Experimental investigation of a post-combustion pool fire phenomenon due to the spray-wall interaction under DI engine-like cold-start conditions

Spray-wall interactions (SWI) have remained nowadays as an active area of research and the complex multi-physical field processes between the spray and the wall are still not well understood. In this study, a post-combustion pool fire phenomenon due to the SWI was found by optical diagnostic techniques: pool fire appeared near the stagnation point after spray combustion. The spray combustion and pool fire are not continuous. This abnormal combustion characteristic under low ambient temperature conditions (680–720 K) was investigated and the effect of ambient temperature on the macroscopic characteristics of pool fires was quantified and analyzed. The results show that the wall-attached fuel film will be re-ignited and continue to combust for a longer period after the impingement spray combustion. The appearance moment, dwell time, fire duration, and macroscopic characteristics of this post-combustion pool fire are non-monotonic as a function of the ambient temperature. When the ambient temperature is 700 K, the post-combustion pool fire appears earliest, the dwell time is the smallest, and the pool fire duration, flame length, and flame height of the pool fire are the largest. This is mainly dominated by the gas temperature around the wall-attached fuel film and fuel film mass.