Study on Fire Smoke Control by Air Curtains in Tunnels at High Altitude

In this paper, the numerical simulation software FDS is used to establish a full-size tunnel model to simulate a fire scene with a fire source power of 15 MW, and to study the influence of air curtains on the smoke propagation and temperature distribution of highway tunnel fires at different altitudes. It provides reference material for subsequent research on high-altitude tunnel construction, personnel escape and evacuation, smoke prevention and control, and tunnel structure design. This paper analyzes the distribution of smoke temperature, visibility, and CO concentration in various regions of tunnels at different altitudes when air curtains are applied, and explores the fire smoke spreading and temperature distribution law in tunnels at different altitudes under air curtain conditions. The results of the study showed that the smoke control effect of air curtains at different altitudes had a slight decrease with increasing altitude and was generally stable; The peak temperature that can be achieved by burning above a tunnel fire under an air curtain decreases with increasing altitude over the simulation time period; In the pre-combustion phase of a fire, the temperature at different altitudes at the same moment increases with decreasing pressure, the fire combustion of the middle and late law is the opposite; When the altitude is too high, there is a possibility of asphyxiation extinguishing the tunnel fire under the air curtain; before the fire source reaches the maximum combustion rate, in the range of 0 m-3600 m above sea level, the temperature and visibility of the evacuation area on the left side of the air curtain at the height of the human body are stabilized at below 66 degrees C and above 10 m respectively, which meets the requirements of personnel escape, and the temperature and visibility of the smoke control area increases with the increase of the altitude; the use of air curtains can have the ability of effective obstruction to diffusion and spreading of CO, and there is a slight decrease in the ability of the air curtains to obstruct the CO with the increase of the altitude.