单室火灾烟气运动的双层区域模拟

室内火灾双层区域模拟中需考虑到压力的变化,利用热力学第一定律推导了室内气体参数随时间变化的常微分控制方程组.该方程组刚性,可采用吉尔算法求解.在选用Heskestad羽流公式的基础上,计算了某单室火灾在房间平面面积与机械排烟量分别为49m2,0.3m3/s;49m2,0.4m3/s;100m2,0.3m3/s;100m2,0.4m3/s四种工况下室内与室外压差、烟层高度、上层烟气温度、下层空气温度随时间的变化规律.结果显示:室外压差随时间变化迅速;Heskestad与Mcaffrey羽流模型在算例中具有较好相似性;烟层的下降与上层烟气温度的升高较多地受到房间平面面积的影响,而受顶部排烟量的影响较少.

Two-layer zonal modeling of smoke movement in single fire room

In indoor fire's two-layer zonal modeling,the variation of indoor pressure should be considered.The first law of thermodynamics is utilized to derive a set of ordinary differential controlling equations in which indoor gas parameters changes with time.These equations are stiff,but a Gear algorithm can be adapted to it.Based on the selected Heskestad plume model,the time-dependent variation regularity of pressure differences between indoor and outdoor,smoke heights,upper layer smoke temperatures,and lower layer air temperatures have been calculated for a single fire room with floor areas and mechanical exhaust smoke rates of 49m2,0.3m3/s;49m2,0.4m3/s;100m2,0.3m3/s;100m2,0.4m3/s respectively.Results show that pressure difference changes with time quickly;Heskestad and Mcaffrey plume models have a better similarity;Decreasing of smoke height and increasing of upper layer smoke temperatures are influenced more by floor areas than by top exhaust smoke rates.