以 FDS 模擬分析火災延燒

Abstract

本研究主要是探討使用FDS建立火災之延燒模擬。根據相關文獻的參考資料，假設一簡單居室之發生火災，居室內有椅子、木桌及電視機擺設物，擺設傢俱各以三種主要材質做成，分別為PU發泡棉、白杉(White pine)及PVC材質，同時採用四種不同裝潢材料分別為北美黃杉 (Douglas fir)、PU發泡棉、PVC材質及白杉 (White pine)研究，以不同情境探討不同裝潢材料對居室延燒之影響。居室內給定一火源條件下，以普通(Medium)之成長曲線到達最大熱釋放率1MW，探討相同火源燃燒面積因不同裝潢材料造成延燒遠處物延燒的影響與差異。 本研究以四個情境探討延燒模擬，木材之情境幾乎都在模擬約300秒時發生閃燃，而聚合物則約在400秒秒時發生閃燃其中四種使用的裝潢材料以PU發泡棉最容易被引燃且蔓延，模擬結束時房間內的傢俱幾乎燃燒殆盡，而木頭材質、PVC材質較慢被引燃。居室內以PU發泡棉製成的沙發燃燒最為劇烈，此與建研所建築空間火災特性之分析與印證-住宅單元之實尺寸火災特性分析-沙發椅燃燒試驗分析，提出防止火焰進入沙發內部為避免火勢迅速增大之重要因素，有相同趨勢。

In the past, many researchers and performance-based designs used FDS (Fire Dynamics Simulator) to simulate and investigate the smoke movement in the large scale or complex architecture/constructions. In such case, the designed fire is the only source of heat release rate. However, in many fire incidents, the heat release rate usually is greatly enhanced by fire spread over the combustible materials, especially the wall decoration. When a fire occurs incidentally in a compartment, it can grow by means of the heat transfer (conduction, convection and radiation) to pyrolyze the other surrounding combustibles to generate more fuel vapors to feedback into the fire to let it become stronger and capable of further wider spreading. The cycle repeats continuously. Even if the air in the compartment is depleted or lowered to a certain limit, the resultant high temperature still keeps on the pyrolysis action. Once an opening happens to let air flow into the space, it leads to flashover. During the process, wall decoration plays the major role for fire spreading in addition to the furniture and electrical appliances in the space. If the corresponding material is flammable and combustible, then it can contribute to severe fire spread, especially the vertical wall surfaces. The parametric study is given by using 4 different wall decoration materials (PU Foam, White pine, PVC and Douglas fir) to investigate the corresponding flame spreads in a fire compartment. PU Foam is found easy to be ignited and the spreading fire behavior is the worst one. Inside the room, PU Foam walls are almost burnout at the end of simulation and it causes severe damage. In the meantime, sofas made by PU foam are ignited easily and burned fiercely as well.