超声吸收体边界条件的分析

The analysis of absorber's boundary condition

超声吸收体的边界条件分析对于求解超声吸收体表面温升与入射波声强的函数关系至关重要。通过分析在超声吸收体与水和与空气界面处超声辐照的物理过程,分别得到超声吸收体与水界面处的平均传热系数与焦点声强之间的函数关系式和超声吸收体与空气界面处的复合传热表面系数与温差的函数关系式。通过仿真分析了不同条件下两个界面处的传热系数对超声吸收体与空气界面温升的影响。实验结果表明,当辐照时间较短时,对于超声吸收体与空气界面的温度变化,超声吸收体与水界面可以认为是一个无限远且温度恒定的边界,超声吸收体与空气界面可以认为是一个符合第一类边界条件的连续热传导。

The analysis of boundary condition of acoustic absorber is important for solving the functional relationship between the surface temperature and incident sound intensity. In this paper, the functional relationships between average heat transfer coefficient and focus intensity at the absorber-water interface as well as between composite surface heat transfer coefficient and temperature elevation at the absorber-air interface are established by the analysis of irradiation process. The surface temperature elevation at the absorber-air interface, which is affected by heat transfer coefficients at the two interfaces, is analyzed by simulation. The results show that the absorber-water interface can be regarded as an infinite far and constant temperature boundary and the absorber-air interface can be considered as a continuous heat conduction in accordance with the first class boundary condition when the irradiation time is short.