基于FDS模拟的外界风对瘦高型中庭建筑机械排烟的影响研究

Research on the Influence of External Wind on Mechanical Smoke Exhaust in Tall and Thin Atrium Buildings Based on FDS Simulation

机械排烟是控制瘦高型中庭建筑中庭火灾烟气的主要方法,利用FDS模拟方法,对影响中庭机械排烟的因素进行分析,研究结果表明:机械排烟时,外界风使新鲜空气从补风口进入,外界风速越大,补入空气产生的惯性力越大,使中庭内的换气速率增大,可以及时的把烟气排到室外.机械排烟速度的大小直接影响排烟效果,机械排烟速度过小时,受外界风的影响,不仅不利于排烟,而且还会使整个中庭充满烟气;机械排烟速度合适时,外界风加速了中庭内部的烟气置换,对烟气起到良好的稀释作用,并且增大了能见度.机械排烟速度大时,从250 s开始时,中庭顶部的温度稳定在30℃左右,中庭内的最高温度不超过100℃;机械排烟速度小时,从400 s开始时,中庭顶部的温度稳定在50℃左右,中庭内的最高温度达到240℃;机械排烟速度小时,中庭内的温度整体上都高于机械排烟速度大时中庭内的温度.

Mechanical smoke exhaust is the main method for controlling smoke in atrium fires of tall and thin atrium buildings.Using FDS simulation method,the factors affecting mechanical smoke exhaust in atrium are analyzed.The research results show that during mechanical smoke exhaust,external wind causes fresh air to enter from the air inlet.The higher the external wind speed,the greater the inertial force generated by the air inlet,which increases the ventilation rate inside the atrium and can timely exhaust smoke to the outside.The speed of mechanical smoke exhaust directly affects the smoke exhaust effect.If the speed of mechanical smoke exhaust is too small,it is affected by external wind,which not only hinders smoke exhaust,but also fills the entire atrium with smoke.When the mechanical smoke exhaust speed is appropriate,the external wind accelerates the displacement of smoke inside the atrium,which has a good dilution effect on the smoke and increases visibility.When the mechanical smoke exhaust speed is high,starting from 250 s,the temperature at the top of the atrium stabilizes at around 30℃,and the highest temperature inside the atrium does not exceed100℃.When the mechanical smoke exhaust speed is low,starting from 400 s,the temperature at the top of the atrium stabilizes at around 50℃,and the highest temperature inside the atrium reaches 240℃.When the mechanical smoke exhaust speed is low,the overall temperature in the atrium is higher than that of the atrium when the mechanical smoke exhaust speed is high.