DME/O_2/N_2预混冷焰的着火与熄火研究
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摘要
本文通过数值模拟研究了DME/O_2/N_2预混冷焰的着火和熄火特性,并与其热焰的性质进行了对比。研究使用了全混流反应器(PSR)和对冲火焰两个模型。PSR研究结果表明与热焰相比冷焰着火和熄火对当量比的变化并不敏感。通过对冲预混冷焰的计算发现冷焰燃烧的温度为700～760 K,在当量比为0.6～1.4范围内,冷焰熄灭拉伸率和熄灭极限火焰温度都随着当量比单调增加,冷焰熄灭拉伸率变化率仅为-20%,远小于热焰熄灭拉伸率的变化率。
The ignition and extinction characteristics of premixed DME/O_2/N_2 cool flames were numerically investigated and compared with those of hot flames.The perfectly-stirred reactor(PSR)and counterflow flame model were used in the present study.PSR analysis demonstrated a weaker dependence of cool flame ignition and extinction on equivalence ratio than those of hot flame.The counterflow cool flame computation showed that the cool flame temperature was 700～760 K.The extinction stretch rate and the temperature of the cool flame monotonically increased as the equivalence ratio increased from 0.6 to 1.4.In the equivalence ratio range from 0.6 to 1.4,the relative change of the extinction stretch rate of the cool flame was more than-20%,much smaller than that of the hot flame.
The ignition and extinction characteristics of premixed DME/O_2/N_2 cool flames were numerically investigated and compared with those of hot flames.The perfectly-stirred reactor(PSR)and counterflow flame model were used in the present study.PSR analysis demonstrated a weaker dependence of cool flame ignition and extinction on equivalence ratio than those of hot flame.The counterflow cool flame computation showed that the cool flame temperature was 700～760 K.The extinction stretch rate and the temperature of the cool flame monotonically increased as the equivalence ratio increased from 0.6 to 1.4.In the equivalence ratio range from 0.6 to 1.4,the relative change of the extinction stretch rate of the cool flame was more than-20%,much smaller than that of the hot flame.
引文
[1]Davy H.Some New Experiments and Observations on the Combustion of Gaseous Mixtures,with an Account of a Method of Preserving a Continued Light in Mixtures of Inflammable Gases and Air without Flame[J].Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London,1817,107:77-85
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[17]Tsuji H.Counterflow Diffusion Flames[J].Progress in Energy&Combustion Science,1982,8(2):93-119
[18]Zhang Y,Shen W,Zhang H,et al.Effects of Inert Dilution on the Propagation and Extinction of Lean Premixed Syngas/Air Flames[J].Fuel,2015,157:115-121
[19]Zhang Y,Shang R,Shen W,et al.Extinction Limit and near-Limit Kinetics of Lean Premixed Stretched H_2-CoAir Flames[J].International Journal of Hydrogen Energy,2016,41(39):17687-17694
[20]Kee R J,Rupley F M,Miller J A.CHEMKIN-II:A Fortran Chemical Kinetics Package for the Analysis of GasPhase Chemical Kinetics[R].Sandia National Laboratories,1989,SAN89-8009
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[24]Zhao Z,Chaos M,Kazakov A,et al.Thermal Decomposition Reaction and a Comprehensive Kinetic Model of Dimethyl Ether[J].International Journal of Chemical Kinetics,2008,40(1):1-18
[25]Wang Y L,Holley A T,Ji C,et al.Propagation and Extinction of Premixed Dimethyl-Ether/Air Flames[J].Proceedings of the Combustion Institute,2009,32(1):1035-1042
[2]Griffiths J F,Scott S K.Thermokinetic Interactions:Fundamentals of Spontaneous Ignition and Cool Flames[J].Progress in Energy&Combustion Science,1987,13(3):161-197
[3]Ju Y,Sun W,Burke M P,et al.Multi-Timescale Modeling of Ignition and Flame Regimes of N-Heptane-Air Mixtures near Spark Assisted Homogeneous Charge Compression Ignition Conditions[J].Proceedings of the Combustion Institute,2011,33(1):1245-1251
