空气幕-顶部排烟系统控烟排烟有效性的研究

在火源两侧设置两道空气幕能有效阻隔火灾蔓延和烟气扩散。为了探明低射流风速下空气幕在点式集中排烟隧道内对火灾特征参数的影响,通过FDS研究了不同排烟量、射流速度和射流角度下隧道内烟气蔓延、温度分布和排烟效率的变化。结果表明:当HRR为30 MW时,射流速度至少应不小于2.5 m/s才能保证空气幕的隔烟作用;当射流速度在2.5 m/s以下时,射流角度越大空气幕的隔烟效果越差,这明显不同于射流速度较大的情形;空气幕能很容易地将空气幕外的温度控制在40 ℃以下,射流角度对逃生区域的温度分布影响不大,主要影响火羽流的分布;相同射流角度下排烟量越大排烟效率先升高后减小,而相同排烟量下随着射流角度的增大排烟效率逐渐减小;对于30 MW的火灾规模,推荐的控烟方案为:射流速度为2.5 m/s,排烟量为120 m³/s。

Study on the Effectiveness of Smoke Control of Air Curtain-top Exhaust System

Two air curtains on both sides of the fire source can effectively block the spread of fire and smoke. In order to find out the influence of air curtain on the fire characteristic parameters in a point type centralized smoke exhaust tunnel under low jet velocity of air curtain, the smoke spread, temperature distribution and smoke exhaust efficiency at exhaust vent in the tunnel under different smoke exhaust volumes, jet velocities and jet angles were studied by FDS. The results show that when the HRR is 30 MW, the jet velocity should be no less than 2.5 m/s to ensure the smoke control effect of air curtain; when the jet velocity is below 2.5 m/s, the larger the jet angle is, the worse the smoke control effect of the air curtain is, which is obviously different from the case of larger jet velocity; the air curtain can easily control the temperature outside the air curtain below 40 ℃, and the jet angle has little effect on the temperature distribution of the escape area, mainly on the distribution of the fire plume; with the increase of the exhaust volume, the exhaust efficiency first increases and then decreases; for a 30 MW fire scale, the recommended smoke control scheme is: jet velocity of 2.5 m/s and smoke exhaust volume of 120 m³/s.