Experimental And Model Study On Burning Rate Of Flammable Liquid Spill Fire

During the storage and transportation of flammable liquid fuels,the failure of the storage and transportation container usually leads to the leakage of the fuel.The leaking fuel flows around under the action of gravity.Once ignited,a spill fire is formed.In the actual leakage fire accident,the existence of the ground slope tends to accelerate the expansion of the spill fire and form a larger burning area,which makes the ground slope an important factor affecting the burning rate of the spill fire.In this paper,the fireproof glass is used as the free spread surface of the leaking fuel,and the experimental research on the spill fire under different slopes and different discharge rates is carried out.The experimental ignition method is delayed ignition.In the experiment,the non-contact measurement method was used for the first time to measure the steady fuel thickness of the spill fire under different slopes and different discharge rates,which can be used to establish the theoretical model of the burning rate of the spill fire.The results show that when the slope of the substrate surface increases from 0° to 0.4°,the steady fuel thickness of spill fire decreased from 0.60 mm to0.43 mm.Under the same slope,the steady fuel thickness does not change significantly with the change of the discharge rate.This shows that the thickness of the fuel thickness of the spill fire is not sensitive to the discharge rate.According to the time-varying spread and burning area,the delayed ignition spill fire is divided into five burning phases:(I)spread of the spill fuel,(II)shrinkage of the burning zone,(III)quasi-steady burning,(IV)maintenance after discharge time,(V)extinguishment phase.In the steady burning phase,the burning rate of a spill fire is the ratio of the discharge rate to the burning area.The experimental results show that: in the equivalent diameter range of0.15 m-0.35 m,the steady burning rate of spill fire does not change much with the increase of the discharge rate for the same slope;for the same discharge rate,the steady burning rate decreases with the increase of the slope.For a spill fire with an equivalent diameter of 0.15 m to 0.35 m,the total heat feedback received by the fuel layer is dominated by convective heat,of which more than 87.97% of the heat feedback is convective heat.This suggests that the equivalent diameters in the spill fires describing the transition from convection control to radiation control are larger than those in pool fires.The radiant heat feedback amount absorbed by the spill fire fuel layer was calculated using the experimental measurement results of the fuel thickness of the spill fire,and the theoretical model of the burning rate of the spill fire was established.In this paper,the experiment of n-heptane spill fire on the glass surface under different slopes is carried out.A method for measuring the thickness of the burning fuel of the spill fire is proposed,which helps establish the burning rate model of the spill fire.