基于发动机非正常燃烧的湍流火焰-冲击波相互作用的实验研究
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摘要
爆震、超级爆震等非正常燃烧现象是限制小型强化点燃式发动机热效率进一步提升的突出瓶颈。爆震或超级爆震发生时总会伴随着湍流火焰-冲击波的相互作用,因此对湍流火焰-冲击波的相互作用的研究是揭示其机理的关键。本文通过在可视化定容燃烧弹内安装孔板实现火焰过孔板加速并产生冲击波,并通过改变初始热力学条件和孔板的参数,来实现不同强度的湍流火焰和冲击波及其相互作用过程。基于该燃烧装置开展了火焰加速、冲击波的形成以及湍流火焰-冲击波相互作用导致不同燃烧模式的研究。根据燃烧室末端火焰传播和压力振荡情况,总结出5种燃烧模式,其中发生自燃的燃烧模式的压力振荡幅值均超过4.5MPa,是未发生自燃时的4~40倍。因此,湍流火焰-冲击波相互作用对燃烧压力振荡具有重要影响。
Abnormal combustion phenomena like knock or super-knock are inherent constraint limiting the performance and efficiency of downsized spark ignition(SI)engines.Essentially,engine knock or super-knock is always accompanied by the interactions of turbulent flames and shock waves,as well as rapid chemical energy release.Thus,it is of great significance to investigate the interactions of turbulent flame and shock waves which are the key to reveal the mechanism of knock and super-knock.The major objective of the present work is to experimentally investigate the process of flame acceleration,shock wave formation and interactions of turbulent flame and shock wave in a newly designed constant volume combustion bomb(CVCB)mounted with a perforated plate.In the CVCB,the perforated plate is used to achieve flame acceleration and produce turbulent flame and shock wave.High-speed Schlieren photography was employed to capture the interactions of turbulent flame and shock wave.Hydrogen-air mixture was chosen as the test fuel due to its fast flame propagation velocity and easiness to form obvious shock wave ahead of the flame front.Interactions of turbulent flame and shock wave at different levels could be obtained by changing the initial thermodynamic conditions(including initial pressure and equivalence ratio)and parameters of the perforated plate(including hole size and porosity).Flame acceleration,formation of shock wave and flame-shock wave interactions are discussed in this paper.Depending on the interactions of turbulent flame and shock wave,five combustion modes are obtained by experiments,such as normal combustion,periodically decelerating combustion,oscillating combustion,flame-front autoiginiton and end-gas autoiginiton.The maximum amplitude of the pressure oscillation at combustion models with autoiginiton exceeded 4.5 MPa,4~40 timesgreater than those without ignition.Therefore,autoiginiton caused by the interactions of turbulent flame and shock wave is the root cause of the intense pressure oscillation in the combustion chamber.
Abnormal combustion phenomena like knock or super-knock are inherent constraint limiting the performance and efficiency of downsized spark ignition(SI)engines.Essentially,engine knock or super-knock is always accompanied by the interactions of turbulent flames and shock waves,as well as rapid chemical energy release.Thus,it is of great significance to investigate the interactions of turbulent flame and shock waves which are the key to reveal the mechanism of knock and super-knock.The major objective of the present work is to experimentally investigate the process of flame acceleration,shock wave formation and interactions of turbulent flame and shock wave in a newly designed constant volume combustion bomb(CVCB)mounted with a perforated plate.In the CVCB,the perforated plate is used to achieve flame acceleration and produce turbulent flame and shock wave.High-speed Schlieren photography was employed to capture the interactions of turbulent flame and shock wave.Hydrogen-air mixture was chosen as the test fuel due to its fast flame propagation velocity and easiness to form obvious shock wave ahead of the flame front.Interactions of turbulent flame and shock wave at different levels could be obtained by changing the initial thermodynamic conditions(including initial pressure and equivalence ratio)and parameters of the perforated plate(including hole size and porosity).Flame acceleration,formation of shock wave and flame-shock wave interactions are discussed in this paper.Depending on the interactions of turbulent flame and shock wave,five combustion modes are obtained by experiments,such as normal combustion,periodically decelerating combustion,oscillating combustion,flame-front autoiginiton and end-gas autoiginiton.The maximum amplitude of the pressure oscillation at combustion models with autoiginiton exceeded 4.5 MPa,4~40 timesgreater than those without ignition.Therefore,autoiginiton caused by the interactions of turbulent flame and shock wave is the root cause of the intense pressure oscillation in the combustion chamber.
引文
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[14]Agarwal A K,Chaudhury V H.Spray characteristics of biodiesel/blends in a high pressure constant volume spray chamber[J].Experimental thermal and fluid Science,2012,42:212-218.
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[16]Xiao H,Houim R W,Oran E S.Formation and evolution of distorted tulip flames[J].Combustion and Flame,2015,162(11):4084-4101.
