亚/超临界汽油多孔射流形态塌陷的研究
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摘要
基于GDI(gasolinedirectinjection)发动机常用工况点的缸内温度压力,采用高速摄影和纹影法,在高温环境下对比研究了亚/超临界汽油多孔和单孔及异辛烷多孔射流的宏观特性.结果表明:当燃油温度从亚临界态升高至超临界态时,汽油多孔射流在形态上表现出射流中心塌陷和前锋面凸起的特征,异于常见的枝状喷雾结构和剧烈闪沸条件下的坍缩喷雾,同时射流的贯穿距不断增加,锥角不断减小,射流宽度经历了先减小后增大的变化;亚临界汽油单孔射流的贯穿距、锥角及宽度的变化趋势异于汽油多孔射流,表明多孔射流相邻油束间的干涉重叠影响着射流形态结构,在汽油亚临界态时,干涉重叠导致射流轮廓向内收缩,使得射流锥角和宽度减小,而在汽油超临界态时,干涉重叠促进了多孔射流中心的塌陷;相比于单一组分的异辛烷,多组分物蒸发气化的沸点差异是导致汽油射流液相区发生剧烈闪急沸腾,使得射流轴线方向的低压核区发生气流卷吸,并最终诱发射流中心塌陷的原因,而塌陷的发生也使得燃油超临界态时汽油射流宽度大于异辛烷射流宽度;最后,通过对比亚/超临界汽油单孔射流和异辛烷多孔射流,发现导致亚/超临界汽油多孔射流前锋面凸起和中心塌陷的主要原因是射流相邻油束间的干涉重叠及轴线方向低压核区内的气流卷吸作用.
Based on the gasoline direct injection(GDI)engine common condition of temperature and pressure incylinder,the high-speed photography and schlieren method were used to compare the macro characteristics of the sub/supercritical states of gasoline multi-hole,single-hole,and isooctane multi-hole jets in high-temperature environments. The results demonstrate that when the fuel temperature rises from the subcritical state to the supercritical state,the center of the gasoline multi-hole jet collapses and shows a morphological protrusion of the front surface.This differs from the typical dendritic spray structure and collapse under severe flashing conditions,during which the penetration of the jet continuously increases,the cone angle continuously decreases,and the jet width first decreases and then increases. The development trends of the penetration,cone angle,and width of the sub-critical gasoline single-hole jets differ from those of the multi-hole jet,which indicates that the interference and overlap of the adjacent plumes affect the jet's morphological structure. With gasoline in the subcritical state,this interference and overlap cause the jet contour to shrink inward,thereby reducing its cone angle and width,while in the supercritical state of gasoline,the interference and overlap promote the collapse of the contour center of the multi-hole jet. Compared with one-component isooctane,the difference in the boiling point of multi-component vaporization and gasification leads to a sharp flash boiling in the liquid phase of the gasoline jet,causing airflow entrainment in the low-pressure nuclear region in the direction of the jet axis. This contributes to the eventual collapse of the jet center,which then leads to the gasoline jet width being larger than that of the isooctane jet when the fuel is in the supercritical state. Ultimately,the interference of the adjacent plumes and the airflow entrainment of the low-pressure nuclear region in the axial direction are the main reasons for the collapse of the multi-hole jet's center and the protrusion of the jet front faces of the sub-supercritical gasoline,by contrast with the sub/supercritical gasoline single-hole jet and the isooctane multi-hole jet.
