Experimental investigation of ethanol leakage and combustion characteristics on concrete pavements
To study the combustion and spreading behaviors of ethanol spill fires,an experimental platform specifically designed for liquid fuel spill fires was set up.A series of tests on ethanol spill fires were conducted under various leakage rates,both for ignition and non-ignition scenarios.The characteristic parameters,e.g.,diffusion diameter,ethanol thickness,flame temperature,and unit area burning rate were measured and analyzed.The findings indicate that liquid fuel spill fires can be categorized into two stages based on the correlation between leakage rate and combustion rate:the combustion spreading stage and the quasi-steady combustion stage.In the spreading combustion stage,the diameter of the liquid fuel spread under ignition conditions is approximately 87％of that under non-ignition conditions at the same moment.The results demonstrate that both the diffusion diameter and flame temperature exhibit an upward trend as the liquid fuel leakage rate increases within the range of 40-80 mL/min.Notably,when the leakage rate reaches 80 mL/min,the peak flame temperature reaches its maximum,measuring approximately 860 ℃.Furthermore,as the leakage rate increases,the vertical temperature gradient of the flame becomes more pronounced.This leads to a stronger influence of thermal radiation and convection from the flame.Consequently,the velocity of the airflow around the fire source is accelerated,thereby enhancing the air entrainment capacity.A theoretical model has been developed to predict the diffusion diameter in both the spreading combustion stage and quasi-steady combustion stage of spill fires.The experimental results have been well described by physically based models,demonstrating the accuracy of these correlations.Moreover,in this experiment,it was observed that the burning rate of liquid fuel spill fires per unit area is approximately 68％of that in pool fires.There are primarily two reasons for this phenomenon:firstly,there is a certain amount of heat loss during the flow process due to the heat exchange between the liquid fuel and the concrete floor;secondly,in the combustion process of pool fires,the flame consistently exerts a heating radiation effect on the pool,whereas the heating radiation effect on spill fires is comparatively weaker.
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