【摘要】 用蒙特卡罗法计算了圆柱型空腔底面与管内壁面单元之间的辐射传递系数,研究了底面为黑体表面、管内壁面为等温灰体、漫发射、漫反射时,管内壁发射率、管长与半径比的变化对管口表面定向发射率的影响,结果表明:管长与半径比增加,管口表面定向发射率极值点向小角度的天顶角方向移动,管长与半径比超过30,管口表面最大定向发射率对应天顶角<2°;管内壁发射率为变量时,距离管出口1倍管内直径处的发射率对管口表面最大定向发射率的影响较大;管内壁的发射率越小,管口表面定向辐射集中特性越好.更多还原

【Abstract】 To obtain directional properties of radiant energy streaming from an isothermal radiant cylindrical cavity, a Monte Carlo method solving the RD’s value between cavity wall elements was presented. The calculations of equivalent directional emittance of cavities were performed for black body surface for undersurface and gray, diffusely emitting and reflecting side surface for tube, while the parameters that were varied includesed the emissivity of the side wall, the depth-to-radius ratios. Results of the analysis illustrate the polar angle of maximum equivalent directional emissivity decreases with the increase of the depth-to-radius ratio, and the value of equivalent directional emissivity of small polar angle increases with increasing the depth-to-radius ratio. When the radio of depth-to-radius is bigger than 30, the polar angle corresponding to maximum equivalent directional emissivity is little than(or equal to) 2 degrees. The effect of inner wall emissivity of the elements between aperture and 1 multiple of inner diameter of tube is more marked when the side wall emissivity of tube is variable, and the directionality of radiation of cavity is increased at lower values of the side wall emissivity.更多还原