Study On Combustion Characteristics Of Fire Whirl Under Atmospheric Pressure And Dynamic Pressure Environment

Fire whirls as a fire in a wide range of hazards,destructive a unique phenomenon,often in urban and forest fires.Fire whirl is a kind of chemical reaction accompanied by a spin flow,in the generation of fire whirl will significantly increase the heat release rate of the fire source,and accelerate the combustible combustion rate,resulting in further expansion of the firing range,fire temperature rises sharply,the threat to the safety of people and property is also further escalated.Compared with ordinary buoyancy pool fire,the fire whirl flame height,flame temperature,and other characteristic parameters are significantly higher.After the generation of the fire whirl,the flame will be sucked within a specific range of combustible materials to maintain combustion;in the fire whirl,out of its momentum and heat,easy to produce the "flying fire phenomenon," the formation of a new fire,accelerating the development and spread of fire.The study of the combustion characteristics of the fire whirl can help scientific understanding of its unique formation mechanism,type,and movement pattern,further understanding of the combustion characteristics of the fire whirl,the mechanism and combustion law,and establish the criteria for predicting its formation and movement behavior,which can avoid accidental casualties of personnel,especially the scene fighters,and provide theoretical guidance and data support for the prevention and suppression of fire whirl disasters,and the study has confidence The study has some scientific value and foresight.In this paper,a small-sized four-wall-slit fire whirl experimental platform is built.Under the conditions of atmospheric pressure and steady state,the influence of parameters such as oil basin diameter and air inlet width on the combustion characteristics of the fire whirl is investigated,and the changes of combustion kinetic characteristics such as mass loss rate,flame shape and height,and flame temperature of the fire whirl are investigated;the experiments related to the fire whirl under pressure dynamic conditions are carried out based on the low-pressure chamber,and the trends of flame height,mass loss rate,heat radiation flux,and other characteristic parameters are measured and analyzed to reveal the trends of the fire whirl.In order to reveal the dependence of fire whirl fire behavior on pressure,we measured and analyzed the trends of flame height,mass loss rate,heat radiation flux,and other characteristic parameters.This paper contains the following two main aspects.1.An experimental study of fire whirl combustion characteristics under atmospheric pressure steady-state conditions was carried out using a small-sized four-wall-slit fire whirl device.The parameters of mass loss rate,flame height and morphology,flame center axis temperature,axial flow field,and axial flame heat radiation flux were measured for the fire whirl steady-state conditions.The dependence of these characteristic parameters on the oil basin diameter and air inlet width was investigated.The linear relationship between flame height and dimensionless Peclet number is analyzed,and the theoretical model of dimensionless flame height is modified.The relationships between the flame center axis temperature,slit axial flow field,axial flame heat radiation flux,and dimensionless height are determined.Moreover,the semi-empirical formula between mass flux and dimensionless inlet air velocity was proposed.2.The study of the trend of the combustion characteristics of the fire whirl under dynamic pressure was carried out.The analysis of the mass loss rate of fire whirl under dynamic pressure was carried out,the variation law of mass flux with ambient pressure was explored,and the dimensionless analysis between combustion rate and ambient pressure and inlet width was carried out based on Grashof number;the measurement and analysis of thermal radiation flux of fire whirl were carried out,and the empirical equation between dimensionless thermal radiation flux and ambient pressure was established.The "critical width" in developing the fire whirl was discussed.Figure [32] table [3] reference [92]...