摘要
双向反射分布函数BRDF真实描述了实际表面的反射特性,本文用BRDF表面代替传统的漫反射和镜反射表面研究了富氧燃烧过程中壁面对非灰气体辐射传热的影响。本文选取刚玉板(A1203)作为BRDF壁面,BRDF值使用NIMS-III BRDF测量系统测得,而且测量值用简化五参数模型进行了很好的拟合。比较漫反射表面和BRDF表面两种不同边界条件下的热辐射特性发现BRDF表面对热辐射有较大影响,尤其在更小的板间距、更高的表面和气体温度、含有较低浓度水蒸气时。
The BRDF(Bidirectional Reflectance Distribution Function) surface truly described the reflection characteristics of real surface, thus is introduced into the calculation of non-grey gas radiative heat transfer in oxy-fuel combustion. This paper chooses a Al_2O_3 plate as the boundary surface, the Al_2O_3 BRDF is measured by the NIMS-III BRDF measure system. A simplified five-parameter model is applied to fit the measured BRDF, and result shows it fit the experimental BRDF value well. The thermal radiative characteristics under two different boundary conditions were compared: both the radiative source and the radiative heat flux exist difference between diffuse and BRDF surface, the effect of BRDF surface on radiative heat transfer is more obvious at smaller separation distances, higher surface and gas temperature, when containing less H_2O.
引文
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