析模型;根据惠更斯原理,推导了圆环式径向换能器辐射声场远场区的声压分布以及指向性函数;通过MATLAB绘制指向性函数曲线,研究换能器的有效工作段长度、外径以及辐射频率对其指向性的影响。结果表明,当换能器的尺寸一定时,辐射频率增大,指向性增强;当换能器的辐射频率和外径一定时,换能器的有效工作段长度增大,指向性增强;当换能器的辐射频率和有效工作段长度一定时,外径对声场指向性的影响不大。结合有限元分析软件COMSOL Multiphysics,仿真声波在混凝土中的传播,进一步验证了以上结论。

According to the symmetrical characteristic of traffic circle shaped radial transducer, the sound field distribution eradiated by the transducer is qualitatively analyzed. The model basic hypothesis is that the radiated surface of the transducer is embedded in an infinite board and the sound field is eradiated along exterior normal in a half infinite space. The sound pressure and the directivity function in the far field are calculated based on Huygens principle. By means of MATLAB, the directivity function in polar coordinates is derived, and then, the effect of effective working length and outer diameter and frequency of the transducer on the directivity function are assessed. The result shows that for the constant transducer size, the directivity enhances with the increase of frequency. When both radiating frequency and outer diameter are fixed, the directivity enhances with the increase of effective working length. When both radiating frequency and effective working length are fixed, outer diameter has a little effect on the directivity. To verify the relationship between directivity and frequency, COMSOL Multiphysics is used to simulate the propagation of stress wave in concrete.