闪光法测量半透明材料热扩散率的理论研究

建立了闪光法测量半透明材料热扩散率的一维瞬态导热-辐射耦合换热数学模型,采用基于控制容积的离散坐标法分析求解激光脉冲在半透明材料内的温度响应,并与由热四端网络法得到的半解析解进行了对比和验证.研究结果表明:两种计算方法在各种计算条件下得到的结果吻合很好.数值方法更灵活,可以处理物性非线性问题,但计算时间较长;半解析法的计算速度非常快,但只能处理常物性问题.此外,本文对试样吸收系数、辐射边界、厚度及试样表面的热损失等因素对温度响应的影响进行了对比分析.

Theoretical study on thermal diffusivity measurement of semi-transparent materials by the flash method

A transient one-dimensional coupled conduction-radiation heat transfer model was developed for thermal diffusivity measurement of semi-transparent materials by the flash method. On the basis of the control volume method, the discrete ordinate method (DOM) was used to solve the radiation heat transfer equation of the model. It showed that the numerical results were agreed well with those by the thermal quadrupoles method (TQM). DOM was a little bit time-consuming but was available for a non-linear physical property problem. Only a constant physical property problem can TQM solved, although it is faster than DOM. The sample's backside temperature response was analyzed for various sample thickness, absorption coefficient, radiative boundary condition and heat loss.