聚焦型热声转换装置的特性

设计了一种新型的聚焦型热声转换装置，主要由加热层、绝缘层和储热层三层结构构成。当加热层输入交变电信号时，由于焦耳热效应及各层材料的热力学特性，其表面附近区域内气体压力产生交变的振荡，加热层的凹球表面会使产生的声波在某一区域聚焦。通过对装置进行数值模拟与实验研究，得出声波聚焦区域及聚焦点声压强度随声波频率的变化情况。装置可作为一种新型的声学聚焦换能装置，工作频率涉及可听及超声频域，无共振，无运动部件。这一研究具有一定的应用价值。

Characteristics of a Focusing-type Thermo-acoustic Transducer

A new type of focusing thermo-acoustic transducer, which is composed of a heating surface, an insulation layer and a thermal storage substrate, was designed. When alternative voltage signal is input to the heating surface, due to the Joule heating effect and thermodynamic characteristic of material in each layer, the pressure of the air near the heating surface will oscillate, and the radiation sound will be focused in a small region by the concave spherically heating surface. Through numerical simulation and experimental study of the device, the variations of the focusing area and the sound pressure at the focusing point with acoustic frequency were given. The device can be used as a new type of acoustic-focusing and energy-exchanging device. It can radiate sound in the audible and ultrasonic regions without resonances and moving components. This study has a practical significance and an application prospect.