Study And Analysis On The Smoke Diffusion Mechanism Of Highway Tunnel Dual Fire Source Fire

In recent years,highway tunnels have developed rapidly,and fire accidents often happen at home and abroad,which bring threats to people’s lives and property.Vehicle collision is an important cause of highway tunnel accidents.Tunnel fires caused by multiple vehicles burning simultaneously also occur from time to time,which is because of continuous collisions,and Multi-fire tunnel fire will bring greater harm to the safe operation of the tunnel.Since scholars at home and abroad have little research on multi-fire tunnel fires,in order to explore the smoke movement of multi-fire tunnel fires,this paper studies the smoke diffusion of the double fire source fire in the highway tunnel.First,in this paper,FDS software is used as a research tool to build a tunnel model based on the Phoenix Mountain Tunnel.The simulation conditions such as fire source power,longitudinal wind speed,and distance between fire sources are determined,and 15 working conditions are set for simulation.Then,based on the simulation results,the smoke movement of the double fire source fire in the highway tunnel was analyzed,including: the simulation of single-fire source tunnel fires with 30 MW and 60 MW fire sources,and comparative analysis of the change law of temperature field and smoke field under the conditions of no longitudinal wind speed,small longitudinal wind speed and critical wind speed,the influence of fire on tunnel structure and rescue evacuation;simulate the fire of double fire source tunnel with fire source spacing of 3m,6m and 9m respectively,and comparatively analyze the change of temperature field and smoke field under different longitudinal wind speeds,get the impact of the fire on the tunnel structure and evacuation of personnel.In addition,in this paper,the critical wind speed of the double fire source tunnel fire is studied in depth.In order to obtain the prediction formula for the critical wind speed of the double fire source tunnel,firstly,the dimensionless analysis method is used to obtain the dimensionless function relationship between the critical wind speed and the upstream fire source power,the power ratio between the fire sources,and the fire source spacing,then set the working conditions,and simulate to get the data,and then the prediction formula of critical wind speed is derived from the data.At last,in this paper,the prediction formula of the maximum distance is explored.Firstly,the dimensionless function relationship between the maximum distance and the power of the upstream fire source and the power ratio between the fire sources is analyzed,and then the working conditions are simulated to obtain the data.The prediction formula for the maximum distance is combined.Through the above research,the reference available safety time at 10 m upstream of the tunnel under different working conditions of the double fire source fire in the highway tunnel is obtained.The prediction formula of the critical wind speed and the maximum distance of the dual fire source fire in the tunnel is verified,and the prediction result of the formula is relatively accurate.