本文選題：地表火蔓延 + 點火源引燃　； 參考：《中國科學技術大學》2017年碩士論文

【摘要】：森林地表火蔓延是森林火災最主要的形式。本文主要研究點火源引燃條件下坡度和燃料載荷對火蔓延過程的影響。在變坡度火蔓延實驗臺上,用刨花絲為燃料,分別開展變化7個坡度角和3種燃料載荷的點火源引燃火蔓延實驗研究。重點分析火焰幾何參數(shù)(火線夾角,火焰傾斜角,火焰長度)、火線形狀、全局火蔓延速率、局部火蔓延速率以及火前鋒阻滯時間的變化規(guī)律。上坡火線夾角、火焰傾斜角隨坡度角的增大而減小,火焰長度隨坡度角的增大而增大。平坡條件下,火線呈規(guī)則的圓形,阻滯時間高于上坡火前鋒的阻滯時間。坡度條件下,火線形狀會呈淚滴狀,當坡度角低于20°時,上坡火蔓延速率隨坡度角緩慢增大;當坡度角高于20°時,上坡火蔓延速率隨坡度角迅速增大。上坡火蔓延表現(xiàn)出整體穩(wěn)定和局部波動的特征。自引燃點向下、左、右的火蔓延速率隨坡度角的增大震蕩變化。上坡火焰長度隨著載荷的增大而增大,引燃點位置向上、下、左、右的火蔓延速率均隨載荷的增大而增大。高坡度條件下(22.5～30°)上坡火蔓延速率隨著載荷增大的速率,高于低坡度條件(O～20°)。除平坡外,任意坡度下4個方向上的火前鋒平均阻滯時間均隨載荷的增大而增大。上坡火蔓延過程中,隨坡度角增加,火焰長度增長且火焰傾斜角增大,火焰對燃料的輻射傳熱增強,引發(fā)了火蔓延速率的增大。
[Abstract]:The spread of forest surface fire is the main form of forest fire. In this paper, the effects of slope and fuel load on the process of fire propagation are studied. In this paper, the flame propagation of ignited sources with 7 slope angles and 3 kinds of fuel loads were studied by using planed wire as fuel on the fire spread test bench with variable slope. The variation of the geometric parameters of the flame (the angle between the lines of fire, the angle of the flame inclination, the length of the flame, the shape of the line of fire, the global fire spread rate, the local fire spread rate and the fire front block time) are analyzed. The angle between the fire line and the slope angle of the fire line decreases with the increase of the slope angle, and the flame length increases with the increase of the slope angle. Under the condition of flat slope, the fire line is regular and circular, and the blocking time is higher than that of the fire front on the slope. When the slope angle is lower than 20 擄, the fire spread rate increases slowly with the slope angle, and when the slope angle is higher than 20 擄, the fire spread rate increases rapidly with the slope angle. The upslope fire spread shows the characteristics of global stability and local fluctuation. The fire spread rate varies with the increase of slope angle. The flame length of the slope increases with the increase of the load, and the fire spread rate increases with the increase of the load at the position of ignition point upward, down, left and right. Under high slope condition, the rate of fire spread on the slope is higher than that on the low slope condition by 20 擄with the increase of load. With the exception of flat slope, the average block time of fire front increases with the increase of load at any slope in four directions. In the process of slope fire spread, the length of flame increases and the angle of inclination increases with the increase of slope angle, and the radiative heat transfer between flame and fuel increases, which leads to the increase of fire spread rate.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S762

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本文編號：1872490