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題 名 | 具震波之二維冷熱氣動流場之數值模擬=Numerical Simulation of Two-Dimensional Nonreacting and Reacting Gasdynamic Flows with Shocks |
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作 者 | 劉通敏; 黃柏文; 陳聰堅; | 書刊名 | 燃燒學會會刊 |
卷 期 | 7:2=23 1998.06[民87.06] |
頁 次 | 頁22-27 |
分類號 | 446.11 |
關鍵詞 | Godunov數值法; 震波管; 前向階梯; 剪層; 渦流結構; |
語 文 | 中文(Chinese) |
中文摘要 | 本文以數值模擬的方式,計算一維震波管流場、具前向階梯之二維超音速流場及 剪層之冷、熱流場。 本研究採用有限體積法,配合修正型 Godunov 數值法,來求解二維守 恆 Euler 及 Navier-Stokes 方程組。透過數值實驗的方式,顯示文中所採用之數值法具有 捕捉氣動流場中震波、膨脹波及不連續面的能力,且能解析此些波動間交互作用下之流場結 構。在剪層之冷、熱流場研究當中發現,燃燒效應會降低渦流結構之渦度,而流場中無論是 膨脹波或震波之衝擊,均會造成渦流結構之增長。由熱流場之瞬時溫度場及各組成之質量分 率分佈顯示,化學反應多發生於渦流結構當中。 |
英文摘要 | The behaviors of downward flame spread over the solid fuels of different thickness are analyzed numberically in this paper. A 2-D solid phase model is developed and coupled with the 2-D gas phase combustion model to investigate the thickness effects on flame spread characteristics and their respective controlling mechanisms under a natural convective condition. Accordingly, the parametic study is based on change of fuel thickness, varied from lmm to 10mm, Excellent agreements are found between the numerical and related experimental results. The thickness can be categorized into four regions according to corresponding flame spread behaviors. Regions (Ⅰ ) is the thermally-thin region (1.0mm ≦δ�� <1.5mm), whose flame spread rate is inversely proportional to fuel thickness. Region (Ⅱ )is the transition region (1.5mm ≦δ�N≦ 2.2mm), where the two-dimensional feature start to become apparent. Region (Ⅲ ), is the thermally-thick region (2.2 mm< δ�N≦ 7 mm), where the flame spread rate decreases as the fuel thicnkness increases but with a decreasing descendent rate. In this region, the preheat lenght in solid phase is found greater than that in gas phase, indicating that the solid conduction plays a crucial role for flame spread over thick fuel. We also find that the total heat flux across the half fuel thickness via solid conduction at flame leading edge is ranged from 18% to 36% of the one from gas phase ahead of the flame leading edge. In the previous two regions, this ratio is under 14%. The Region (Ⅳ )is an unstable region. (δ�N≧ 7.5 mm),where a sudden drop in flame spread rate comparing with region (Ⅲ ) is found. Finally, the detailed flame structures of δ�N =4mm in thermally-thick region are given to illustrate the interaction between the gas phase combustion and fuel pyrolvsis |
本系統中英文摘要資訊取自各篇刊載內容。