Study On Influence Of Tunnel Transect And Fuel Quality On Stability Of Smoke

Tunnel is a kind of building form in which human beings use underground space to meet their own developed needs.With the rapid development of China’s economy,the process of urbanization is increasingly accelerating.The rapid development of transportation industry has brought great pressure to road traffic.Humans are also worried about the frequency of fire accidents while enjoying the convenience of tunnels.This paper mainly uses scale simulation experiment and numerical simulation method to study the influence of different fuel properties and tunnel section width on tunnel fire smoke.In the section of scale reduction experiment,the paper studied on the combustion of three common car fuel include diesel,gasoline,ethanol gasoline by a 1:10 small-scale model test bench and thermocouple devices.The experimental results show that different fuel fires have great influence on flue gas stability.Diesel has the highest molecular weight,the slowest combustion rate and the lowest fire power,its smoke stratification effect is not as strong as the other two fuels,but the time of the relative stability is maintained longer.Gasoline and ethanol gasoline are similar,and both burn violently,and the effect of smoke stratification is about 30% higher than that of diesel,but the time to maintain a relatively stable state is about 50% shorter than diesel combustion.In the numerical simulation section,for different numbers of lanes,three kinds of tunnels with different widths and 150 meters long were built.Studying flue gas in tunnel by changing the wind speed in different longitudinal directions under fixed fire source power.It is found that the increase of tunnel section width at the same wind speed is beneficial to the smoke stratification,and the maximum wind speed to allow safe escape for people downstream of the fire source also increases.After preliminary study,the critical value of the stratification intensity is 0.88,when the value is below 0.88,the smoke stratification is seriously damaged,and the fire personnel cannot escape safely.At the same time,we found that flue gas fluctuations become more intense when wall fire occurs by compared experiments,but it doesn’t affect safety.