Simulation Of Burning Rate In The Middle Scale Pool Fire Based On Coupling Of Gas And Liquid

Oil fires often cause serious casualties and property losses.It is particularly important to grasp the development trend of fire in time and accurately predict it.There are two main types of oil fires: storage tank fires and flowing fires.There have been many studies on these two types of fires,but there are few literatures on the development and change of flames and the instantaneous prediction of the burning rate.In order to improve the existing numerical model for predicting the burning rate of pool fires,this paper proposes a fully coupled three-dimensional numerical model,which takes into account the fuel surface and internal flow caused by non-uniform thermal feedback,and directly solves it.Based on the Open FOAM platform,large eddy simulation(LES)is used to numerically solve the gas-phase pool fire.The fuel area is solved by establishing an incompressible laminar flow control equation to solve its flow process,and Boussinesq approximation is used.The physical parameters except density are set to constant values.At the gas-liquid interface,the two-way coupling conjugate heat transfer method is used to solve the heat transfer between the two phases,and the evaporation model based on the "thin layer theory" is used to solve the mass transfer process.Among them,the global characteristic length is used to calculate the mass transfer coefficient in the evaporation model.The validity and accuracy of the numerical model proposed in this paper are verified through thin-layer fuel pool fire experiment and thick-layer fuel pool fire experiment.The results show that the pool fire prediction result obtained by using the predicted combustion rate is more accurate than the result obtained by using the fixed combustion rate;the three-dimensional gas-liquid coupling model improves the shortcomings of the one-dimensional heat transfer model,and can accurately predict the heat transfer and the existence of anti-vortex inside the fuel,and then accurately predict the combustion rate;the liquid phase flow movement has a certain influence on the combustion rate.In the 0.3 m diameter thick methanol pool fire,ignoring the convection movement will cause The early combustion rate rises too fast;in the 1.0 m diameter thick methanol pool fire and the 0.3 m diameter thin heptane pool fire,ignoring the Marangoni flow will cause the burning rate to rise too fast.And,this paper studies the grid resolution needed to meet the calculation requirements.