大型综合购物广场中庭火灾烟气的数值模拟

中庭火灾的烟气流动与控制数值模拟是性能化消防设计的关键。借助Fluent软件,以广州某广场中庭为实例,考虑火源位置和补风口位置两因素,设计了不同的中庭类建筑火灾场景,并建立了数值模型。结果表明:当补风口稍高于火源时,不仅对火源的影响较小,还有利于烟气的排出;烟气中的CO向远距离处迁移时浓度变化较小;发生火灾时,中庭底部烟气的毒性危害高于烟气的高温危害。

Numerical simulation of the smoke movement in fires on large shopping plaza atrium buildings

The article is devoted to a numerical simulation for the smoke movement and control in atrium fires,which should be taken as a key to the performance-based fire safety plot.In the article,we have adopted a software named Fluent in illustrating all the different fire scenarios likely-to-be predicted in atrium buildings of a shopping plaza by taking some one in Guangzhou for setting up a numerical model while considering the position of combustion source and the air tuyere.At the same time,we have introduced the field model and the radiation exchange model for the smoke flow and turbulence in the building under strong buoyancy uprising.The reason why we have chosen a partially premixed combustion model is that the fire burning process here belongs neither to the diffusion combustion nor to the well-mixed premixed combustion,rather a violent burning that may lead to a more complicated combustion process.The results from our simulation show that the location of the fire source may not have much impact on the declining speed of the smoke layer but the rising speed of the smoke temperature,for the higher location of the air tuyere is likely to restrict the sufficient burning of the combustibles and make it easier for outside air supplement,which can not only be useful for controlling the fire source,but also beneficial for the smoke discharge.Therefore,such factors are favorable for lowering the temperature in the building.What is more,the smoke is less toxically harmful when the fire spreads to the center of atrium as compared to the situation when the combustion starts from the corner.On the other hand,if the fire breaks out in the corners of atrium,it has to take longer minutes to reach the other parts of the building for the long distance between the fire and tuyeres may help to impede the smoke discharge.On the other hand,while the fire is going on,since the CO concentrations change little when the smoke moves further,the smoke temperature rising may be relatively slow at the bottom of atrium whereas the CO concentrations grow relatively fast,which turns to result in higher damages in toxicity than in high temperature.This study has thus brought about a useful reference to the engineering design in the atrium smoke control system and safety evacuation research.