室内火灾烟气运动及机械排烟的大涡模拟

采用机械排烟是控制建筑火灾烟气扩散与蔓延的一种有效手段。利用大涡模拟方法,对建筑物室内火灾烟气运动及机械排烟进行了数值模拟。在室内后侧墙处有机械排烟口的条件下,模拟得到的烟气瞬时温度随时间的变化与实验相符合,计算出的烟气层高度也与实验相符合。通过数值模拟对室内机械排烟口的位置进行了优化选取,表明机械排烟口的不同位置对室内烟气运动有较大的影响。当火源位于房间地面中心时,在顶棚中心或左端中心实施机械排烟比在后侧墙处实施机械排烟可取得较好的排烟效果。这说明将排烟口布置在沿烟气运动趋势较强的路径且远离进风口处,可有效地控制室内烟气层的高度。

Large eddy simulation of fire smoke flow and mechanical smoke exhaust in a room

Mechanical smoke exhaust is an effective way to control smoke flow and diffusion in building fires.Large eddy simulation was utilized herein to investigate the fire smoke flow and mechanical smoke exhaust in a building room.Under the condition that the mechanical smoke exhaust exit located at the rear wall,the predicted instantaneous variations of the smoke temperature with time agree with the measurements.The calculated height of the smoke layer also agrees with the measured test data.The location of the mechanical exhaust exit was optimized through the numerical simulations.It is found that the smoke flow in the room is evidently affected by different locations of the mechanical exhaust exit.When the fire source is placed at the center of the floor,the smoke extraction can be better achieved if the mechanical exhaust exit is located at the center of the ceiling or at the left-end center of the ceiling than at the rear wall.The results indicate that the mechanical exhaust exit should be arranged on the pathway with relatively strong tendency of smoke flow and far away from the air intake to effectively control the height of the smoke layer.