水喷淋与机械排烟作用下小室火灾特性的实验研究

Experimental Studies on Cabin Fire under Sprinkler and Mechanical Smoke Exhaust

采用全尺寸实验对水喷淋和机械排烟作用下的小室火灾特性展开了研究,揭示了小室内烟气温度、CO浓度的变化规律。结果表明,对于一定规模的火灾,存在水喷淋压力和风机风量的临界组合,来对水喷淋和机械排烟共同作用时的控火和灭火两种效果进行转换。水喷淋的作用可以有效降低小室内烟气温度,抑制轰燃发生,但是也会产生大量的烟水混合气。灭火时,小室内的烟气温度是持续下降;而控火时,小室内的烟气温度会平稳一段时间,再慢慢下降。CO浓度在水喷淋作用后会急剧增加,控火时存在两个峰值,灭火时只有一个峰值。水喷淋的压力是其中关键的参数,而风机风量只是一个次要的参数,两种系统的作用效果相反。控火时,CO生成量随着水喷淋压力的增加而增加,随着风机风量的增加而降低。这些都为大空间内小室水喷淋系统和机械排烟系统的设计提供了基础的实验依据。

Full-scale burning tests were carried out to study cabin fire under sprinkler and mechanical smoke exhaust. Smoke temperature and CO concentration in cabin were obtained. Results showed, some critical combinations of the pressure and fan extraction rate were found on controlling or extinguishing the fire. Smoke temperature in cabin could be reduced in effect under sprinkler to suppress flashover, but much smoke mixed with vapor was produced. Smoke temperature in cabin descended continuously under extinguishing fire, but remained stable during a period of time, then descended slowly under controlling fire. After sprinkler was operated, CO concentration increased sharply. There were two peaks under controlling fire, but one peak under extinguishing fire. The pressure of sprinkler was the key factor, and the fan extraction rate was the secondary factor. The effects of these two systems were contrary. CO production rate increased with increasing sprinkler pressure, and decreased with increasing extraction rate of the fan under controlling fire. All these offered the basic experiment data for the design of cabin＇s sprinkler system and mechanical smoke exhaust system in large space building.