臺灣博碩士論文加值系統

此研究在於探討順流火焰在薄燃料上穩定傳播之現象。實驗選用三種參數，分析參數對火焰在薄燃料(紙)上傳播所造成的影響。分別為傾斜角度；燃料寬度以及面積密度。傾斜角度設定與重力方向的夾角，角度範圍在0度至75度之間，以15度為一區間。發現傾斜角度越大，火焰長度縮短，火焰傳播速率下降。燃料寬度選用1公分、1.25公分以及1.5公分，發現火焰傳播速率隨寬度增加而增加。面積密度選用0.0128(樣本A)、0.0061(樣本B)以及0.0028(樣本C)g/cm2 ，火焰傳播速率隨面積密度增加而減小。
模擬部分使用二維的穩態向上傳播火焰模型，忽略氣相輻射效應，探討薄固體燃料在低速浮力流場中，順流火焰在傾斜的薄燃料上傳播之現象，以及火焰傳播速率的比較。發現了當傾斜角度(燃料平行重力場方向為0度)越大時，火焰長度呈現對稱的現象，隨著氣態反應速率下降，火焰長度不對稱情形明顯出現。當傾斜角度大於30度時，火焰長度及火焰傳播速率明顯下降。當重力場越大時，火焰呈現細長結構，火焰傳播速率越快。當重力場下降，火焰長度縮短，火焰傳播速率較慢。在熄滅極限的參數模擬中，隨著傾斜角度越大，火焰的熄滅極限範圍變小。在較高重力場大小下，氣體反應速率範圍呈現震盪的情形，火焰傳播速率無法達到穩態。低重力場下，火焰穩定區的氣態反應速率較小，無法支持火焰傳播而導致熄滅。

The upward spreading flames are studied by experiments and numerical simulations in this study. In the experiments, flame spread on several narrow sample widths (1cm 1.25cm and 1.5cm) are tested; for the numerical simulation, a two-dimensional model is used (infinite wide width) to simulate the stead flame propagation. The effects of the inclined angle and area density of sample paper on flame shape and spread rate are investigated.
From the experiments, it is found that the flame spread rate increases as sample width increases. In this study, several area densities, 0.0128g/cm2, 0.0061g/cm2 and 0.0028g/cm2 are also test in the experiments. The experimental data shows that the flame spread rate decreases as the area density increases. In addition, as the inclined angle ( 0-75 degree from the vertical) is increased, the flame length becomes shorter and the flame spread rate becomes slower.
A two-dimensional model without gas-phase radiation is used to simulate the steady upward propagating flame. The effects of inclined angle and gravity level are tested. Similar to the experimental results, the flame length and spread rate decreases with the increase in inclined angle. As the gravity level is increase, the flame length increases. A low-gravity flame quenching limit can be found in this model. At high gravities, the oscillating and pulsating flames are simulated and no steady spreading flame exists. At low gravity, the convection heat to solid decreases and eventually leads to flame extinguishing.

目錄 vi
圖目錄 viii
表目錄 xi
第一章 序論 1
1.1 前言 1
1.2 文獻回顧 2
1.3 研究目的 13
第二章 實驗設備及方法 15
2.1 實驗儀器與設備 15
2.2 量測穩態火焰傳播速率及誤差 18
2.3 實驗規劃 20
第三章 數值模型 22
3.1數學模型 23
3.2 數值方法 26
第四章 結果與討論 27
4.1燃料樣本角度影響 29
4.2燃料樣本寬度的影響 31
4.3燃料樣本面積密度的影響 33
4.4無因次重力場大小對火焰傳播速率的影響 33
4.5模擬角度對火焰結構之影響 37
4.6模擬面積密度對火焰結構之影響 39
4.7模擬重力場對火焰結構的影響 40
4.8模擬火焰熄滅極限 41
第五章 結論 43
參考文獻 45

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