Experimental and numerical simulation on smoke control effect and key parameters of Push-pull air curtain in tunnel fire

• Published in: Tunnelling and underground space technology 2022-03, Vol.121, p.104323, Article 104323
• Main Authors: Ji, Jingwei, Lu, Wen, Li, Fuqing, Cui, Xiaoting
• Format: Article
• Language: English
• Subjects: Air curtains; Air flow; Experiment; FDS; Fire protection; Mathematical models; Momentum; Push-Pull Air curtain; Smoke; Smoke control; Smoke detectors; Tunnel fire; Tunnels; Vertical air currents
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2021.104323

•The integrity of push–pull airflow influences the smoke control effect greatly.•When the momentum ratio R ≥ 6.5, the smoke control efficiency exceeds 90%.•Smoke accumulation is easy to occur within 5 m near the air curtain.•The escape door should be settled outside 10 m of the air curtain. A new type of push–pull air curtain was designed, and the smoke control effect was verified by carrying out a small-scale smoke control experiment in a model tunnel. The experimental results show that when the air volume of the system is the same, the smoke control effect of the push–pull air curtain is better than that of exhausting smoke from the side wall of the tunnel. The greater the velocity of the push air, the better the smoke control effect of the air curtain, and the effect of the jet velocity is greater than the cross-sectional area of the air curtain. FDS was used to numerically simulate the influence of factors such as air curtain spacing, air curtain width, push–pull airflow velocity in a tunnel of actual size on the effect of smoke control. The calculation results show that the smoke control ability of air curtain depends on the integrity of the air flow composed of incoming smoke and push–pull air flow. The smoke control efficiency E increases with the increase of momentum ratio R between push air flow of the curtain and incoming smoke flow. For the fire scene given in the paper, when the air curtain spacing is 80 m, the width of the push outlet and pull inlet are 0.6 m and 1.2 m, and the speed of push and pull air speed are 16 m/s and 23 m/s respectively; the momentum ratio R is greater than 6.5, and the smoke control efficiency E of the air curtain can exceed 90%.