Study on the subsurface flow induced by flame spread over aviation kerosene

Experiments were conducted to investigate the characteristics of the subsurface flow induced by flame spread over aviation kerosene using schlieren photography, particle image velocimetry, infrared camera, and thermocouples. Experimental results show that the structure of the subsurface flow for flame spread over aviation kerosene is different from that for alcohols. For pulsating flame spread regime, there is always a fully-developed vortex with a thermal penetration depth of about 8-10 mm preceding the flame front, and a new one appears periodically under the flame front when the flame starts to spread at crawling velocity. The initial pool temperature has a great effect on the length of the subsurface flow but has no obvious effect on the penetration depth of the fully-developed vortex. Great temperature gradient was detected both along and normal to oil surface ahead of the flame. The rate of the subsurface flow increases with an increase of the initial pool temperature. The theoretic calculations based on the surface tension effect overestimate the experimental values for high initial pool temperature, and the reasons for the difference were analyzed.