室外风对高层建筑着火楼层机械排烟效果的影响

INFLUENCES OF OUTDOOR WIND ON EFFECT OF MECHANICAL SMOKE EXHUAST OF FIRE FLOORS IN HIGH-RISE BUILDINGS

以南京市某15层长廊型高层建筑办公楼为研究对象,采用FDS(fire dynamic simulation)对室外风影响下的着火层长廊内不同防排烟模式以及不同高度着火楼层的火灾烟气运动情况进行分析。当室外风风速为0 m/s时,长廊内ρ(CO_2)为6 160 mg/m^3,自然排烟可以满足人员逃生的需求;当室外风风速为2.4 m/s时,长廊内ρ(CO_2)为10 084 mg/m^3,仅通过自然排烟不能满足人员逃生需求,需加设机械排烟降低长廊内CO_2浓度。由于室外风随着高度呈指数型增加,不同高度相同物理模型的着火楼层在相同的排烟模式下,长廊内CO_2浓度随着着火楼层高度的增大而增加,且着火楼层为12层及12层以上时,传统的机械排烟模式不能满足长廊内人员的逃生需求。而应根据长廊内CO_2的浓度相应地增加机械排烟量。

Abstract:In this paper,taking a 15^th floor corridor type high-rise office building in Nanjing as the research object,FDS (Fire Dynamic Simulation)is used to analyze different smoke control modes in fire floor corridor and fire smoke movement in different fire floors under the influence of wind outdoor.When the speed of outdoor wind is 0m/s,the CO2concentration in the corridor is 6160mg/m^3,so that people can escape with natural smoke exhaust.When the speed of outdoor wind is 2.4m/s,the CO2concentration in the corridor is 10084mg/m^3,which cannot meet the needs of people to escape with natural smoke exhaust.Thus additional mechanical smoke exhaust is necessary to reduce the CO2concentration in the corridor. Because the speed of outdoor wind increases in exponential type with height,the CO2concentration in the corridor increases with the height of fire floor under the same smoke exhaust mode for the same physical model with different heights.What is more,the amount of mechanical smoke exhaust should be increased according to the concentration of CO2in the corridor when the fire floor is 12or above,because the traditional mechanical smoke exhaust mode can't enable the people in the corridor to escape.