龙柏树冠火对相邻建筑的辐射特性研究

我国城市绿化覆盖率快速增长,带来了植被与建筑混合区域的火灾隐患。以常见城市绿化树种龙柏为研究对象,开展了单树树冠火对其相邻建筑的热辐射规律实验研究,测量了不同间距情况下建筑物一层和二层窗户位置的辐射热流密度,并在圆柱火焰模型的基础上,将圆柱火焰分为下层的稳定火焰区和上层的间歇火焰区,提出了分层圆柱火焰模型。结果表明,分层圆柱火焰模型可以准确描述树冠火辐射热流密度最大值随高度和距离的增加而递减的变化趋势。单一圆柱火焰模型理论的结果表明竖直方向上热流密度随高度变化不大,未能准确描述辐射热流密度竖向变化规律;分层圆柱火焰模型计算的辐射热流密度比单一圆柱火焰模型更符合实验结果,能更好地预测安全距离。

A study of radiation characteristics of cypress crown fire on adjacent structures

Rapid growth of urban green coverage rate in China may cause fire hazards in the mixing zone between vegetation and construction.In this work,cypress was used for the experimental study on the thermal radiation from a single tree crown fire to its adjacent structures.Radiant heat fluxes at the windows on the first and second floors were measured.On the basis of the cylindrical flame model,the layered cylindrical flame model,was established,in which the cylindrical flame is divided into the lower layer of persistent flame and the upper layer of intermittent flame.The results show that,layered cylindrical flame model can precisely describe the decrease tendency of the radiant heat flux maximums with increasing height and distance.The theoretical results of single cylindrical flame model show that the radiant heat flux changes little with height.It cannot describe the variation tendency of radiant heat flux maximums in vertical direction.As compared to the single cylindrical flame model,the radiant heat flux calculated by the layered cylindrical flame model has better agreement with the experimental results.The layered cylindrical flame model can be used to evaluate the safety separation distance for vegetation and construction interface fires.