[17]Xiao H,Makarov D,Sun J,et al.Experimental and numerical investigation of premixed flame propagation with distorted tulip shape in a closed duct[J].Combustion&Flame,2012,159(4):1523-1538.
[18]Oppenheim A K,Soloukhin R I.Experiments in gasdynamics of explosions[J].Annual Review of Fluid Mechanics,1973,5(1):31-58.
[19]Lee J H S,Moen I O.The mechans of transition from deflagration to detonation in vapor cloud explosions[J].Progress in Energy and Combustion Science,1980,6(4):359-389.
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[25]Darrieus G.Propagation d’un front de flamme[J].La Technique Moderne,1938,30:18.
[26]Lipatnikov A N,Chomiak J.Molecular transport effects on turbulent flame propagation and structure[J].Progress in Energy and Combustion Science,2005,31(1):1-73.
[27]Wei H,Zhao J,Zhou L,et al.Effects of the equivalence ratio on turbulent flame-shock interactions in a confined space[J].Combustion and Flame,2017,186:247-262.
[28]Bychkov V,Valiev D,Eriksson L E.Physical mechanism of ultrafast flame acceleration[J].Physical Review Letters,2008,101(16):164501.
[29]Liu F,McIntosh A C,Brindley J.A numerical investigation of Rayleigh-Taylor effects in pressure wave-premixed flame interactions[J].Combustion Science and Technology,1993,91(4-6):373-386.
[30]Law C K,Jomaas G,Bechtold J K.Cellular instabilities of expanding hydrogen/propane spherical flames at elevated pressures:theory and experiment[J].Proceedings of the Combustion Institute,2005,30(1):159-167.
[31]Wu F,Jomaas G,Law C K.An experimental investigation on self-acceleration of cellular spherical flames[J].Proceedings of the Combustion Institute,2013,34(1):937-945.
[32]王保国,刘淑艳,黄伟光.气体动力学[M].北京:北京理工大学出版社,2005.
[33]Livengood J C,Wu P C.Correlation of autoignition phenomena in internal combustion engines and rapid compression machines[C]//Symposium(International)on combustion.Elsevier,1955,5(1):347-356.
[34]Winklhofer E,Hirsch A,Kapus P,et al.TC GDI engines at very high power density—irregular combustion and thermal risk[R].SAE Technical Paper,2009.
[35]Kalghatgi G T,Bradley D,Andrae J,et al.The nature of‘superknock’and its origins in SI engines[C]//Proc Conf on Internal Combustion Engines:Performance,Fuel Economy and Emissions,London,UK,2009.
[36]Yu H,Chen Z.End-gas autoignition and detonation development in a closed chamber[J].Combustion and Flame,2015,162(11):4102-4111.
[37]Wei H,Gao D,Zhou L,et al.Different combustion modes caused by flame-shock interactions in a confined chamber with a perforated plate[J].Combustion and Flame,2017,178:277-285.
[2]Heywood J B.Internal combustion engine fundamentals[M].New York:Mcgraw-hill,1988.
[3]Inoue T,Inoue Y,Ishikawa M.Abnormal combustion in a highly boosted SI engine-the occurrence of Super Knock[R].SAE Technical Paper,2012.
[4]Attard W P,Toulson E,Watson H,et al.Abnormal combustion including mega knock in a 60%downsized highly turbocharged PFI engine[R].SAE Technical Paper,2010.
[5]Buerle B,Hoffmann F,Behrendt F,et al.Detection of hot spots in the end gas of an internal combustion engine using twodimensional LIF of formaldehyde[C]//Symposium(International)on Combustion.Elsevier,1994,25(1):135-141.
[6]Kawahara N,Tomita E.Visualization of auto-ignition and pressure wave during knocking in a hydrogen spark-ignition engine[J].International Journal of Hydrogen Energy,2009,34(7):3156-3163.
[7]Ciccarelli G,Dorofeev S.Flame acceleration and transition to detonation in ducts[J].Progress in Energy and Combustion Science,2008,34(4):499-550.
[8]Bradley D,Cresswell T M,Puttock J S.Flame acceleration due to flame-induced instabilities in large-scale explosions[J].Combustion and Flame,2001,124(4):551-559.
[9]Takeuchi K,Fujimoto K,Hirano S,et al.Investigation of engine oil effect on abnormal combustion in turbocharged direct injection-spark ignition engines[J].SAE International Journal of Fuels and Lubricants,2012,5(2012-01-1615):1017-1024.
[10]Qi Y,Wang Z,Wang J,et al.Effects of thermodynamic conditions on the end gas combustion mode associated with engine knock[J].Combustion and Flame,2015,162(11):4119-4128.
[11]Robert A,Richard S,Colin O,et al.LES study of deflagration to detonation mechanisms in a downsized spark ignition engine[J].Combustion and Flame,2015,162(7):2788-2807.
