Radiant emission from baffled conical cavities

Abstract

An analysis is made to determine how the radiant energy streaming from an isothermal-wall conical cavity is affected by a baffle that partially obstructs the cavity opening. Consideration is given both to baffles that are maintained at the same temperature as the cavity wall (emitting baffles) and to baffles that are cooled to a temperature well below that of the wall (non-emitting baffles). The cone-apex angle and the emissivity of the cavity wall are varied parametrically. The results are obtained by employing a newly devised Monte Carlo method, the application of which is described in detail. The presentation of results is made in terms of the apparent emissivity, which is the ratio of the radiant energy actually streaming from the cavity to the radiant energy emitted by a black surface whose size is the same as the baffle aperture. It is found that the apparent emissivity increases as more and more of the cavity opening is blocked by the baffle. The increases of apparent emissivity are greater when the baffle is emitting than when the baffle is non-emitting.