氮气稀释气对天然气燃烧特性的影响
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摘要
为获得氮气稀释气对天然气燃烧特性的影响规律,在定容燃烧反应器中对不同当量比与初始压力下天然气的火焰传播特性、燃烧稳定性及燃烧特性进行了试验测试,并分析了氮气稀释度对天然气火焰传播特性、燃烧稳定性及燃烧特性的影响规律。研究结果表明:随着初始压力与氮气稀释度的升高,火焰前锋面将出现细小裂纹,火核逐渐向定容燃烧反应器上部漂移,火焰稳定性变差;随着初始压力的提高,马克斯坦长度明显变短,火焰稳定性变差,无拉伸火焰传播速度与层流燃烧速度明显降低,但最大燃烧压力显著升高。随着当量比的提高,层流燃烧速度与最大燃烧压力出现先增加后降低的趋势,两者的最大值出现在当量比为1.0时。马克斯坦长度随氮气稀释度的增加逐渐变短,表明火焰逐渐趋于不稳定;同时,无拉伸火焰传播速度、层流燃烧速度与最大燃烧压力随氮气稀释度的增加显著降低。
In order to gain the effects of diluent nitrogen gas on the combustion characteristics of natural gas, flame development characteristics, combustion stability and combustion characteristics of natural gas at different equivalence ratio and initial pressure were experimental studied in a constant volume combustion bomb, and the effects of dilution ratio of nitrogen on the flame development characteristics, combustion stability and combustion characteristics of natural gas were analyzed. The results show that micro-cracks appear on the flame front, flame core drifts to the upside of the constant volume combustion bomb and flame instability is established with the initial pressure and nitrogen dilution ratio increasing. The instability of the flame front increases, which is established by decreased Markstein length, and unstretched laminar flame propagation velocity and laminar burning velocity decrease and the maximum combustion pressure increases with the increase of initial pressure of the natural gas. At the same time, with the equivalence ratio increasing, the laminar burning velocity and the maximum combustion pressure illustrate an increase initially and then decreases gradually and the maximum values are measured at the equivalence ratio is 1.0. Furthermore, Markstein length is decreasedand flame instability is established with the increase of dilution ratio of nitrogen. Also unstretched laminar flame propagation velocity, laminar burning velocity and the maximum combustion pressure decrease distinctly with the increase of dilution ratio of nitrogen.
In order to gain the effects of diluent nitrogen gas on the combustion characteristics of natural gas, flame development characteristics, combustion stability and combustion characteristics of natural gas at different equivalence ratio and initial pressure were experimental studied in a constant volume combustion bomb, and the effects of dilution ratio of nitrogen on the flame development characteristics, combustion stability and combustion characteristics of natural gas were analyzed. The results show that micro-cracks appear on the flame front, flame core drifts to the upside of the constant volume combustion bomb and flame instability is established with the initial pressure and nitrogen dilution ratio increasing. The instability of the flame front increases, which is established by decreased Markstein length, and unstretched laminar flame propagation velocity and laminar burning velocity decrease and the maximum combustion pressure increases with the increase of initial pressure of the natural gas. At the same time, with the equivalence ratio increasing, the laminar burning velocity and the maximum combustion pressure illustrate an increase initially and then decreases gradually and the maximum values are measured at the equivalence ratio is 1.0. Furthermore, Markstein length is decreasedand flame instability is established with the increase of dilution ratio of nitrogen. Also unstretched laminar flame propagation velocity, laminar burning velocity and the maximum combustion pressure decrease distinctly with the increase of dilution ratio of nitrogen.
引文
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[2] ROJO C,VANCASSEL X,MIRABEL P,et al.Impact of alternative jet fuels on aircraft-induced aerosols [J].Fuel,2015,144:335-341.
[3] BERGTHORSON J M,THOMSON M J.A review of the combustion and emissions properties of advanced transportation biofuels and their impact on existing and future engines [J].Renewable and Sustainable Energy Reviews,2015,42:1393-1417.
[4] 苏亚欣,汪文辉,杨翔翔.旋流燃烧器螺旋伸展长度对高温空气燃烧特性的影响 [J].热科学与技术,2011,10(3):231-236.SU Ya-xin,WANG Wen-hui,YANG Xiang-xiang.Effect of stretch length of swirling burner on high temperature air combustion performance [J].Journal of Thermal Science and Technology,2011,10(3):231-236.(in Chinese)
[5] 董素荣,刘鹏宇,刘瑞琳,等.煤基混合燃料对柴油机燃烧与排放特性影响的研究 [J].热科学与技术,2016,15(5):391-396.DONG Su-rong,LIU Peng-yu,LIU Rui-lin,et al.Experimental research on effect of coal-based hybrid fuel on combustion and emission characteristics of diesel engine [J].Journal of Thermal Science and Technology,2016,15(5):391-396.(in Chinese)
[6] LADOMMATOS N,ABDELHALIM S,ZHAO H.Control of oxides of nitrogen from diesel engines using diluents while minimizing the impact on particulate pollutants [J].Applied Thermal Engineering,1998,18(11):936-980.
[7] ZHENG M,READER G,HAWLEY J.Diesel engine exhaust gas recirculation:A review on advanced and novel concepts [J].Energy Conversion and Management,2004,45(6):883-900.
[8] ABD-ALLA G.Using exhaust gas recirculation in internal combustion engines:A review [J].Energy Conversion and Management,2002,43(8):1027-1042.
[9] ELIA M,ULINSKI M,METGHALCHI M.Laminar burning velocity of methane-air-diluent mixtures [J].Journal of Engineering for Gas Turbines and Power,2001,123:190-196.
[10] GU X J,HAQ M Z,LAWES M,et al.Laminar burning velocity and markstein lengths of methane-air mixtures [J].Combustion and Flame,2000,121:41-58.
[11] HAN P F,CHECKEL M D,FLECK B A,et al.Burning velocity of methane/diluent mixture with reformer gas addition [J].Fuel,2007,86:585-596.
[12] HU E J,JIANG X,HUANG Z H,et al.Numerical study on the effects of diluents on the laminar burning velocity of methane-air mixtures [J].Energy & Fuels,2012,26:4242-4252.
[13] LIAO S Y,JIANG D M,HUANG Z H,et al.Laminar burning velocities for mixtures of methanol and air at elevated temperatures [J].Energy Conversion and Management,2007,48:857-863.
[14] 曾文,陈欣,马洪安,等.RP-3航空煤油层流燃烧特性的实验 [J].航空动力学报,2015,30(12):2888-2896.ZENG Wen,CHEN Xin,MA Hong-an,et al.Experiment study on laminar burning characteristics of RP-3 kerosene [J].Journal of Aerospace Power,2015,30(12):2888-2896.(in Chinese)
[15] BRADLEY D,GASKELL P H,GU X J.Burning velocities,markstein lengths,and flame quenching for spherical methane-air flames:A computational study [J].Combustion and Flame,1996,104(1-2):176-198.
[16] HUANG Z H,WANG Q,YU J R,et al.Measurement of laminar burning velocity of dimethyl ether-air premixed mixtures [J].Fuel,2007,86(15):2360-2366.
[17] BURKE M P,CHEN Z,JU Y,et al.Effect of cylindrical confinement on the determination of laminar flame speeds using outwardly propagating flames [J].Combustion and Flame,2009,156(4):771-779.
[18] HU E J,HUANG Z H,HE J J,et al.Experimental and numerical study on laminar burning characteristics of premixed methane-hydrogen-air flames [J].International Journal of Hydrogen and Energy,2009,34(11):876-4888.