基于炭化痕迹的火灾数值重构及应用

利用试验方法建立了炭化痕迹的数学模型,与火灾流体动力学软件FDS相耦合,实现对炭化痕迹的再现,同时,进行了较为接近真实火灾的火灾场景试验,并用新编译的FDS软件对试验进行重构。结果表明:火势发展变化趋势基本一致;起火后,火场热释放速率迅速上升,100 s左右达到约2750 kW,随后开始下降,直至434 s降到700kW左右,与火势进程基本吻合;试验得到的密度板炭化痕迹未被烧损的区域(横向30.2~86.8 cm、纵向0~18.6 cm)略小于重构得到的密度板炭化痕迹未被烧损的区域(横向33.4~91.6 cm、纵向0~18.9cm),但分布规律基本一致,验证了新编译的FDS软件的有效性。将该软件应用于消防工作,不仅可以作为一种定量方法来描述炭化痕迹的形成过程,还可以通过火场中的炭化痕迹来反推起火点位置,辅助火灾调查工作。

Reconstruction of the fire numerical simulation and its application in carbonization trace

The purpose of this article is to verify the assumption of the mathematic model of the carbonized trace FDS program and reestablish the fire scene historical process in addition to the carbonized trace of the density board.It is just for the said purpose that we have done the following simulated experiments.First of all,we have established a mathematical model of carbonization in hoping to realize the carbonization trace by associating it with the CFD software FDS.And,then,the fire scenario has been imitated as much close to the real fire scenario,with the fire growing process recorded by a video camera and the carbonized traces of density board recorded with a digital camera.And,last of all,efforts have been made to reconstruct the fire scene experiment through a newly compiled FDS program,in which the growing process of the fire,the heat release rate and the carbonization traces of density board are to be perfectly worked out.And,then,comparing the results of the experiment and the reconstruction,may let us clarify that the growing process of the fire obtained from fire scene experiment tends to be consistent with the reconstruction calculation in the following manner:at the stage of ignition,the heat tends to release at a fast increasing rate;and,afterwards,when the fire reaches about 2 750 kW in about 100 s,it would begin to decline to as much as about 700 kW until 434 s.It is also possible for us to find the effect of the carbonization trace on the unburned area of the density board from the fire scene experiment,say,whose lateral distance is 30.2-86.8 cm and whose vertical distance is about 0-18.6 cm,a bit smaller than that gained from the reconstruction calculation.Moreover,we can also find the fire trace in the lateral(33.4-91.6 cm) and longitudinal (0-18.9 cm) direction,though they may both share the same distributive share,for the result that can be verified by the newly compiled software.Thus,the modified software has not only been proved to be valuable as a quantitative calculating means to describe the carbonization resulting procedure,but also effective to determine the fire point position through the carbonization trace,which turns to be highly beneficial for the fire history-tracing investigation.