Based on the gasoline direct injection(GDI)engine common condition of temperature and pressure incylinder,the high-speed photography and schlieren method were used to compare the macro characteristics of the sub/supercritical states of gasoline multi-hole,single-hole,and isooctane multi-hole jets in high-temperature environments. The results demonstrate that when the fuel temperature rises from the subcritical state to the supercritical state,the center of the gasoline multi-hole jet collapses and shows a morphological protrusion of the front surface.This differs from the typical dendritic spray structure and collapse under severe flashing conditions,during which the penetration of the jet continuously increases,the cone angle continuously decreases,and the jet width first decreases and then increases. The development trends of the penetration,cone angle,and width of the sub-critical gasoline single-hole jets differ from those of the multi-hole jet,which indicates that the interference and overlap of the adjacent plumes affect the jet's morphological structure. With gasoline in the subcritical state,this interference and overlap cause the jet contour to shrink inward,thereby reducing its cone angle and width,while in the supercritical state of gasoline,the interference and overlap promote the collapse of the contour center of the multi-hole jet. Compared with one-component isooctane,the difference in the boiling point of multi-component vaporization and gasification leads to a sharp flash boiling in the liquid phase of the gasoline jet,causing airflow entrainment in the low-pressure nuclear region in the direction of the jet axis. This contributes to the eventual collapse of the jet center,which then leads to the gasoline jet width being larger than that of the isooctane jet when the fuel is in the supercritical state. Ultimately,the interference of the adjacent plumes and the airflow entrainment of the low-pressure nuclear region in the axial direction are the main reasons for the collapse of the multi-hole jet's center and the protrusion of the jet front faces of the sub-supercritical gasoline,by contrast with the sub/supercritical gasoline single-hole jet and the isooctane multi-hole jet.
引文
[1]Zeng W,Xu M,Zhang G,et al.Atomization and vaporization for flash-boiling multi-hole sprays with alcohol fuels[J].Fuel,2012,95:287-297.
[2]段树林,冯林,宋永臣,等.闪急沸腾喷雾场粒度分布规律及燃烧特性的研究[J].内燃机学报,1999,17(1):54-58.Duan Shulin,Feng Lin,Song Yongchen,et al.Study on particle size distribution and combustion characteristics of flash boiling spray field[J].Transactions of CSICE,1999,17(1):54-58(in Chinese).
[3]Gele A,Hung D.Effect of nozzle configuration on macroscopic spray characteristics of multi-hole fuel injectors under superheated conditions[J].Atomization&Sprays,2016,26(5):439-462.
[4]Noyori T.Experimental study of smoke emission on small-displacement spark-ignition direct-injection engine[C]//SAE Technical Paper.Detroit,USA,2006:2006-32-0105.
[5]Dahms R N,Oefelein J C.Liquid jet breakup regimes at supercritical pressures[J].Combustion&Flame,2015,162(10):3648-3657.
[6]Boer C D,Chang J,Shetty S.Transonic combustionA novel injection-ignition system for improved gasoline engine efficiency[C]//SAE 2010 Powertrains Fuels&Lubricants Meeting.Detroit,USA,2010:559-561.
[7]Boer C D,Bonar G,Sasaki S,et al.Application of supercritical gasoline injection to a direct injection spark ignition engine for particulate reduction[C]//SAE Technical Paper.Detroit,USA,2013:2013-01-0257.
[8]Nishida K,Tian J,Sumoto Y,et al.An experimental and numerical study on sprays injected from two-hole nozzles for DISI engines[J].Fuel,2009,88:1634-1642.
[9]Nishida K,Gao J,Matsumoto Y.Experimental study on spray and mixture properties of the group-hole nozzle for direct-injection diesel engines,part II:Effects of included angle and interval between orifices[J].Atomization and Sprays,2009,19(4):339-355.
[10]Van Romunde Z,Aleiferis P G.Effect of operating conditions and fuel volatility on development and variability of sprays from gasoline direct-injection multi-hole injectors[J].Atomization and Sprays,2009,19(3):207-234.
[11]Aleiferis P G,van Romunde Z R.An analysis of spray development with iso-octane,n-pentane,gasoline,ethanol and n-butanol from a multi-hole injector under hot fuel conditions[J].Fuel,2012,105:143-168.
[12]Guo H,Ding H,Li Y,et al.Comparison of spray collapses at elevated ambient pressure and flash boiling conditions using multi-hole gasoline direct injector[J].Fuel,2017,199:125-134.
