本文選題：火災調(diào)查　切入點：煙熏痕跡　出處：《天津商業(yè)大學》2013年碩士論文

【摘要】：壁面煙熏痕跡是火災調(diào)查工作中的重要研究內(nèi)容，在某些火災現(xiàn)場，由于地面痕跡和燃燒剩余產(chǎn)物在撲救的過程中被破壞，壁面煙熏痕跡的研究價值就變得尤為重要。火災壁面煙熏痕跡形成的主要原因是火災煙氣中的游離碳等物質(zhì)被吸附到壁面表面或縫隙中。所以，要研究壁面煙熏痕跡的形成規(guī)律，首先要研究火災煙氣的運動。影響火災煙氣運動的因素有很多，本文主要探究火場通風對火災煙熏痕跡形成規(guī)律的影響，通過理論模型分析、實體模型實驗和數(shù)值模擬來研究探討相關規(guī)律。 本文在分析前人研究成果的基礎上，，首先利用點源模型理論，通過使用拋物線來表征壁面V型煙熏痕的跡輪廓曲線，確定了無風條件下火源煙氣羽流與壁面位置關系對V型煙熏痕跡的影響，并依據(jù)實驗測量結(jié)果擬合出了煙羽流的錐體母線。在此基礎之上，在模型房間內(nèi)設置了三種不同布局的火源，通過實驗研究自然排煙和機械排煙條件下，室內(nèi)火災壁面煙熏痕跡的變化規(guī)律。 室內(nèi)火源布局為中心火時，自然排煙條件下壁面痕跡的最薄處應處于火源的正上方。通風使得壁面頂部煙熏痕跡的厚度降低，火源燃燒時間縮短，并導致煙熏痕跡最薄處向排煙口方向發(fā)生明顯偏移，影響對起火點的準確判定。 室內(nèi)火源布局為壁面火時，通風使得壁面頂部煙熏痕跡的厚度顯著降低，火源燃燒時間顯著縮短，同時還強化了壁面V型痕跡的輪廓特征：即與自然排煙條件下的痕跡相比，機械通風條件下的壁面V型痕跡輪廓明顯增大，整體微微向排煙口傾斜，辨識起火點更容易。 室內(nèi)火源布局為墻角火時，墻角處的壁面能形成清晰的V形痕跡，易于辨識起火點。由于火源位于模型房間門口的墻角，通風僅能使壁面頂部煙熏痕跡的厚度減小，對燃燒時間和煙氣溫度影響不大�？梢姡绻鹪次恢门R近火場進氣口或排煙口，機械排煙對壁面痕跡的影響并不大。 計算機數(shù)值模擬實驗通過計算煙氣濃度來表征壁面痕跡的分布，實驗精度較高。與實際照片中的煙熏痕跡實驗比較下來，中心火和墻角火的模擬結(jié)果很接近，壁面火的V形痕跡無法準確的用濃度分布圖來表征，故模擬精度較差�？傮w來講，模擬實驗的結(jié)果可靠。
[Abstract]:Smoke trace on wall is an important research content in fire investigation. In some fire sites, the research value of smoke trace on wall becomes particularly important because of the destruction of the surface trace and the residual product of burning in the process of extinguishing the fire.The main reason for the smoke marks of the fire wall is that the free carbon in the fire smoke is absorbed into the wall surface or gap.Therefore, in order to study the formation of smoke traces on the wall, the first step is to study the movement of fire smoke.There are many factors that affect the smoke movement in fire. This paper mainly explores the influence of fire ventilation on the formation law of smoke traces of fire, and through theoretical model analysis, solid model experiment and numerical simulation to study the relevant laws.In this paper, based on the analysis of previous research results, firstly, using point source model theory, parabola is used to characterize the contour curve of the V-shaped smoke mark on the wall.The influence of the relationship between the smoke plume and the wall position of the fire source on the smoke trace of V-type smoke was determined, and the pyramidal busbar of the plume was fitted according to the experimental results.On the basis of this, three kinds of fire sources with different layout were set up in the model room. The changes of smoke traces on the wall of indoor fire were studied by experiment under the condition of natural smoke exhaust and mechanical smoke exhaust.When the layout of indoor fire source is the central fire, the thinnest part of the wall trace should be located directly above the fire source under the condition of natural smoke exhaust.Ventilation reduces the thickness of smoke marks at the top of the wall, shortens the burning time of the fire source, and results in obvious deviation from the thinnest part of the smoke smoke trace to the outlet, which affects the accurate determination of the fire point.When the indoor fire source layout is wall fire, ventilation reduces the thickness of smoke trace at the top of the wall and shortens the burning time of the fire source. At the same time, it also strengthens the contour characteristics of the V-shaped trace on the wall: that is, compared with the trace under the condition of natural smoke exhaust,Under mechanical ventilation, the contour of V-shaped trace on the wall increases obviously, and the whole slightly inclines to the vent, so it is easier to identify the fire point.When the interior fire source layout is corner fire, the wall at the corner can form clear V-shaped trace, and it is easy to identify the fire point.Because the fire source is located in the corner of the door of the model room, ventilation can only reduce the thickness of smoke trace at the top of the wall, and has little effect on the burning time and flue gas temperature.It can be seen that if the source of fire is near the air inlet or exhaust port, the influence of mechanical smoke exhaust on the wall trace is not great.Computer numerical simulation experiments show that the distribution of wall traces is characterized by calculating the smoke concentration, and the experimental accuracy is high.Compared with the smoke trace experiments in the actual photographs, the simulation results of the central fire and the corner fire are very close. The V-shape trace of the wall fire can not be accurately characterized by the concentration distribution map, so the simulation accuracy is poor.In general, the simulation results are reliable.
【學位授予單位】：天津商業(yè)大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU998.12

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