Experimental Study on the Isolation Effect of Air Curtain System in Bifurcation Tunnel Fire

The complexity of urban tunnel structure increases the risk of tunnel fire, and the air curtain system plays an important role in controlling the spread of fire smoke and ensuring the safety of personnel. Based on theoretical analysis and tunnel model experiments, the isolation effect of different air curtain jet conditions on high-temperature fire smoke in bifurcated tunnel was studied. The results show that the air curtain system can effectively isolate the high-temperature smoke. For different firepower, compared to angle and thickness, wind speed has the best control effect on high-temperature smoke. The control effect of air curtain thickness takes second place. The effect of angle change is the least obvious. Meanwhile, based on the analysis of experimental results, it was found that when the air curtain parameters are selected as wind speed of 2.5 m/s, angle of 15°, and thickness of 0.16 m, the air curtain system has better smoke prevention efficiency. Finally, dimensionless analysis yielded a power law equation relating upstream temperature rise, firepower, and wind speed. This supports theoretically analyzing the air curtain's smoke prevention effect.