重点排烟作用下地下通道顶棚烟气温度分布研究

Effects of Central Smoke Extraction on Temperature Distribution Characteristics Under Ceiling in the Underground Passage Fires

本文通过改变重点排烟量及火源功率,研究了在不同重点排烟方式下,顶部重点排烟量对地下通道顶棚烟气温度分布的影响。研究发现:在无重点排烟条件下,由于热烟气的卷吸,以及与顶棚之间的传热影响,通道内的顶棚纵向烟气温升在不同火源功率下均随距离的增加而不断衰减。不同顶部重点排烟方式及火源功率下的顶棚烟气温度衰减趋势相同,且重点排烟量越大,顶棚纵向温度越低。本文引入了重点排烟量影响因子β,该影响因子随着重点排烟量的增加呈现指数增加。建立了顶部不同重点排烟模式下地下通道顶棚烟气温度分布模型,模型预测值与实验测量值吻合较好。

The smoke temperature profile under the ceiling in the underground passage fires with ceiling central smoke extraction modes （by changing HRR and exhaust rate） was studied by reduced model scale experiments. The results show that, without ceiling central smoke extraction, the ceiling smoke temperature rise decay along longitudinal direction of the underground passage due to the coupling effect of air entrainment and heat transfer between the hot smoke and ceiling. The decay trend of smoke temperature under different central smoke extraction modes and HRR are same. And the smoke temperature beneath ceiling decreases with the increasing of exhaust rate. The impact factor of exhaust rate was proposed to describe the effect of ceiling central smoke extraction. The impact factor exponential increases with the central exhaust rate. A new model is proposed to describe the temperature distribution characteristics in underground passage fires under different central smoke extraction modes. And the model prediction results are in good agreement with the experimental data.