Simulation of fire in subsurface space

本年度进行的实验结果如下：PMMA棒在管道中的燃烧特性。PMMA棒在管道中燃烧，作为电缆火灾的替代品。为模拟地下空间电缆火灾，对PMMA棒的燃烧特性、火焰蔓延速度和燃烧烟气进行了测量。结果表明：1)无气流条件下无法维持直径为10mm的燃烧；2)风速大于0.5 m/s时燃烧变得强烈；3)在靠近风道顶部的位置支撑杆时火焰的蔓延速度加快，但在其他条件下速度没有明显增加。基于激光光片的巷道流动可视化研究建立了新型拱支撑巷道模型，并对巷道内流动进行了测量。在支架附近存在大量涡流，但有支架和无支架模型巷道内主流无本质差异。另外，还对迎头附近有障碍物的模型进行了测量。开发模拟地下空间火灾的计算机程序，除了程序本身的开发外，还发现了几个重要的条件，即计算边界与通风管道之间的距离要大，网格的尺寸要小，否则不能保证计算的准确性。

The results of experiments executed in this year are as follows.1. Characteristics of combustion of a PMMA rod in a duct.Rods of PMMA were burned in a duct as a substitute for a cable fire. The burning characteristics, the spreading speed of the flame and the fume of the combustion, of the PMMA rods were measured for the simulation of a cable fire in subsurface space. Then, 1) a combustion of 10 mm diameter rod could not be maintained under the condition of no airflow, 2) the combustion became intense when the air speed was more than 0.5 m/s, 3) the spreading speed of the flame became faster when the rod was supported near the roof of the duct although there were no apparent increase of the speed in another condition.2. Visualization of flow using laser light sheetA new roadway model with arch supports was made and the flow inside was measured. There were a lots of eddy near the supports, however, there was no essential difference in the main flow in the roadway between the models with and without supports. A model with some obstruct near the heading face was also measured.3. Development of a computer program to simulate a fire in subsurface spaceThere found several important conditions in addition to the development of the program itself, that is, the distance between boundary of the calculation and the ventilation duct should be large and the size of grid should be small or the accuracy can not be assured.