基于P_n近似方法的消防水幕辐射传输模拟分析

Simulative analysis of radiative heat transfer in water curtains using P_n-approximation method

水幕系统对火焰辐射衰减问题包含了气体、水滴粒子、不完全燃烧产生的炭黑粒子等吸收、散射以及液滴蒸发吸热等过程。针对此问题,本文首先采用Mie散射理论与有效介质理论相结合,建立了水滴粒子以及炭黑掺杂混合液滴的吸收散射特性参数计算模型;在此基础上,考虑燃气辐射吸收作用,采用球谐函数法构造了多层半透明水幕介质的辐射传输计算模型。利用该模型分析了载液量、液滴粒径、水滴蒸发、粒子混合等因素对辐射衰减能力的影响。

The problem of thermal radiation shielding through water curtains is very complicated including absorption,scattering and evaporation absorbing heat processes of gases,water droplets and soot particles.In this paper,the Mie theory and effective medium theory are combined to build the model calculating absorption and scattering parameters of water droplet and mixed droplet containing soot particle,on this basis,taking into account the gases absorption effect the numerical model of radiative heat transfer in the multi-layer semitransparent water curtains are established using P_n-approximation method.By present model,the influence of droplet loading,droplet size,droplet evaporation and droplet mixing on the thermal shielding are systematically simulated and analyzed.