高压环境下二甲基醚射流破碎模拟研究
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摘要
二甲基醚是压燃式发动机的优质替代燃料。对于压燃式发动机其燃料喷射质量是影响混合气形成的决定性因素,喷雾破碎雾化质量的优劣直接影响到内燃机的燃烧性能,并进而决定了发动机的动力性、经济性及排放特性。因此,对二甲基醚喷射过程以及喷雾特性进行深入的研究将有助于深入了解二甲基醚燃烧机理,对优化二甲基醚发动机喷射系统和燃烧系统的参数,改善发动机燃用二甲基醚的性能有重要的理论意义和使用价值。
本文在综合分析目前有关发动机燃油喷雾雾化机理和喷雾过程研究成果的基础上,应用连续液滴的处理方法,采用k-ε两方程湍流模型,建立了基于VOF多相流跟踪方式的喷雾破碎过程的数值模拟方法。经与试验结果比较,表明模拟结果吻合较好,验证了所建立模型的准确性。
本文在前人对二甲基醚热物性参数试验和理论研究的基础上,编制二甲基醚的物性参数接口程序,对二甲基醚喷雾破碎过程开展了变参数分析研究,结果表明:增大环境背压、喷孔直径和启喷压力有利于提高喷雾的破碎质量。
利用混合多相流体模型加空穴模型的方法,对圆柱喷孔内稳态二甲基醚流动进行了数值模拟。探讨了空穴产生的原因及对二甲基醚射流破碎的作用,研究表明喷孔内存在的低于二甲基醚饱和蒸汽压的压力是空穴产生的原因;湍流扰动、空气动力作用和空穴流动是引起二甲基醚高速射流破碎的主要原因。
DME (dimethyl ether) is a high-quality alternative fuel for compression-ignition engine. Injection quality of the fuel is the critical factor of the formation of the gas mixture for compression-ignition engine, which influences the combustion performance of combustion engine, and determine the power and the economy of the engine. Therefore, the deep research of DME spray characteristics are helpful for understanding the combustion of DME, which has a important theoretical significance and useful value for optimizing the injection and combustion system of DME engine.
Based on the comprehensive analysis of the mechanism and process of the engine fuel sprays, The characteristics of DME jet breakup are simulated, which are adopted by the CDM mode, the k-εdouble equation model and the VOF track method, the simulation results are in accord with the tests by comparison, and the spray modes are proved correct.
The program of DME physicochemical parameter is established based on the predecessor’s research of DME physicochemical characteristics. The variable parameter process of the DME injection is investigated. The simulation results show that the better quality of the jet breakup can be realized by increasing the ambient pressure, nozzle hole diameter and inject pressure.
The cavitation flow of the DME in a nozzle is numerical simulated using mixed multiphase flow model coupled with cavitation model. The reasons of the cavitation generation and the effects on the DME breakup are studied, the pressure in the spray hole which is below the saturated vapor pressure of the DME result in the cavitation generation, the main causes which influence on the DME breakup of the high speed are the turbulence interference, the air-power compact and the cavitation flow.
本文在综合分析目前有关发动机燃油喷雾雾化机理和喷雾过程研究成果的基础上,应用连续液滴的处理方法,采用k-ε两方程湍流模型,建立了基于VOF多相流跟踪方式的喷雾破碎过程的数值模拟方法。经与试验结果比较,表明模拟结果吻合较好,验证了所建立模型的准确性。
本文在前人对二甲基醚热物性参数试验和理论研究的基础上,编制二甲基醚的物性参数接口程序,对二甲基醚喷雾破碎过程开展了变参数分析研究,结果表明:增大环境背压、喷孔直径和启喷压力有利于提高喷雾的破碎质量。
利用混合多相流体模型加空穴模型的方法,对圆柱喷孔内稳态二甲基醚流动进行了数值模拟。探讨了空穴产生的原因及对二甲基醚射流破碎的作用,研究表明喷孔内存在的低于二甲基醚饱和蒸汽压的压力是空穴产生的原因;湍流扰动、空气动力作用和空穴流动是引起二甲基醚高速射流破碎的主要原因。
DME (dimethyl ether) is a high-quality alternative fuel for compression-ignition engine. Injection quality of the fuel is the critical factor of the formation of the gas mixture for compression-ignition engine, which influences the combustion performance of combustion engine, and determine the power and the economy of the engine. Therefore, the deep research of DME spray characteristics are helpful for understanding the combustion of DME, which has a important theoretical significance and useful value for optimizing the injection and combustion system of DME engine.
