细水雾对不同开口受限空间火灾的抑制作用

摘要

A 3.6 m long,1.5 m wide and 0.6 m high water mist fire suppression test model was set up with the spray nozzle 1 100 mm away from the main fuel.In the center of the experimental model,500 mm diameter alcohol pool is set as the fire source.Under natural ventilation conditions,water mist was started after ignition 8 minutes.By changing location and quantity of the vent openings and water mist spray pressures,water mist fire suppression mechanisms and effectiveness were analyzed.The experimental results show that,for in confined spaces with double openings,water mist with 6 MPa and below the pressure can effectively inhibit the flashover,but cannot achieve 175 kW ethanol pool fire.When the spray pressure was increased to 7 MPa,8.37 L/min water mist can effectively suppress the 175 kW fire with 54 s,which is about 1 minute earlier than the fire suppression time in the same confined test model with one single opening.The key mechanisms of water mist fire suppression in confined spaces with double openings are the water mist's cooling effect to the flame and the upper hot smoke layer.For the confined spaces with one single openings,the key mechanisms are the attenuation to the radiant heat flux and the cooling effect to fuel surfaces.%目的 研究单、双开口受限空间自然通风条件下,细水雾抑制酒精池火的机理和有效性.方法 在3.6m×1.5 m×0.6m的实验模型中部设置直径500 mm酒精作为火源,距离火源中心1 100 mm的位置布置高压细水雾喷头.在自然通风工况下,点火8 min后启动细水雾,改变开口的位置、数量及细水雾施加压力,对比分析不同开口条件下细水雾灭火的机理和有效性.结果 对于双开口受限空间175 kW酒精池火,6 MPa及以下的细水雾可以有效抑制轰燃,但不能实现灭火;7 MPa、8.37 L/min细水雾可在54 s内有效灭火,比单开口受限空间灭火时间缩短了56 s.结论 细水雾熄灭双开口受限空间酒精火的主导机理是对火焰和热烟气层的冷却作用,细水雾熄灭单开口受限空间火灾的主导机理是对地面接受到的热辐射的冷却作用.