基于分形几何的超声速燃烧火焰形态表征方法研究
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摘要
分形几何是图像学发展的新兴学科。通过分形几何,可以研究不规则图形,揭示图形的自相似特性,并且给出图形自相似性的定量数据。本文将分形几何用于分析超声速气流中的火焰形态,定量分析了不同当量比与燃料组分摩尔比条件下火焰分形维数的变化规律,研究了湍流火焰传播速度和火焰边界分形维数之间的对应关系。通过高速摄影获得的火焰CH*自发光瞬态图像,记录了马赫数2.5超声速气流中不同燃料的火焰形态,验证了超声速火焰边界具有自相似性。实验结果表明,超声速燃烧湍流火焰锋面边界的分形维数随当量比的增大近似线性增大,随着燃料中氢含量的增加而增大。
Fractal geometry is a new subject of graphics.By means of fractal geometry,irregular graphics can be studied,the self-similarity characteristics of graphs can be revealed,and quantitative data of graph self-similarity can be given.In this paper,the fractal geometry is used to analyze the flame morphology in the supersonic airflow,and the variation law of the flame fractal dimension under the condition of different equivalent ratios and fuel component molar ratios is quantitatively analyzed.The relationship between the velocity of the turbulent flame propagation and the fractal dimension of the flame boundary is studied.In this paper,the flame CH*self-luminescent transient image obtained by the high-speed photography is used to record the flame morphology of different fuels in the Mach number 2.5 supersonic airflow.The experimental results show that the fractal dimension of the frontal boundary of the supersonic combustion turbulent flame increases approximately linearly with the increase of the equivalent ratio,and increases with the increase of the hydrogen component in the fuel.
Fractal geometry is a new subject of graphics.By means of fractal geometry,irregular graphics can be studied,the self-similarity characteristics of graphs can be revealed,and quantitative data of graph self-similarity can be given.In this paper,the fractal geometry is used to analyze the flame morphology in the supersonic airflow,and the variation law of the flame fractal dimension under the condition of different equivalent ratios and fuel component molar ratios is quantitatively analyzed.The relationship between the velocity of the turbulent flame propagation and the fractal dimension of the flame boundary is studied.In this paper,the flame CH*self-luminescent transient image obtained by the high-speed photography is used to record the flame morphology of different fuels in the Mach number 2.5 supersonic airflow.The experimental results show that the fractal dimension of the frontal boundary of the supersonic combustion turbulent flame increases approximately linearly with the increase of the equivalent ratio,and increases with the increase of the hydrogen component in the fuel.
引文
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[9]程柳维,仲峰泉,王知溥,等.超声速燃烧室乙烯/氢混合燃料点火及火焰形态的实验研究[C].第九届全国高超声速科技学术会议,西安,2016.Cheng L W,Zhong F Q,Wang Z P,et al.Experimental study of ignition and flame shape of blended fuel of ethylene/hydrogen in a supersonic combustor[C]//Proc of the 9th National Conference on Hypersonic Science and Technology.2016.
[10]王玲玲,金忠青.分形理论及其在紊流研究中的应用[J].河海大学学报,1997,25(1):1-5.Wang L L,Jin Z Q.Fractal theory and its application to turbulence study[J].Journal of Hohai University,1997,25(1):1-5.
[11]沈学会,陈举华.分形与混沌理论在湍流研究之中的应用[J].河南科技大学学报:自然科学版,2005,26(1):27-30.Shen X H,Chen J H.Application of fractal and chaos theory in turbulence study[J].Journal of Henan University of Science and Technology:Natural Science,2005,26(1):27-30.
[12]孟艳玲.汽油机燃烧火焰的分形特征研究[D].天津:天津大学,2007.Meng Y L.Study on fractal characteristics of combustion flame in gasoline engine[D].Tianjin:Tianjin University,2007.
[13]Fureby C.A fractal flame-wrinkling large eddy simulation model for premixed turbulent combustion[J].Proceedings of the Combustion Institute,2005,30(1):593-601.
[14]Cintosun E,Smallwood G L,Güldermer L.Flame surface fratcal characteristics in premixed turbulent combustionat high turbulence intensities[J].AIAA Journal,2007,45(11):2785-2789.