Based on the comprehensive analysis of the mechanism and process of the engine fuel sprays, The characteristics of DME jet breakup are simulated, which are adopted by the CDM mode, the k-εdouble equation model and the VOF track method, the simulation results are in accord with the tests by comparison, and the spray modes are proved correct.
The program of DME physicochemical parameter is established based on the predecessor’s research of DME physicochemical characteristics. The variable parameter process of the DME injection is investigated. The simulation results show that the better quality of the jet breakup can be realized by increasing the ambient pressure, nozzle hole diameter and inject pressure.
The cavitation flow of the DME in a nozzle is numerical simulated using mixed multiphase flow model coupled with cavitation model. The reasons of the cavitation generation and the effects on the DME breakup are studied, the pressure in the spray hole which is below the saturated vapor pressure of the DME result in the cavitation generation, the main causes which influence on the DME breakup of the high speed are the turbulence interference, the air-power compact and the cavitation flow.
引文
[1]刘永长.内燃机原理.武汉:华中科技大学出版社, 2001
[2]张煜盛,常汉保.柴油机高效清洁燃料二甲基醚(DME)的研究及其发展.内燃机工程, 2001(3)
[3] Yoshio Sato, Shinya Nozaki,Toshifumi Noda. The Performance of a Diesel Engine for Light Duty Truck Using a Jerk Type In-Line DME injection System. SAE Paper 982537, 1989
[4]魏文德.有机化工原料大全.第二卷.北京:化学工业出版社, 1989: 177
[5] V.I.Golovitchev et al.Neat Dimethyl Ether: Is It Really Diesel Fuel of Promise. SAE Paper 982537, 1998
[6] H.Ofner and D.W.Gill. Dimethyl Ether as Fuel for CI Engines-A New Technology and its Environmental Potential. SAE Paper 981158
[7] MCCANDLESS James C. Development of a Novel Fuel Injection System(NFIDS)for Dimethyl Ether and Other Clean Alternative Fuel[C]: SAE Paper 970220, 1997
[8] SORENSON SpencerC. Dimethyl Ether in Diesel Fuel Injection Systems[C]:SAE Paper 981159, 1998
[9]解茂昭.内燃机计算燃烧学.大连:大连理工大学出版社, 1996
[10] Roache. P J. Computational Fluid Dynamics. Hermosa Publishers, 1976
[11] Patankar S V. Numerical Heat Transfer and Fluid Flow. McGraw-Hill, 1980
[12] Faeth G M. Mixing, Transport and Combustion in Sprays. Prog. Energy Combust Sci., Vol.13, pp. 293~345, 1987
[13] Hsiang L P, Faeth G M. Drop Properties after Secondary Breakup. Int. J. Multiphase Flow,Vol.19, No. 5, pp. 721~735, 1993
[14] Faeth G M, Hsiang L P, Wu P K. Structure and Breakup Properties of Sprays. Int. J. Multi-phase Flow, Vol.21, Suppl, pp. 99~127, 1995
[15] Reitz, R.D. Breakup regimes of a single liquid jet. American Mathematical Society, 1976
[16] Ranz,W.E. Some experiments on orifice sprays. Can. J. Chem. Eng., 1958,Vol.36: 175-181
[17] Reitz, R.D., Bracco, F.V. Mechanism of atomization of a liquid jet. Phys. Fluids, 1982, Vol.25: 1730-1742
[18] Reitz, R.D., Bracco, F.V. Mechanism of atomization of a liquid jet. The Encyclopedia of Fluid Mechanics,ed. N. Cheremisnoff. Vol.3, 233-249. 1986
[19] Lin, S.P., Kang, D.J.Atomization of a liquid jet. Phys. Fluids, 1987,Vol.30: 2000-2006
[20] Lin, S.P., Lian, Z.W. Mechanism of atomization.AIAAJ., 1990, Vol.28: 120-126
[21] Liu, A.B., Mather, D., Reitz, R.D. Modeling the effects of drop drag and breakup on fuel sprays. SAE Paper 930072, 1993.
