挑空空間自動撒水系統對火場煙層擾動之影響

The Interaction of Automatic Sprinkler and Smoke Layer Disturbance in High Ceiling Space

我國「各類場所消防安全設備設置標準」對於大規模挑空高達十公尺以上空間，滅火設備規定應設置放水型撒水設備，此類空間亦依規定須設置排煙設備。該標準對各項設備之設置有個別規定，然而研究文獻表示在挑空空間內撒水，會牽引氣流干擾煙層流動，因此煙霧會被牽引誘導而擴散而導致對人員避難安全問題。本研究建立實驗模型空間進行自動撒水對煙層擾動的物理實驗，建立一個放水型撒水的實驗系統，利用火盆產生熱煙測試撒水對煙流的影響，並採用美國NIST發展的FDS模擬軟體以3D電腦模型驗證。由實測結果發現，放水型撒水頭無論是安裝於天花板或側牆面，於啟動放水時，撒水之水滴流動會攪動煙層產生誘導氣流，造成煙層擴散沉降，電腦模擬結果與實測都得到相同之物理現象。電腦模擬發現較小之挑空空間，天花板型撒水頭因撒水的水滴流直接向下，會更迅速將煙氣向下方帶動，比側牆型撒水造成更嚴重的煙氣干擾。本研究再針對不同類型之挑空空間實例，建立電腦模型以FDS進行火災煙氣3D電腦模擬，針對自動撒水作動對煙層擾動模擬結果進行比對，並利用性能式安全設計方法之結果比較分析，找出減緩干擾煙層的重要因子，提出提升性能式火災安全設計的改善建議。

 

The fire safety regulations of Taiwan require 10 m above high ceiling space to install discharge type sprinklers. Smoke exhaust is also required for high ceiling space. It has been known that the interaction of smoke flow and sprinkler droplets may cause smoke layer be inducedand draged down.A discharge sprinkler experiment was setup to test the phenomena of smoke and sprinkler droplets interaction. The test results show that either the sprinkler is of ceiling or wall types, the sprinkler action would induce the downward flow of smoke and may affect the safe egress from fire. The physical phenomena in the experimental results agree with FDS simulation results. The computer simulation results show that smaller high ceiling spaces would have greater interaction of smoke and sprinkler action. The computer simulation also shows that for smaller high ceiling spaces, ceiling type sprinklers action would cause faster downward induced smoke flow. More case of computer model was built to simulate the 3D computer simulation of fire smoke with FDS. The simulation results of the smoke disturbance were compared for the automatic sprinkling operation, and the results of the performance-based safety design method were compared and analyzed. To identify important factors that mitigate the smoke layers, and propose improvements to improve performance-based fire safety design.