碳氢燃料超声速燃烧室火焰稳定机制研究
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摘要
在来流总温1085K、进口马赫数2.0下开展了煤油燃料超声速燃烧试验,使用高速摄像观测了火焰的形态和结构,采用平面激光诱导荧光技术(PLIF)观测了煤油和OH的分布,结合数值模拟结果分析了燃烧室的火焰稳定机制。测量结果显示:燃烧反应主要发生在射流的下游区域和凹槽区域内,随着燃料当量比的增加,火焰传播角度及火焰向主流的穿透高度增加。数值模拟结果与实验测量吻合较好。火焰稳定机制分析显示:液态煤油喷入燃烧室内,主要分布在下壁面附近的流场中,燃烧产生的高温燃烧产物通过凹槽剪切层与回流区之间的相互作用,进入凹槽并为剪切层中的空气-煤油混合气体提供稳定的热量和中间产物,使得火焰基底能够稳定在剪切层内,并以相对固定的角度向主流流场中传播。
Supersonic kerosene combustion experiments were conducted at stagnation temperature of 1085 Kand inlet Mach number of 2.0.High speed camera was applied to observe the shape and structure of the flame.PLIF was used to observe the distributions of kerosene and OH.Flame stabilization mechanism was analyzed with the combination of numerical and experimental results.The experimental results show that the combustion reaction occurs in the downstream of the jet stream and in the cavity region.The spread angle and the penetration height of the flame are increased with the increase of the equivalence ratio.Numerical simulations show a reasonable agreement with the experimental results.The flame stabilization mechanism analysis indicates that the kerosene fuel is mostly distributed in the region near the floor after injected into the combustor in the liquid state.Combustion product with high temperature was transported into the cavity through the interaction between the cavity shear layer and the circulation.This process provides heat and radicals to the mixture of air-kerosene in the shear layer.Hence,the flame base is able to be stabilized in the shear layer and spread to the mainstream at a constant angle.
Supersonic kerosene combustion experiments were conducted at stagnation temperature of 1085 Kand inlet Mach number of 2.0.High speed camera was applied to observe the shape and structure of the flame.PLIF was used to observe the distributions of kerosene and OH.Flame stabilization mechanism was analyzed with the combination of numerical and experimental results.The experimental results show that the combustion reaction occurs in the downstream of the jet stream and in the cavity region.The spread angle and the penetration height of the flame are increased with the increase of the equivalence ratio.Numerical simulations show a reasonable agreement with the experimental results.The flame stabilization mechanism analysis indicates that the kerosene fuel is mostly distributed in the region near the floor after injected into the combustor in the liquid state.Combustion product with high temperature was transported into the cavity through the interaction between the cavity shear layer and the circulation.This process provides heat and radicals to the mixture of air-kerosene in the shear layer.Hence,the flame base is able to be stabilized in the shear layer and spread to the mainstream at a constant angle.
引文
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[2] Barnes F W,Segal C.Cavity-based flameholding for chemicallyreacting supersonic flows[J].Progress in Aerospace Sciences,2015,76:24-41.
[3] Li X P,Liu W D,Pan Y,et al.Characterization of kerosene distribution around the ignition cavity in a scramjet combustor[J].Acta Astronautica,2017,134:11-16.
[4] Li X P,Liu W D,Yang L C,et al.Experimental investigation on fuel distribution in a scramjet combustor with dual cavity[J].Journal of Propulsion and Power,2017,34(2):1-5.
[5] Fotia M L.Experimental study of shock-train/combustion coupling and flame dynamics in a heated supersonic flow[D].The University of Michigan,2012.
[6] Micka D J.Combustion stabilization,structure,and spreading in a laboratory dual-mode scramjet combustor[D].The University of Michigan,2010.
[7] Micka D J,Torrez S M,Driscoll J F.Heat release distribution in a dual-mode scramjet combustor-measurements and modeling[R].AIAA 2009-7362,2009.
[8] Micka D J,Driscoll J F.Combustion characteristics of a dualmode scramjet combustor with cavity flameholder[J].Proceedings of the Combustion Institute,2009,32(2):2397-2404.
[9] Wang H B,Wang Z G,Sun M B,et al.Combustion modes of hydrogen jet combustion in a cavity-based supersonic combustor[J].International Journal of Hydrogen Energy,2013,38(27):12078-12089.
[10]Le J L,Yang S H,Li H B,et al.Analysis and correlation of flame stability limits in supersonic flow with cavity flameholder[R].AIAA 2012-5948,2012.
[11]Yuan Y M,Zhang T C,Yao W,et al.Study on flame stabilization in a dual-mode combustor using optical measurements[J].Journal of Propulsion and Power,2015,31(6):1524-1531.
[12]Kundu K P,Penko P F,Yang S L.Reduced reaction mechanisms for numerical calculations in combustion of hydrocarbon fuels[R].AIAA 98-0803,1998.
[13]Ben-Yakar A,Hanson R K.Cavity flame-holders for ignition and flame stabilization in scramjets:an overview[J].Journal of Propulsion and Power,2001,17(4):869-877.