[13]邓鹏,黄荣华,马寅杰,等.强化混合条件下乙醇柴油和柴油的喷雾混合特性[J].内燃机学报,2014,32(2):144-151.Deng Peng,Huang Ronghua,Ma Yinjie,et al.Spray mixing characteristics of ethanol diesel and diesel under intensive mixing conditions[J].Transactions of CSICE,2014,32(2):144-151(in Chinese).
[14]裴毅强,王琨,张丹,等.GDI喷油器超高压乙醇喷雾的宏观特性[J].天津大学学报:自然科学与工程技术版,2018,51(7):755-762.Pei Yiqiang,Wang Kun,Zhang Dan,et al.Spray macroscopic characteristics of GDI injector fueled with ethanol using ultra-high injection pressure[J].Journal of Tianjin University:Science and Technology,2018,51(7):755-762(in Chinese).
[15]Hung D L S,Harrington D L,Gandhi A H,et al.Gasoline fuel injector spray measurement and characterization-A new SAE J2715 recommended practice[J].SAE International Journal of Fuels&Lubricants,2008,1(1):534-548.
[16]Lin Ronghong,Tavlarides L L.Thermophysical properties needed for the development of the supercritical diesel combustion technology:Evaluation of diesel fuel surrogate models[J].The Journal of Supercritical Fluids,2012,71:136-146.
[17]马沛生.石油化工基础数据手册[M].北京:化学工业出版社,1993.Ma Peisheng.Basic Data Handbook of Petrochemical Industry[M].Beijing:Chemical Industry Press,1993(in Chinese).
[18]张淼,裴毅强,郑朝蕾,等.亚临界/超临界汽油喷雾特性[J].内燃机学报,2015,33(5):420-425.Zhang Miao,Pei Yiqiang,Zheng Chaolei,et al.Characteristics of sub-supercritical gasoline spray[J].Transactions of CSICE,2015,33(5):420-425(in Chinese).
[19]解茂昭.内燃机跨临界/超临界燃料喷雾混合过程的机理与模型[J].燃烧科学与技术,2014,20(1):1-9.Xie Maozhao.Mechanism and model of crosscritical/supercritical fuel spray mixing process for internal combustion engines[J].Journal of Combustion Science and Technology,2014,20(1):1-9(in Chinese).
[20]姚卓,王天友,杨晟华,等.不同沸点燃料及其混合物的闪沸喷雾特性试验[J].内燃机学报,2014,32(4):316-321.Yao Zhuo,Wang Tianyou,Yang Chenghua,et al.Experimental study on flash boiling characteristics of different boiling point fuels and their mixtures[J].Transactions of CSICE,2014,32(4):316-321(in Chinese).
[2]段树林,冯林,宋永臣,等.闪急沸腾喷雾场粒度分布规律及燃烧特性的研究[J].内燃机学报,1999,17(1):54-58.Duan Shulin,Feng Lin,Song Yongchen,et al.Study on particle size distribution and combustion characteristics of flash boiling spray field[J].Transactions of CSICE,1999,17(1):54-58(in Chinese).
[3]Gele A,Hung D.Effect of nozzle configuration on macroscopic spray characteristics of multi-hole fuel injectors under superheated conditions[J].Atomization&Sprays,2016,26(5):439-462.
[4]Noyori T.Experimental study of smoke emission on small-displacement spark-ignition direct-injection engine[C]//SAE Technical Paper.Detroit,USA,2006:2006-32-0105.
[5]Dahms R N,Oefelein J C.Liquid jet breakup regimes at supercritical pressures[J].Combustion&Flame,2015,162(10):3648-3657.
[6]Boer C D,Chang J,Shetty S.Transonic combustionA novel injection-ignition system for improved gasoline engine efficiency[C]//SAE 2010 Powertrains Fuels&Lubricants Meeting.Detroit,USA,2010:559-561.
