Combustion Characteristics And Spread Rules Of Diesel Oil Pool Fire In Ventilation Environment

With the rapid development of economics, the risk of fire has been highlighted. On account of the rapid spread velocity of fire and the serious difficulty in fire suppression, the combustible liquid fire will cause serious economic losses and a large number of casualties. The more serious scenario is the mechanical ventilation situation in narrow and long spaces such as tunnels or the complex natural ventilation surroundings in open oil tank zones, which will result in special rules in combustion characteristics and spread rules of fire. Therefore, It has great significance to prevent fire and reduce fire loss on the base of the research on the rule of combustion and development of fire in ventilation surroundings. First of all, a experimental model of 6m×1.5m×2m is set up in this paper, the diesel oil pool fire experiments with single and double oil basins are taken in various ventilation conditions. And through the test and comparison of the measuring parameters near the fire, such as temperature and radiation heat flux, the combustion characteristics and fire spread rules of diesel oil pool fire are analyzed by adopting the combination of experiment and theory analysis method.First of all, the 0.25m×0.20m×0.05m single oil basin pool fire experiments by using the mixed liquid of 100ml diesel oil and 100ml water as fuel in the model of the experiment model with natural ventilation. The researches show that all parameters of the oil pool fire are reaching the maximum value in vigorous stage. In the burning exuberant stage of diesel oil pool fire, the liquid continuous in generating a lot of bubbles, sparks flew off in all directions from flame, boil over comes and then splash for many times, both the temperature and the radiant heat flux reached maximum in continuous splash. Then, the experiments are taken respectively by changing the fuel oil-water ratio(2:1,1:1,2:5) with natural ventilation. The result indicates that with the water content reduced, the burning rate of the flammable liquid increases, the intensity of the flame reduces, the development of the whole combustion process becomes slow, and frequency and intensity of splashing reduce.Further more, the velocity of the mechanical ventilation is changed to analyze the effect of mechanical ventilation on the combustion characteristics of oil pool fire. The result shows that mechanical ventilation prompted the increase of heat exchange between fire and air, the discharge of mass hot smoke make the temperature of flame and hot smoke layer reduce, thermal feedback on the oil surface that come from flame and hot smoke layer will decrease, so that the progress of the combustion process is inhibited, the fire is hard to get exuberant stage, but will stay in this stage for longer.Finally, the ignition experiments under the different spacing and mechanical ventilation conditions are taken by using two burning plates whose size are 0.25m×0.2cm×0.05m and 0.16m×0.08m×0.015m separately. Experiment results indicate that with the increase of the mechanical ventilation velocity, the probability of being ignited of the neighbor oil plate is increased; the fire safety distance between the two oil plates is reduced.In the beginning stage and the growth stage, the mechanical ventilation can be increased to delay the development of the fire. When fire comes to exuberant stage, the mechanical ventilation power should be reduced appropriately to control the spread of the fire.