地下高大空间火灾烟气自由填充试验研究

Experimental analysis of the natural smoke filling in large underground space

利用费诺德(Froude number)相似模型理论,建立1∶12的某地下高大空间(高大空间为高度大于10 m,体积大于10 000 m^3)比例模型,研究了地下高大空间火灾烟气自由填充过程及温度变化特性。1∶12模型试验结果和火灾动力学模拟(fire dynamics simulator,FDS)模拟值与McCaffrey预测值吻合度较高。1∶12火灾模型试验能较好的预测地下大空间烟气流动特点,且是验证数值结果正确性的重要手段。试验表明:高大空间"蓄烟效应"显著,火灾发生时高大空间竖向温度呈线性分布,且温升较小,温度不是影响人员逃生和排烟效果的主要因素;火源位置分别处于模型端部的烟气层下降速度慢于中心位置。该研究为制订火灾排烟和疏散方案及高大空间防排烟规范提供了初步理论依据和第一手的试验资料。

A 1/12 scale model of a large underground space is set up according to the Froude modeling theory to investigate the characteristics of natural smoke filling in the space, the temperature field and strength distribution. Results show that the experimental, FDS simulated values are in good agreements with each other. The experiments can well predict the smoke movement in large underground space, and it is feasible to verify the validity of simulated results using proportional scaling model. Because of the huge space, the "smoke storage phenomena" is very significant. The vertical temperature presents a linear distribution under fire, which suggests that smoke temperature is not the major factor influencing evacuation and mechanical smoke extraction design. The smoke descends more slowly at the headwall than that in the center. The investigation can provide theoretical basis and experimental data for further study on mechanical smoke extraction of underground space, and also itbenefits towork out the smoke control standard of huge space.