[22] Yang, H.Q. Asymmetric instability of a liquid jet. Phys. Fluids, 1992, Vol.A4: 681-689
[23] Li, X. Mechanism of atomization of a liquid jet. Atomization and Spray, 1995, Vol.5: 89-105
[24]易世君,解茂昭,陈白欣.粘性液体射流分裂与雾化机理.力学学报(英文版), 1996
[25]宋军.内燃机燃油雾化与喷雾两相流的多维模拟研究[博士学位论文].华中理工大学, 1996
[26]史绍熙,郗大光,秦建荣.液体射流的非轴对称破碎.燃烧科学与技术, 1996, Vol.2(3): 189-199
[27]史绍熙,郗大光,秦建荣.高速粘性液体射流的不稳定模式.内燃机学报, 1997, Vol.15(1): 1-7
[28]史绍熙,郗大光,刘宁.液体燃料射流破碎机理研究中的时间模式与空间模式.内燃机学报, 1999, Vol.17(3): 205-210
[29]杜青,史绍熙,刘宁.液体燃料射流最不稳定频率的理论分析.内燃机学报, 2000, Vol.18(3):283-287
[30]徐海涛.直喷式柴油机喷雾混合机理、建模及三维数值模拟[博士学位论文].华中理工大学, 1998
[31] Yuen, M.C. Non-linear capillary instability of a liquid jet. J. Fluid Mech., 1968, Vol.33(1): 151-163
[32] Dejuhasz, K.J. Dispersion of sprays in solid-injection oil engines. Trans. ASME, 1933, Vol.53:65-67
[33] Rupe J H. Jet Propulsion Laboratory Technical Report No.32, 207, 1972
[34] Shkador V Ya. Fluid Dyn. Vol.5, 473, 1970
[35] Bergwerk W. Proc. Inst. Mech. Eng. Vol.173, 655, 1959
[36] Chaves H, Knapp M. Experimental Study of Cavitation in the Nozzle Hole of Diesel Injector Using Transparent Nozzles [C]. SAE paper 950290, 1995
[37] Roosen P, Unruh O, Behmann M. Untersuchung und Modellierung des Transientens von Kavitationser-scheinungen bei ein-und Mechkomponentigen Kraftsoffen in Schnell Durchstromten Dusen[C]. Report of the Institute for Technical Thermodynamics, RWTH Aachen, Germany, 1996
[38]张煜盛.直喷式柴油机油-气混合过程的数学模型研究[博士学位论文].华中工学院, 1987
[39]王应时,范维澄,周力行,徐旭常.燃烧过程数值计算.科学出版社, 1986
[40]范维澄,万跃鹏流动及燃烧的模型与计算.中国科学技术大学出版社, 1992
[41]周雪漪.计算水力学.北京:清华大学出版社, 1995
[42]陶文铨.数值传热学(第二版).西安:西安交通大学出版社, 2001
[43]郭鸿志.传输过程数值模拟.北京:冶金工业出版社, 1998
[44] Anderson, John David. Computional fluid dynamics: the basics with applications. McGraw-Hill, Inc., 1995
[45] H.K. Versteeg, W. Malalasekera, An Introduction to Computional Fluid Dynamics: The Finite Volume Method. Wiley, New York, 1995
[46]黄克智,薛明德,陆明万.张量分析.北京:清华大学出版社, 2003
[47] Fluent Inc., FLUENT User’s Guide. Fluent Inc.,2003
[48] J.O Hinze, Turbulence. McGraw-Hill, New York, 1975
[49] Marzio Piller, Enrico Nobile, J. Thomas, DNS study of turbulent transport at low Prandtl numbers in a channel flow. Journal of Fluid Mechanics, (458): 419-441, 2002
[50] J.G. Wissink. DNS of separating low Reynolds number flow in a turbine cascade with incoming wakes. International Journal of Heat and Fluid Flow, 24(4): 626-635, 2003
[51] C.J. Chen, S.Y. Jaw. Fundamentals of Turbulence Modeling. Taylor&Francis, Washington, 1998
[52] T.H. Shih, W.W. Liou, A. Shabbir, Z. G. Yang, J. Zhu, A newκ-ξeddy viscosity model for high Reynolds number turbulent flows. Comput Fluids. 24(3): 227-238, 1995
[53]王福军.计算流体动力学分析-CFD软件原理与应用.清华大学出版社, 2004
[54]韩占忠,王敬,兰小平. FLUENT流体工程仿真计算实例与应用.北京理工大学出版社, 2004
[55] Yue si C.L, Yaws, Carl L. Matheson气体数据手册.北京:化学工业出版社化学与应用化学出版中心, 2003
