Experimental and numerical study on the flame characteristics and cooling effectiveness of air-cooled flame holder

For high-performance combustion, it needs to meet the requirements of flame stability and heat protection at a wide operating range. In this work, a novel air-cooled flame holding device containing impingement holes and faced film holes, which can achieve flame stabilization and reduce wall temperature. The cooling air flows out and forms vortices attaching on the back wall, functioning as a thickened film that reduces heat transfer and control the distance between the flame and the back wall. The novel composite cooling scheme worked effectively at reaction state and achieved an almost 20% reduction of wall temperature, and the cooling effect of the 30-deg faced film hole was much better than that of the 60-deg faced film hole. Flame stabilization was influenced by the increasing mass rate of cooling air. The oversize distance of flame stabilizing zone and back wall easily caused flame instability even blow-off. 0.3% and 0.5% mass rate of cooling air were enough to achieve flame stabilization and work effectively to decrease wall temperature. The novel air-cooled flame holder saw both flame stability and cooling effectiveness. Because of its compact design and resistance to thermal ablation, it can be of great importance for an advanced burner. (C) 2020 Published by Elsevier Ltd.