室内火灾旋转火焰理论分析与实验研究

Theoretical analyses and experimental studies of whirling flames in enclosure fires

根据涡量传输和火灾动力学等理论,分析室内火灾旋转火焰的形成机理,导出室内火灾产生旋转火焰的控制因素表达式。旋转火焰的产生需要足够的密度梯度、压力梯度和斜压效应。利用小规模室内火灾实验,研究室内火灾旋转火焰的基本特征,比较旋转与非旋转火焰火灾的基本参数。与非旋转火焰的室内火灾比较,旋转火焰室内火灾热烟气层温度、升温速率、燃烧速率、地板所受辐射热通量等的均值与峰值均有显著提高,且峰值出现较早。结合理论分析与实验研究结果,得到了室内火灾发生旋转火焰的条件判据。

According to the theories of vorticity--transport and fire dynamics, the form mechanism of swirling flames in enclosure fires was analyzed, and the control factor expressions which swirling flames can be produced are deduced. The appearance of swirling flames needs enough density grads, pressure grads and barocline effect. The experiment of small--scale enclosure fires was used to study the characteristics of swirling flames in enclosure fires. The basic parameters of fire with and without swirling flames were compared. The average and peak value of smoke temperature, temperature increase rate, burning rate and the heat flux of radiation to floor in swirling flames are all bigger than that of non--swirling flames. Combining the results of theoretical analyses and experimental studies, the conditional criterion of swirling flames in enclosure fires is gained.