摘要
燃气轮机燃烧室的点火是启动过程中的一个重要环节。通过它,可以向燃烧室输入一定能量,直接把主燃料炬点燃;或者使少量的启动燃料首先点着,形成点火火炬,然后依靠它再去点燃整个燃烧室的主燃料炬。当燃烧室的主火焰能够连续而又稳定地维持后,点火过程就此结束。
等离子体点火器是等离子体技术在动力与能源工程领域中应用而产生的一种新型点火装置。其高密度能量对空气或可燃混合物进行热学作用,进入等离子体点火器内的空气和雾状燃料经历的过程非常复杂,它涉及气体湍流流动、传热、传质、化学反应、辐射等过程。对描述其过程的非线性控制微分方程组,到目前还无法用解析法解出。对于燃烧设备来说,如果不能深刻理解和准确描述其工作过程,就很难将其变成更有效的工作装置。
本文对等离子体点火器内燃烧过程进行了三维模拟,通过构造反映等离子体点火器内部流动规律的基本方程组,建立了描述点火器内部复杂燃烧过程的数学模型。其模型包括:模拟湍流流动的标准的κ-ε模型;模拟内部湍流燃烧的非预混湍流燃烧模型;模拟辐射传热的DO辐射模型等。对于控制方程采用混合差分格式进行离散,壁面处理采用壁面函数法,压力速度耦合问题采用SIMPLE算法。
通过数值模拟计算,讨论了改变空气过量系数对等离子点火器出口面上燃气混合物组分、内能、化学能、出口点火能量的影响。并对燃烧组分发生变化时对等离子点火器出口面处上述各参数的影响做了分析。这对实际等离子体点火器的结构设计和改进将起到重要的指导意义。
The ignition of the combustor is the important problem during the startup of the gas turbine. by it, can import the energy to the combustor, ignites host fuel torch directly; Or make a little fuel be burning first, forming firing torch, and then depend on it, ignites the host fuel torch of the combustor. When the host flame of the combustor could maintain stably, firing process is over at this point.
The plasma ignition is one of the new ignition device that produced when the plasma technology applied in the power and energy project domain. High density energy of the plasma ignition carries on the heat and chemical effect to the air and the fuel mixture, produced a great deal plasma activation carrier. The air and fog fuel experienced extremely complex process, which involves the turbulence folw, heat transfer, chemical reaction, radiation and so on. For the non-linear controls simultaneous differential equation that descript the process we can not solve it with the analysis law. As for the burning equipment if we can not profoundly understand and accurately descripe its work process, that will difficult to construct effective equipment.
This article has carried on the three dimensional simulation to the combustion process that in the plasma ignition, constituting some the equations which reflect the flow law and building many mathematical models of physical and chemical reactions in the plasma ignition: applying k -εturbulence model to calculate the turbulence parameters; applying the non-premixed combustion model to simulate the turbulence combustion; applying the DO model to simulate the radiation heat transfer. Using the mixing format to disperse the equations and applying SIMPLE algorithm method to solve pressure-velocity coupling.
Through the numerical simulation, discussed impact on the parameters by changed the air coefficient, these parameters include the composition of the combustion, internal energy, chemical energy and the total energy in the outlet of the plasma ignition by changed the air coefficient Analysed the impact on the parameters that have mentioned above in the outlet of the plasma ignition through changed the combustion composition. These results are significant to design and improve the plasma ignition.