[7]Boer C D,Bonar G,Sasaki S,et al.Application of supercritical gasoline injection to a direct injection spark ignition engine for particulate reduction[C]//SAE Technical Paper.Detroit,USA,2013:2013-01-0257.
[8]Nishida K,Tian J,Sumoto Y,et al.An experimental and numerical study on sprays injected from two-hole nozzles for DISI engines[J].Fuel,2009,88:1634-1642.
[9]Nishida K,Gao J,Matsumoto Y.Experimental study on spray and mixture properties of the group-hole nozzle for direct-injection diesel engines,part II:Effects of included angle and interval between orifices[J].Atomization and Sprays,2009,19(4):339-355.
[10]Van Romunde Z,Aleiferis P G.Effect of operating conditions and fuel volatility on development and variability of sprays from gasoline direct-injection multi-hole injectors[J].Atomization and Sprays,2009,19(3):207-234.
[11]Aleiferis P G,van Romunde Z R.An analysis of spray development with iso-octane,n-pentane,gasoline,ethanol and n-butanol from a multi-hole injector under hot fuel conditions[J].Fuel,2012,105:143-168.
[12]Guo H,Ding H,Li Y,et al.Comparison of spray collapses at elevated ambient pressure and flash boiling conditions using multi-hole gasoline direct injector[J].Fuel,2017,199:125-134.
[13]邓鹏,黄荣华,马寅杰,等.强化混合条件下乙醇柴油和柴油的喷雾混合特性[J].内燃机学报,2014,32(2):144-151.Deng Peng,Huang Ronghua,Ma Yinjie,et al.Spray mixing characteristics of ethanol diesel and diesel under intensive mixing conditions[J].Transactions of CSICE,2014,32(2):144-151(in Chinese).
[14]裴毅强,王琨,张丹,等.GDI喷油器超高压乙醇喷雾的宏观特性[J].天津大学学报:自然科学与工程技术版,2018,51(7):755-762.Pei Yiqiang,Wang Kun,Zhang Dan,et al.Spray macroscopic characteristics of GDI injector fueled with ethanol using ultra-high injection pressure[J].Journal of Tianjin University:Science and Technology,2018,51(7):755-762(in Chinese).
[15]Hung D L S,Harrington D L,Gandhi A H,et al.Gasoline fuel injector spray measurement and characterization-A new SAE J2715 recommended practice[J].SAE International Journal of Fuels&Lubricants,2008,1(1):534-548.
[16]Lin Ronghong,Tavlarides L L.Thermophysical properties needed for the development of the supercritical diesel combustion technology:Evaluation of diesel fuel surrogate models[J].The Journal of Supercritical Fluids,2012,71:136-146.
[17]马沛生.石油化工基础数据手册[M].北京:化学工业出版社,1993.Ma Peisheng.Basic Data Handbook of Petrochemical Industry[M].Beijing:Chemical Industry Press,1993(in Chinese).
[18]张淼,裴毅强,郑朝蕾,等.亚临界/超临界汽油喷雾特性[J].内燃机学报,2015,33(5):420-425.Zhang Miao,Pei Yiqiang,Zheng Chaolei,et al.Characteristics of sub-supercritical gasoline spray[J].Transactions of CSICE,2015,33(5):420-425(in Chinese).
[19]解茂昭.内燃机跨临界/超临界燃料喷雾混合过程的机理与模型[J].燃烧科学与技术,2014,20(1):1-9.Xie Maozhao.Mechanism and model of crosscritical/supercritical fuel spray mixing process for internal combustion engines[J].Journal of Combustion Science and Technology,2014,20(1):1-9(in Chinese).
[20]姚卓,王天友,杨晟华,等.不同沸点燃料及其混合物的闪沸喷雾特性试验[J].内燃机学报,2014,32(4):316-321.Yao Zhuo,Wang Tianyou,Yang Chenghua,et al.Experimental study on flash boiling characteristics of different boiling point fuels and their mixtures[J].Transactions of CSICE,2014,32(4):316-321(in Chinese).