[12]Luo X,Teng H,Hu T,et al.An experimental investigation on low speed pre-ignition in a highly boosted gasoline direct injection engine[J].SAE International Journal of Engines,2015,8(2015-01-0758):520-528.
[13]Wang Z,Qi Y,He X,et al.Analysis of pre-ignition to superknock:hotspot-induced deflagration to detonation[J].Fuel,2015,144:222-227.
[14]Agarwal A K,Chaudhury V H.Spray characteristics of biodiesel/blends in a high pressure constant volume spray chamber[J].Experimental thermal and fluid Science,2012,42:212-218.
[15]Clarke A,Stone R,Beckwith P.Measuring the laminar burning velocity of methane/diluent/air mixtures within a constant-volume combustion bomb in a micro-gravity environment[J].Journal of the Institute of Energy,1995,68(476):130-136.
[16]Xiao H,Houim R W,Oran E S.Formation and evolution of distorted tulip flames[J].Combustion and Flame,2015,162(11):4084-4101.
[17]Xiao H,Makarov D,Sun J,et al.Experimental and numerical investigation of premixed flame propagation with distorted tulip shape in a closed duct[J].Combustion&Flame,2012,159(4):1523-1538.
[18]Oppenheim A K,Soloukhin R I.Experiments in gasdynamics of explosions[J].Annual Review of Fluid Mechanics,1973,5(1):31-58.
[19]Lee J H S,Moen I O.The mechans of transition from deflagration to detonation in vapor cloud explosions[J].Progress in Energy and Combustion Science,1980,6(4):359-389.
[20]Oran E S,Gamezo V N.Origins of the deflagration-to-detonation transition in gas-phase combustion[J].Combustion and Flame,2007,148(1):4-47.
[21]Ciccarelli G,Dorofeev S.Flame acceleration and transition to detonation in ducts[J].Progress in Energy and Combustion Science,2008,34(4):499-550.
[22]Dorofeev S B.Flame acceleration and explosion safety applications[J].Proceedings of the Combustion Institute,2011,33(2):2161-2175.
[23]Wei H,Xu Z,Zhou L,et al.Effect of initial pressure on flameshock interaction of hydrogen-air premixed flames[J].International Journal of Hydrogen Energy,2017,42(17):12657-12668.
[24]Landau L D.On the theory of slow combustion[J].Acta physicochim,URSS,1944,19(1):77-85.
[25]Darrieus G.Propagation d’un front de flamme[J].La Technique Moderne,1938,30:18.
[26]Lipatnikov A N,Chomiak J.Molecular transport effects on turbulent flame propagation and structure[J].Progress in Energy and Combustion Science,2005,31(1):1-73.
[27]Wei H,Zhao J,Zhou L,et al.Effects of the equivalence ratio on turbulent flame-shock interactions in a confined space[J].Combustion and Flame,2017,186:247-262.
[28]Bychkov V,Valiev D,Eriksson L E.Physical mechanism of ultrafast flame acceleration[J].Physical Review Letters,2008,101(16):164501.
[29]Liu F,McIntosh A C,Brindley J.A numerical investigation of Rayleigh-Taylor effects in pressure wave-premixed flame interactions[J].Combustion Science and Technology,1993,91(4-6):373-386.
[30]Law C K,Jomaas G,Bechtold J K.Cellular instabilities of expanding hydrogen/propane spherical flames at elevated pressures:theory and experiment[J].Proceedings of the Combustion Institute,2005,30(1):159-167.
[31]Wu F,Jomaas G,Law C K.An experimental investigation on self-acceleration of cellular spherical flames[J].Proceedings of the Combustion Institute,2013,34(1):937-945.
[32]王保国,刘淑艳,黄伟光.气体动力学[M].北京:北京理工大学出版社,2005.
[33]Livengood J C,Wu P C.Correlation of autoignition phenomena in internal combustion engines and rapid compression machines[C]//Symposium(International)on combustion.Elsevier,1955,5(1):347-356.
[34]Winklhofer E,Hirsch A,Kapus P,et al.TC GDI engines at very high power density—irregular combustion and thermal risk[R].SAE Technical Paper,2009.
[35]Kalghatgi G T,Bradley D,Andrae J,et al.The nature of‘superknock’and its origins in SI engines[C]//Proc Conf on Internal Combustion Engines:Performance,Fuel Economy and Emissions,London,UK,2009.
[36]Yu H,Chen Z.End-gas autoignition and detonation development in a closed chamber[J].Combustion and Flame,2015,162(11):4102-4111.
[37]Wei H,Gao D,Zhou L,et al.Different combustion modes caused by flame-shock interactions in a confined chamber with a perforated plate[J].Combustion and Flame,2017,178:277-285.
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