Numerical Simulation Study on Smoke Control in Urban Bifurcated Tunnel Under the Effect of Air Curtain

Abstract

With the increasing congestion of urban ground traffic flow, underground traffic has become a main choice to ease this situation. Due to the complexity of inner structure in bifurcated tunnel, the fire scenario and smoke movement of urban bifurcated tunnel differs from that of common tunnel. Based on FDS, this paper builds a numerical model to study the correlation between the smoke control effect of the air curtain and the other terms which include fire source position, fire heat release rate, air curtain flow rate and air curtain angle in the urban bifurcated tunnels. The results shows that when the fire heat release rate is 20MW and the air curtain flow rate is 10m/s, or the fire heat release rate is 10MW or 5MW and the air curtain flow rate is 8m/s, smoke can be effectively controlled. And, the smoke control effect of the air curtain is closely related to the position of fire source, the fire source position at 20m has the best smoke control effect, followed by -20m, and the worst at 0m. Besides that, the faster the flow rate of air curtain is, the better the smoke control effect is. In addition, when the fire source is located at 20m and the air curtain flow rate is 10m/s or the fire source is at 0m or -20m and the air curtain flow rate is 12m/s, it can effectively control smoke. Moreover, when the angle of air curtain is -15°, the smoke control effect is the best.