Xia Xinlin

Thermal emission of a disc body of semitransparent material

By introducing the concept of radiosity intensity to diffuse surfaces, the ray tracing method is improved to analyze the thermal emission of a disc body of gray semitransparent material. The two plane surfaces of the disc body are both specularly reflecting, and the flank surface is either diffusely reflecting or specularly reflecting. The apparent thermal emission from one plane surface is investigated with considering the influences of the characteristic optical thickness, the dimensionless radius, the refractive index of the material and the reflecting characteristics of the flank surface. The directional and hemispherical emissions show considerable differences under different reflecting characteristics of the flank surface. Moreover, in some cases, the emission not only varies with the viewing direction but also with the apparent emitting position on the plane surface. Some interesting results are presented and discussed.

Three dimensional transient coupled radiative-conductive heat transfer in cylinders filled with semi-transparent media with complicated surface characteristics

Using the Control Volume and the Discrete Transfer (DT) methods incorporating the Spectral Band Model, the transient coupled radiative-conductive heat transfer is investigated in cylinders filled with semi-transparent media with both opaque and semi-transparent surfaces. This is a three dimensional problem with nonlinear boundary conditions of the second and third kinds. The temperature field in the optical window of a space camera is calculated with complicated boundary conditions. By comparing with the zone and the improved Monte-Carlo methods, the reliability and calculating precision of this method are shown.Using the Control Volume and the Discrete Transfer (DT) methods incorporating the Spectral Band Model, the transient coupled radiative-conductive heat transfer is investigated in cylinders filled with semi-transparent media with both opaque and semi-transparent surfaces. This is a three dimensional problem with nonlinear boundary conditions of the second and third kinds. The temperature field in the optical window of a space camera is calculated with complicated boundary conditions. By comparing with the zone and the improved Monte-Carlo methods, the reliability and calculating precision of this method are shown.