[15]Gouldin F C.An application of fractals to modeling premixed turbulent flames[J].Combustion and Flame,1987,68(3):249-266.
[16]Peters N.The turbulent burning velocity for large-scale and small-scale turbulence[J].Journal of Fluid Mechanics,1999,384:107-132.
[17]Cant R S,Mastorakos E.An introduction to turbulent reacting flows[M].UK:Imperical College Press,2007.
[2]Mandelbrot B B.The fractal geometry of nature[M].New York:Times Books,1982.
[3]Sreenivasan K R,Meneveau C.The fractal facets of turbulence[J].Journal of Fluid Mechanics,1986,173:357-386.
[4]赵玉新,易仕和,田立丰,等.超声速湍流混合层实验图像的分形度量[J].中国科学(G辑:物理学力学天文学),2008,38(5):562-571.Zhao Y X,Yi S H,Tian L F,et al.Fractal measurement of experimental images of supersonic turbulent mixing layer[J].Science in China(Series G:Physics,Mechanics&Astronomy),2008,38(5):562-571.
[5]杨宏旻,顾璠,刘勇,等.湍流预混火焰传播速度的分形模型研究[J].工程热物理学报,2001,22(4):507-510.Yang H M,Gu P,Liu Y,et al.The investigation on fractal model of the propagating speed of turbulent premixed flame[J].Journal of Engineering Thermophysics,2001,22(4):507-510.
[6]蒋德明,马凡华,杨迪.预混湍流火焰结构的分形特征[J].西安交通大学学报,1999,33(2):22-24.Jiang D M,Ma F H,Yang D.The fractal nature of turbulent premixed flame structure[J].Journal of Xi’an Jiaotong University,1999,33(2):22-24.
[7]Hiraoka K,Minamoto Y,Shimura M,et al.A fractal dynamic SGS combustion model for large eddy simulation of turbulent premixed flames[J].Combustion Sciences&Technology,2016,188(9):1472-1495.
[8]Cheng L W,Zhong F Q,Wang Z P,et al.Experimental study of ignition and flame characteristics of surrogate of cracked hydrocarbon fuels in supersonic crossflow[R].AIAA-2017-2295,2017.
[9]程柳维,仲峰泉,王知溥,等.超声速燃烧室乙烯/氢混合燃料点火及火焰形态的实验研究[C].第九届全国高超声速科技学术会议,西安,2016.Cheng L W,Zhong F Q,Wang Z P,et al.Experimental study of ignition and flame shape of blended fuel of ethylene/hydrogen in a supersonic combustor[C]//Proc of the 9th National Conference on Hypersonic Science and Technology.2016.
[10]王玲玲,金忠青.分形理论及其在紊流研究中的应用[J].河海大学学报,1997,25(1):1-5.Wang L L,Jin Z Q.Fractal theory and its application to turbulence study[J].Journal of Hohai University,1997,25(1):1-5.
[11]沈学会,陈举华.分形与混沌理论在湍流研究之中的应用[J].河南科技大学学报:自然科学版,2005,26(1):27-30.Shen X H,Chen J H.Application of fractal and chaos theory in turbulence study[J].Journal of Henan University of Science and Technology:Natural Science,2005,26(1):27-30.
[12]孟艳玲.汽油机燃烧火焰的分形特征研究[D].天津:天津大学,2007.Meng Y L.Study on fractal characteristics of combustion flame in gasoline engine[D].Tianjin:Tianjin University,2007.
[13]Fureby C.A fractal flame-wrinkling large eddy simulation model for premixed turbulent combustion[J].Proceedings of the Combustion Institute,2005,30(1):593-601.
[14]Cintosun E,Smallwood G L,Güldermer L.Flame surface fratcal characteristics in premixed turbulent combustionat high turbulence intensities[J].AIAA Journal,2007,45(11):2785-2789.
[15]Gouldin F C.An application of fractals to modeling premixed turbulent flames[J].Combustion and Flame,1987,68(3):249-266.
[16]Peters N.The turbulent burning velocity for large-scale and small-scale turbulence[J].Journal of Fluid Mechanics,1999,384:107-132.
[17]Cant R S,Mastorakos E.An introduction to turbulent reacting flows[M].UK:Imperical College Press,2007.
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