[56]吴江涛.高精度流体热物性测试实验系统的研制及二甲醚热物理性质的研究[博士学位论文].西安交通大学, 2003
[57] C. Badock, R. Wirth, A. Fath, A. Leipertz. Investigation of cavitation in real size diesel injection nozzles. International Journal of Heat and Fluid Flow, 20: 538-544, 1999
[58] Rabbitt R D. Fundamentals of Reciprocating Engine Airflow, PartⅠ:Valve Discharge and Combustion Chamber Effects. SAE 840337, 1984
[59] Schmidt D P, Corradini M L. Analytical Prediction of the Exit Flow of Cavitating Orifices[J]. Atomization and Sprays, 7(6): 54~65, 1997
[60] Schmidt D P, Corradini M L, Rutland C J. A Two-dimensional Non-equilibrium Model of Flashing Nozzle Flow[C]. In3rd AS ME/JSME Joint Fluids Engineering conference, 1999
[61]玉木伸茂.喷油嘴喷孔空穴现象对液体喷束雾化的影响[J].国外内燃机车, 1998, 338(8): 23-29
[2]张煜盛,常汉保.柴油机高效清洁燃料二甲基醚(DME)的研究及其发展.内燃机工程, 2001(3)
[3] Yoshio Sato, Shinya Nozaki,Toshifumi Noda. The Performance of a Diesel Engine for Light Duty Truck Using a Jerk Type In-Line DME injection System. SAE Paper 982537, 1989
[4]魏文德.有机化工原料大全.第二卷.北京:化学工业出版社, 1989: 177
[5] V.I.Golovitchev et al.Neat Dimethyl Ether: Is It Really Diesel Fuel of Promise. SAE Paper 982537, 1998
[6] H.Ofner and D.W.Gill. Dimethyl Ether as Fuel for CI Engines-A New Technology and its Environmental Potential. SAE Paper 981158
[7] MCCANDLESS James C. Development of a Novel Fuel Injection System(NFIDS)for Dimethyl Ether and Other Clean Alternative Fuel[C]: SAE Paper 970220, 1997
[8] SORENSON SpencerC. Dimethyl Ether in Diesel Fuel Injection Systems[C]:SAE Paper 981159, 1998
[9]解茂昭.内燃机计算燃烧学.大连:大连理工大学出版社, 1996
[10] Roache. P J. Computational Fluid Dynamics. Hermosa Publishers, 1976
[11] Patankar S V. Numerical Heat Transfer and Fluid Flow. McGraw-Hill, 1980
[12] Faeth G M. Mixing, Transport and Combustion in Sprays. Prog. Energy Combust Sci., Vol.13, pp. 293~345, 1987
[13] Hsiang L P, Faeth G M. Drop Properties after Secondary Breakup. Int. J. Multiphase Flow,Vol.19, No. 5, pp. 721~735, 1993
[14] Faeth G M, Hsiang L P, Wu P K. Structure and Breakup Properties of Sprays. Int. J. Multi-phase Flow, Vol.21, Suppl, pp. 99~127, 1995
[15] Reitz, R.D. Breakup regimes of a single liquid jet. American Mathematical Society, 1976
[16] Ranz,W.E. Some experiments on orifice sprays. Can. J. Chem. Eng., 1958,Vol.36: 175-181
[17] Reitz, R.D., Bracco, F.V. Mechanism of atomization of a liquid jet. Phys. Fluids, 1982, Vol.25: 1730-1742
[18] Reitz, R.D., Bracco, F.V. Mechanism of atomization of a liquid jet. The Encyclopedia of Fluid Mechanics,ed. N. Cheremisnoff. Vol.3, 233-249. 1986
[19] Lin, S.P., Kang, D.J.Atomization of a liquid jet. Phys. Fluids, 1987,Vol.30: 2000-2006
[20] Lin, S.P., Lian, Z.W. Mechanism of atomization.AIAAJ., 1990, Vol.28: 120-126
[21] Liu, A.B., Mather, D., Reitz, R.D. Modeling the effects of drop drag and breakup on fuel sprays. SAE Paper 930072, 1993.
