穿透风对外部燃烧火焰影响的数值模拟

为研究室内火灾的外部燃烧现象,该文应用FDS(fire dynamic simulator)程序,采用大涡模拟(LES)湍流模型,对穿透风对外部燃烧火焰的影响进行了数值模拟研究。计算结果解释了Law的经验公式与Klopovic的实验观测之间的矛盾,并且给出Law经验公式的适用范围。计算结果显示,存在两个穿透风的临界速度当穿透风风速大于第一临界速度时,Law的关于外部燃烧火焰高度的公式定性正确;当穿透风风速大于第二临界速度时,Law的关于外部燃烧火焰长度的公式定性正确;数值计算得到的火焰宽度随风速的变化趋势与Law经验公式的预测结果相反,但与Klopovic的实验观测一致。

Numerical simulations of the effect of the through draft on external flames in compartment fires

The effect of the through draft on an external flame was investigated using the fire dynamics simulator (FDS) code with the large eddy simulation (LES) approach. The numerical results illustrate the reasons for the discrepancies between Klopovic's experimental results and Law's formula and give the limits of application of Law's empirical formula. Through drafts were found to have two critical velocities. When the through draft velocityis larger than the first critical velocity, Law's correlation for the height of the venting flame is qualitatively accurate. When the through draft velocity is larger than the second critical velocity, Law's correlation for the horizontal length of the venting flame is also qualitatively accurate. However, the variations of the venting flame width are contrary to Law's correlation, but agree with Klopovic's experiments.