非等温空腔法确定固体材料的比辐射率

本文讨论一种确定固体材料比辐射率的方法。在被测材料的表面开一个圆柱形空腔,并在其背面均匀加热。联立求解腔壁的辐射换热和体内的热传导方程,求得温度场分布和腔底的有效辐射。结果表明,腔底的有效辐射是比辐射率、腔深和半径之比以及一个表示温度梯度的参数的函数。文中讨论了能量辐射和光子辐射两种情况。在实验中,用热象仪测量材料表面和腔底的有效辐射。由理论分析结果和实验测定的有效辐射,求得材料的比辐射率。

Non-isothermal Cavity Methods for Determining the Emittance of Solids

A method is presented for determining the emittance of hot solids. The finite length circular cylindrical cavity may be visualized as a hole drilled into the exposed face of a solid with the solid being heated uniformly from behind. The results are obtained by solving the coupled problems of radiant transport in the cavity and two-demensional heat conduction in the solid that bounds the cavity. From the solutions, results for the radiant flux leaving the base face of the cavity are presented as a function of the emittance, of the depth-radius ratio of the cavity, and of a temperature gradiant parameter. Both thermal radiation and photon radiaton are studied. In the experimemts, the emittance of both the exposed face and the base face of the cavity are measured with AGA-780 thermovision. The emittance of the solid is found by combining the experiments with the theoretical analysis.