[22] Yang, H.Q. Asymmetric instability of a liquid jet. Phys. Fluids, 1992, Vol.A4: 681-689
[23] Li, X. Mechanism of atomization of a liquid jet. Atomization and Spray, 1995, Vol.5: 89-105
[24]易世君,解茂昭,陈白欣.粘性液体射流分裂与雾化机理.力学学报(英文版), 1996
[25]宋军.内燃机燃油雾化与喷雾两相流的多维模拟研究[博士学位论文].华中理工大学, 1996
[26]史绍熙,郗大光,秦建荣.液体射流的非轴对称破碎.燃烧科学与技术, 1996, Vol.2(3): 189-199
[27]史绍熙,郗大光,秦建荣.高速粘性液体射流的不稳定模式.内燃机学报, 1997, Vol.15(1): 1-7
[28]史绍熙,郗大光,刘宁.液体燃料射流破碎机理研究中的时间模式与空间模式.内燃机学报, 1999, Vol.17(3): 205-210
[29]杜青,史绍熙,刘宁.液体燃料射流最不稳定频率的理论分析.内燃机学报, 2000, Vol.18(3):283-287
[30]徐海涛.直喷式柴油机喷雾混合机理、建模及三维数值模拟[博士学位论文].华中理工大学, 1998
[31] Yuen, M.C. Non-linear capillary instability of a liquid jet. J. Fluid Mech., 1968, Vol.33(1): 151-163
[32] Dejuhasz, K.J. Dispersion of sprays in solid-injection oil engines. Trans. ASME, 1933, Vol.53:65-67
[33] Rupe J H. Jet Propulsion Laboratory Technical Report No.32, 207, 1972
[34] Shkador V Ya. Fluid Dyn. Vol.5, 473, 1970
[35] Bergwerk W. Proc. Inst. Mech. Eng. Vol.173, 655, 1959
[36] Chaves H, Knapp M. Experimental Study of Cavitation in the Nozzle Hole of Diesel Injector Using Transparent Nozzles [C]. SAE paper 950290, 1995
[37] Roosen P, Unruh O, Behmann M. Untersuchung und Modellierung des Transientens von Kavitationser-scheinungen bei ein-und Mechkomponentigen Kraftsoffen in Schnell Durchstromten Dusen[C]. Report of the Institute for Technical Thermodynamics, RWTH Aachen, Germany, 1996
[38]张煜盛.直喷式柴油机油-气混合过程的数学模型研究[博士学位论文].华中工学院, 1987
[39]王应时,范维澄,周力行,徐旭常.燃烧过程数值计算.科学出版社, 1986
[40]范维澄,万跃鹏流动及燃烧的模型与计算.中国科学技术大学出版社, 1992
[41]周雪漪.计算水力学.北京:清华大学出版社, 1995
[42]陶文铨.数值传热学(第二版).西安:西安交通大学出版社, 2001
[43]郭鸿志.传输过程数值模拟.北京:冶金工业出版社, 1998
[44] Anderson, John David. Computional fluid dynamics: the basics with applications. McGraw-Hill, Inc., 1995
[45] H.K. Versteeg, W. Malalasekera, An Introduction to Computional Fluid Dynamics: The Finite Volume Method. Wiley, New York, 1995
[46]黄克智,薛明德,陆明万.张量分析.北京:清华大学出版社, 2003
[47] Fluent Inc., FLUENT User’s Guide. Fluent Inc.,2003
[48] J.O Hinze, Turbulence. McGraw-Hill, New York, 1975
[49] Marzio Piller, Enrico Nobile, J. Thomas, DNS study of turbulent transport at low Prandtl numbers in a channel flow. Journal of Fluid Mechanics, (458): 419-441, 2002
[50] J.G. Wissink. DNS of separating low Reynolds number flow in a turbine cascade with incoming wakes. International Journal of Heat and Fluid Flow, 24(4): 626-635, 2003
[51] C.J. Chen, S.Y. Jaw. Fundamentals of Turbulence Modeling. Taylor&Francis, Washington, 1998
[52] T.H. Shih, W.W. Liou, A. Shabbir, Z. G. Yang, J. Zhu, A newκ-ξeddy viscosity model for high Reynolds number turbulent flows. Comput Fluids. 24(3): 227-238, 1995
[53]王福军.计算流体动力学分析-CFD软件原理与应用.清华大学出版社, 2004
[54]韩占忠,王敬,兰小平. FLUENT流体工程仿真计算实例与应用.北京理工大学出版社, 2004
[55] Yue si C.L, Yaws, Carl L. Matheson气体数据手册.北京:化学工业出版社化学与应用化学出版中心, 2003
[56]吴江涛.高精度流体热物性测试实验系统的研制及二甲醚热物理性质的研究[博士学位论文].西安交通大学, 2003
[57] C. Badock, R. Wirth, A. Fath, A. Leipertz. Investigation of cavitation in real size diesel injection nozzles. International Journal of Heat and Fluid Flow, 20: 538-544, 1999
[58] Rabbitt R D. Fundamentals of Reciprocating Engine Airflow, PartⅠ:Valve Discharge and Combustion Chamber Effects. SAE 840337, 1984
[59] Schmidt D P, Corradini M L. Analytical Prediction of the Exit Flow of Cavitating Orifices[J]. Atomization and Sprays, 7(6): 54~65, 1997
[60] Schmidt D P, Corradini M L, Rutland C J. A Two-dimensional Non-equilibrium Model of Flashing Nozzle Flow[C]. In3rd AS ME/JSME Joint Fluids Engineering conference, 1999
[61]玉木伸茂.喷油嘴喷孔空穴现象对液体喷束雾化的影响[J].国外内燃机车, 1998, 338(8): 23-29