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摘要 本研究是建立一平面火焰爐實驗裝置,用以研究低溫壁面冷卻對層流預混甲烷/空氣火焰結構的影響。實驗方法在定性上,以可見光及schlieren光學觀察火焰在兩平行低溫側壁內的火焰結構。定量上則利用S-type熱電偶作溫度場量測。實驗中將低溫壁面溫度固定為390±10K,甲烷/空氣混合氣進口速度在室溫下固定為0.2m/s,進而改變燃氣當量比及平板間距。結果顯示,預混火焰在兩低溫壁間,會在schlieren影像中產生一類似邊界層區域。且兩低溫壁的間距為10mm時,此類似邊界層厚度較間距為15mm時為大。在兩壁間距為10mm下,Φ=1.0~0.8之間,在垂直低溫壁上段有二次火焰的存在。Φ=1.0~0.45時,沿著低溫壁面有拉伸火焰的產生,且當量比較小的火焰拉伸現象較為強烈。以上火焰拉伸強度,在兩壁間距較小時較為明顯。在Φ略小於0.45時,火焰會產生不穩定震盪而熄滅。當兩壁間距減為7mm時,火焰在點燃後,會迅速傳至爐面附近,並在發生聲響後快速熄滅。 參 考 文 獻 [1] Wichman,I.S.,and Bruneaux,G.,“Head-On Quenching of a Premixed Flame by a Cold Wall,”Combustion and Flame 103: 296-310 (1995). [2] Kim,H.M.,Lee,S.R.,and Chung,S.H., “Numerical Study on the Structure and Extinction of Stretched Lean H2/Air Premixed Flames,” Transport Phenomena in Thermal Engineering,pp.643-647(1993). [3] Westbrook,C.K.,“A Numerical Study of Laminar Wall Quenching,” Combustion and Flame 40:81-99 (1981). [4] Vlachos,D.G.,Schmidt,L.D., and Aris,R., “Ignition and Extinction of Flames Near Surfaces: Combustion of H2 in Air,” Combustion and Flame 95:313-335(1993). [5] Poinsot,T.J.,Haworth,D.C.,and Bruneaux,G.,“Direct Simulation and Modeling of Flame-Wall Interaction for Premixed Turbulent Combustion,” Combustion and Flame 95:118-132 (1993). [6] Hackert,C.L.,Ellzey,J.L.,and Ezekoye,O.A.,“Effects of Thermal Boundary Conditions on Flame Shape and Quenching in Ducts,” Combustion and Flame 112:73-84(1998). [7] Carrier,G.F.,Fendell,F.E.,andFeldman,P.S.,“Laminar Flame Propagation/Quench for a Parallel-Wall Duct,” Twentieth Symposium (International) on Combustion, The Combustion Institute, 1984, pp.67-74. [8] Fairchild,P.W.,Fleeter,R.D.,and Fendell,F.E.,“Raman Spectroscopy Mwasurements of Flame Quenching in a Duct-Type Crevice,” Twentieth Symposium (International) on Combustion, The Combustion Institute, 1984, pp.85-90. [9] Yan Z.,and Holmstedt G.“Three-dimensional Computation of Heat Transfer from Flame Between Vertical Parallel Walls,” Combustion and Flame 117:574-588(1999). [10] Turns,S.R., “An Introduction to Combustion,” McGraw-Hill, Inc.1996. [11] Ezekoye,O.,Greif,R.,and Sawyer,R.F., “Increased Surface Temperature Effects on Wall Heat Transfer during Unsteady Flame Quenching,” Twenty-Fourth Symposium (International) on Combustion, The Combustion Institute, 1992, pp. 1465-1472. [12] Ezekoye,O.A., “Heat Transfer Modeling during Knock and Flame Quenching in an Engine Chamber,” Twenty-Sixth Symposium (International) on Combustion, The Combustion Institute, 1996, pp. 2661-2668. [13] 胡耀仁 “The Quenching Effect of Cold Walls on Steady Laminar Premixed H2/O2 Flame,”國立清華大學動力機械工程學系碩士論文(2000). [14] J.Andrae and P.Bjornbom “Numerical Studies of Wall Effects with Laminar Methane Flames” combustion and Flame 128:165-180(2002). [15] Trevino,C.and Sen,M. Transient Phenomena in Boundary Layer Ignition With Finite Plate Thermal Resistance,Eighteenth Symposium(International) on Combusition,The Combustion Institute, p.1781. [16] Law, C.K and Law, H.K.,Thermal-ignition Analysis in Boundary-Layer Flows. J. Fluid Mech.,92,97(1979). [17] 趙令鈞”Igintion Analysis of Combustible Stagnation-Point Flow” 國立清華大學動力機械工程學系碩士論文(1999). [18] Eckert E.R.G and Goldstein R.J “Measurements in Heat Transfer,” McGraw-Hill, Inc.1976. [19] Egolfopoulos F.N.,Zhang H. and Zhang Z.”Wall Effect on the Propagation and Extinction of Steady, Strained, Laminar Premixed Flames” Combustion and Flame 109:237-252(1997). [20] Kent, A.”A Noncatalytic Coating for Platinum-Rhodium Thermocouples” Combustion and Flame 14:279-282(1970).
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