以FDS模擬分析可燃天花板及火源位置對居室延燒之影響

Abstract

本研究是使用FDS模擬一簡單居室之火災行為(包含火場之溫度、能見度、一氧化碳、氣體流動速度及煙粒子軌跡)，居室內包含三張沙發、木桌及電視機等擺設物，其材質分別為PU發泡棉、白杉(White Pine)及PVC材質。在居室內設定一火源作為引燃條件，火源以極快速(Ultra-fast)成長曲線從開始引燃到達最大熱釋放率1,000 kW。藉由模擬火源從引燃成長，歷經閃燃後變成全盛期火焰的整個火災歷程，探討天花板、壁面裝修材料及傢俱的材質、通風口關閉時間及引燃火源位置對火災成長的影響。並觀察各情境的造成遠處物熱輻射延燒的影響與差異。 經模擬結果顯示，可以觀察到整個火災歷程，以情境一-1為例，閃燃時間發生為175秒，火災全盛期為175~1100秒；衰減期為1100~1800秒。而將此情境與實驗比較，實驗大約2分半(150秒)達到閃燃，而模擬達到閃燃約為175秒，模擬可以更精確預測閃燃時間。火源位置於牆角與天花板加裝壁裝材料，閃燃時間都會提前發生。 三種不同壁裝材質以居室內以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。

This thesis applies FDS (Fire Dynamic Simulator) numerically study the fire development process in a fire compartment, where contains three sofas, wooden tables and TV sets. The corresponding materials are PU foam, white pine and PVC, respectively. A fire source is set as the ignition source, whose maximum is 1,000kW reached by an ultra-fast growth rate. The parameters include the material properties of the ceiling, wall decoration and furniture, the location of ignition source, and the ventilation opening time. It also intends to observe the effect of fire radiation on the ignition of other combustible objects far away from the ignition source. The simulation results are able to illustrate the complete fire development in a quantity way. Taking case1-1 as an example, the flashover time occurs at 175-seconds, the fully developed period is 175 ~ 1100 seconds, and the decay period is ranged from 1100- to 1200-second. In the similar experiment carried out by NIST, it takes about 150 seconds to reach flashover that agrees well with present simulation. Fire source in the corner and ceiling with combustible decoration materials make the flashover to happen earilier. Three different wall decoration materials (PU Foam, PVC and White pine) are used to investigate the corresponding flame spread behaviors in a fire compartment. PU Foam is found to the fastest fire spread, leading to a worst fire hazard. This behavior completely agree with the fire test observation carried out by ABRI.