[4]Dai P,Chen Z,Chen S,et al.Numerical Experiments on Reaction Front Propagation in N-Heptane/Air Mixture with Temperature Gradient[J].Proceedings of the Combustion Institute,2015,35(3):3045-3052
[5]Sun W,Sang H W,Gou X,et al.Multi-Scale Modeling of Dynamics and Ignition to Flame Transitions of High Pressure Stratified N-Heptane/Toluene Mixtures[J].Proceedings of the Combustion Institute,2015,35(1):1049-1056
[6]Sun W,Sang H W,Ju Y.In Situ Plasma Activated Low Temperature Chemistry and the S-Curve Transition in Dme/Oxygen/Helium Mixture[J].Combustion&Flame,2014,161(8):2054-2063
[7]Ju Y,Sun W.Plasma Assisted Combustion:Dynamics and Chemistry[J].Progress in Energy&Combustion Science,2015,48:21-83
[8]Reuter C B,Sang H W,Ju Y.Experimental Study of the Dynamics and Structure of Self-Sustaining Premixed Cool Flames Using a Counterflow Burner[J].Combustion&Flame,2016,166:125-132
[9]Reuter C B,Sang H W,Ju Y.Flame Structure and Ignition Limit of Partially Premixed Cool Flames in a Counterflow Burner[J].Proceedings of the Combustion Institute,2017,36:1513-1522
[10]Ju Y,Reuter C B,Won S H.Numerical Simulations of Premixed Cool Flames of Dimethyl Ether/Oxygen Mixtures[J].Combustion and Flame,2015,162(10):3580-3588
[11]Ju Y.On the Propagation Limits and Speeds of Premixed Cool Flames at Elevated Pressures[J].Combustion and Flame,2017,178:61-69
[12]Zhao P,Liang W,Deng S,et al.Initiation and Propagation of Laminar Premixed Cool Flames[J].Fuel,2016,166:477-487
[13]Zhang W,Faqih M,Gou X,et al.Numerical Study on the Transient Evolution of a Premixed Cool Flame[J].Combustion and Flame,2018,187:129-136
[14]Liang W,Law C K.Extended Flammability Limits of NHeptane/Air Mixtures with Cool Flames[J].Combustion and Flame,2017,185:75-81
[15]Glarborg P,Kee R J,Grcar J F,et al.PSR:A Fortran Program for Modeling Well-Stirred Reactors[R].Sondia National Laboratories,1986,SAND86—8209
[16]Oberlack M,Arlitt R,Peters N.On Stochastic Damkohler Number Variations in a Homogeneous Flow Reactor[J].Combustion Theory and Modelling,2000,4(4):495-509
[17]Tsuji H.Counterflow Diffusion Flames[J].Progress in Energy&Combustion Science,1982,8(2):93-119
[18]Zhang Y,Shen W,Zhang H,et al.Effects of Inert Dilution on the Propagation and Extinction of Lean Premixed Syngas/Air Flames[J].Fuel,2015,157:115-121
[19]Zhang Y,Shang R,Shen W,et al.Extinction Limit and near-Limit Kinetics of Lean Premixed Stretched H_2-CoAir Flames[J].International Journal of Hydrogen Energy,2016,41(39):17687-17694
[20]Kee R J,Rupley F M,Miller J A.CHEMKIN-II:A Fortran Chemical Kinetics Package for the Analysis of GasPhase Chemical Kinetics[R].Sandia National Laboratories,1989,SAN89-8009
[21]Shan R,Lu T.Ignition and Extinction in Perfectly Stirred Reactors with Detailed Chemistry[J].Combustion and Flame,2012,159(6):2069-2076
[22]Nishioka M,Law C,Takeno T.A Flame-Controlling Continuation Method for Generating S-Curve Responses with Detailed Chemistry[J].Combustion and Flame,1996,104(3):328-342
[23]Lutz A E,Kee R J,Grcar J F,et al.Oppdif:A Fortran Program for Computing Opposed-Flow Diffusion Flames[R].Sandia National Laboratories,1997,SAND96-8243
[24]Zhao Z,Chaos M,Kazakov A,et al.Thermal Decomposition Reaction and a Comprehensive Kinetic Model of Dimethyl Ether[J].International Journal of Chemical Kinetics,2008,40(1):1-18
[25]Wang Y L,Holley A T,Ji C,et al.Propagation and Extinction of Premixed Dimethyl-Ether/Air Flames[J].Proceedings of the Combustion Institute,2009,32(1):1035-1042