引文
[1] J R罗思.工业等离子体工程.第一卷.吴建强等译.北京:科学出版社,1998
[2] 胡征.等离子体化学基础.化工时刊.1999(11):39-41页
[3] 李静海等.展望21世纪的化学工程.北京:化学工业出版社,2004
[4] Polack L, etal. Plasma Chemistry. London:Chambridge International Scientific Publishing, 1998
[5] 过增元,赵文华.电弧和热等离子体.北京:科学出版社,1986
[6] TJM博伊德等.等离子体动力学.戴世强等译.北京:科学出版社,1977
[7] Fridman A, Chirokov A and Gutsol A. Non-thermal atmospheric pressure discharge,J. Phys. D: Appl. Phys.38(2005) R1-R24
[8] 马腾才等.等离子体物理原理.合肥:中国科学技术大学出版社,1988
[10] 靳宝林,郑永成.航空发动机等离子流点火技术探讨.航空发动机.2002(4):51-55页
[11] 王学年,施侠等.等离子点火技术的应用研究.华东电力.2003(10):24-26页
[12] 赵仕厂.发动机点火器燃烧流场的数值模拟.哈尔滨工程大学硕士学位论文.2004:4-11页
[13] 包吉威.等离子点火器燃烧流场的数值模拟.哈尔滨工程大学硕士学位论文.2002:2-9页
[14] 李志华.等离子体点火器湍流扩散燃烧数值模拟分析.哈尔滨工程大学博士学位论文.2006:3-10页
[15] 严传俊,范玮等.燃烧学.西北工业大学出版社,2005
[16] FLUENT,http://www.fluent.com
[17] Irvin Glassman. Combustion. Academic Press. Inc. New York, 1977
[18] Kuo K.K. Principle of Combustion John Wiley Sons, New York,1986
[19] Spalding D. B. Mixing and chemical reaction in steady confined turbulent flames. 13.Symp. (Int.)on Combust.1971
[20] Pope S. B.PDF methods for turbulent reactive flows. Prog Energy Combust.Sci.,(1985) 11:119P
[21] Bilger,R.VP.Conditional moment closure for turbulent reacting flow. Physics of Fluids A:Feb93,Vol.436P.9P
[22] Klimenko, A. Yu. Note on the conditional moment closure in turbulent shear flows Physics of Fluids Feb95,Vol.446P
[23] Illiams, F. A. Turbulent Mixing in Non-Reactive Flows. S. N. B. Murthy, Ed.,1975:189P
[24] Peters N. Laminar Diffusion Flamelet Models in Non-Premixed Turbulent Combustion .Progress in Energy and Combustion Science,(1984)10:319-339P
[25] Peters, N. Laminar Flamelet Concepts In Turbulent Combustion: Progress in Energy and Combustion Science 10,1984:319-339P
[26] WestBrook C K., Dryer F L. Chemical Kinetic Modeling of Hydrocarbon Combustion. Progress in Energy and Combustion Science,(1984)10:1-57P
[27] 岑可法,樊建人.燃烧流体力学.北京:水利电力出版社,1991
[28] Hautman D J, Dryer F L,Schug K P, Glassman I.A Multiple-Step Overall Kinetic Mechanism for the Oxidation of Hydrocarbons,Combustion Science and Technology,(1981)27:31-43P
[29] Kanffman F, Ckemical Kinetics and Combustion.Intricate Path and Simple Step.Nineteenth Symposium (International) on Combustion, The Combustion Institute, Pitsburg PA, 1982:1-10P
[30] W.P.Jones and J.H.Whitelaw, Combust.Flame.48,1(1982)
[31] 郑洪涛,等.等离子发生器中流场的组织与电极冷却.哈尔滨工程大学学报,2002,23(4):33~38页
[32] 陶文铨著.计算传热学的近代发展.北京:科学出版社,2000.64-79页
[33] S.V.帕坦卡著.张政译.传热与流体流动的数值计算.北京:科学出版社,1992:68-70页
[34] S.V.Patanker, D.B.Spalding, A calculation processure for heat, mass and momentum transfer in three-dimensional parabolic flows. Int J Heat Mass Transfer,(1972)15:1787-1806P
[35] H.K.Versteeg,W.Malasekera, An Introduction to Computational Fluid Dynamics:The Finite Volume Method. Wiley,New York, 1995
[36] 周校平,张晓男.燃烧理论基础.上海:上海交通大学,2001:2-5页
[37] 赵新生.化学反应理论导论.北京:北京大学出版社,2003:22-91页
[38] 欧文.燃烧学.北京:科学出版社,1983:8-59页
[39] 曾宪诚,张元勤.化学反应热动力学理论与方法.北京:化学工业出版社,2003:3-101页
[40] 周鲁,刘钟海.复杂反应动力学基础.成都:成都科技大学出版社.1994:12-110页