Experimental study on fire temperature distribution based on air curtain separation effect in a reduced-scale bifurcation tunnel

Abstract

Previous studies have mainly focused on the traditional smoke prevention and exhaustion system in the simple structure of the tunnel. For bifurcation tunnel with air curtain, the temperature characteristic and the ability of air curtain to attenuate heat radiation and block the spread of smoke are still unclear. In this paper, a series of experiments were carried out in a 1:10 scale bifurcation tunnel to study the separation effects of air curtain by changing the wind speed, angle, and thickness. Results show that air curtain has a significantly blocked effect from main tunnel to the branch. Compared with the angle and thickness of air curtain, the cooling effect of wind speed is more stable. The temperature on the central axis of the main tunnel ceiling reduces with the increase of the wind speed. Plus, the laws of positive and negative angles acting on the tunnel are not consistent. When angle of air curtain acts, the temperature change on the left side is different from the right in the main tunnel. Besides that, the temperature reduces firstly and then rises with the thickness broadening. Then combined the temperature attenuation data along the main tunnel, a dimensionless temperature attenuation model was established, and a unified model under various heat release rates is obtained.