超高压喷射条件下非常态燃油缸内喷雾特性
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摘要
为了研究超高压喷射条件下缸内非常态燃油的雾化特性,分析非常态燃油各个物性参数与压力之间的关系;搭建可视化喷雾闪光摄影试验台架,在AVL FIRE平台上对喷雾过程进行三维数值仿真;利用喷雾发展的试验结果验证仿真模型的准确性,并研究喷射背压、喷孔直径对燃油雾化特性的影响。研究结果表明:在超高压喷射条件下,燃油密度、音速和弹性模量的增大有利于油滴在喷嘴出口处获得较大的湍动能,进一步提高燃油的雾化质量;喷射背压增大时油束与缸内空气之间的能量交换加剧,射流扰动增强,加剧了油滴的二次破碎;随着喷孔直径增大,油束的初始湍动能增加,有助于气态燃油向燃烧室四周和底部扩散发展。
In order to study the atomization characteristics of non-normal fuel in-cylinder under the condition of super-high pressure injection, the relationship between physical properties of non-normal fuel and pressure was analyzed.Visual spray flash photography test bench was set up. Three-dimensional numerical simulation of spraying process was completed on AVL FIRE software platform. The accuracy of the simulation model was verified by the experimental results of spray development. The influences of injection back pressures and nozzle diameters on atomization characteristics were studied. The results show that under the condition of super-high pressure injection, the increase of fuel density, sound velocity and elasticity modulus is good for the oil beams to obtain a better jet state at the outlet of nozzle, which further improves the quality of atomization. With the increase of injection back pressure, energy exchange between the oil beams and air becomes more intense, which enhances the jets disturbance and catalyzes the secondary broken of oil droplet. With the increase of nozzle diameter, initial turbulent kinetic energy of oil beams increases, which is helpful for the diffusion development of gaseous fuel to the surrounding and the bottom of combustion chamber.
In order to study the atomization characteristics of non-normal fuel in-cylinder under the condition of super-high pressure injection, the relationship between physical properties of non-normal fuel and pressure was analyzed.Visual spray flash photography test bench was set up. Three-dimensional numerical simulation of spraying process was completed on AVL FIRE software platform. The accuracy of the simulation model was verified by the experimental results of spray development. The influences of injection back pressures and nozzle diameters on atomization characteristics were studied. The results show that under the condition of super-high pressure injection, the increase of fuel density, sound velocity and elasticity modulus is good for the oil beams to obtain a better jet state at the outlet of nozzle, which further improves the quality of atomization. With the increase of injection back pressure, energy exchange between the oil beams and air becomes more intense, which enhances the jets disturbance and catalyzes the secondary broken of oil droplet. With the increase of nozzle diameter, initial turbulent kinetic energy of oil beams increases, which is helpful for the diffusion development of gaseous fuel to the surrounding and the bottom of combustion chamber.
引文
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[16]汪洋,谢辉,苏万华,等.共轨式电控喷射系统控制参数对柴油机燃烧过程及排放的影响[J].燃烧科学与技术,2002,8(3):258-261.WANG Yang,XIE Hui,SU Wanhua,et al.Investigation on the effects of controllable parameters of the common-rail injection system on the combustion process and emission in a diesel engine[J].Journal of Combustion Science and Technology,2002,8(3):258-261.
[17]袁文华,鄂加强,龚金科,等.气缸压力监测下车用多缸发动机燃烧状况分析系统[J].中南大学学报(自然科学版),2006,37(4):763-768.YUAN Wenhua,E Jiaqiang,GONG Jinke,et al.Combustion condition analysis system of vehicle engine with multi-cylinder under cylinder pressure monitoring[J].Journal of Central South University(Science and Technology),2006,37(4):763-768.
[2]PAYRI F,GARCIA J M,SALVADOR F J,et al.Using spray monentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics[J].Fuel,2005,84(2):551-561.
[3]王艳华,杨世春,高峰,等.汽油缸内多孔直喷喷雾破碎模型建立于试验[J].农业机械学报,2013,44(3):12-16.WANG Yanhua,YANG Shichun,GAO Feng,et al.Spray break-up model establishment and experiment of multi-hole injector on gasoline direct injection engine[J].Transactions of the Chinese Society for Agricultural Machinery,2013,44(3):12-16.
[4]王钧效,陆家祥,王桂华,等.柴油机燃油物性参数的研究[J].内燃机学报,2001,19(6):507-510.WANG Junxiao,LU Jiaxiang,WANG Guihua,et al.Study on physical characters parameters of fuel used in diesel engines[J].Transactions of CSICE,2001,19(6):507-510.
[5]BOBAN D N,BREDA K,SASA D M,et al.Determining the speed of sound,density,and bulk modulus of rapeseed oil,biodiesel,and diesel fuel[J].Thermal Science,2012,16(9):505-514.
[6]邵利民.高压共轨燃油喷雾特性的试验研究模型验证[J].车用发动机,2005,171(5):44-51.SHAO Limin.Experimental study and model modification on high pressure common rail fuel spray characteristics[J].Vehicle Engine,2005,171(5):44-51.
[7]孙柏刚,张大鹏,冯旺聪.高压共轨燃油喷雾PIV测试方法及结果分析[J].北京理工大学学报,2006,26(7):574-576.SUN Baigang,ZHANG Dapeng,FENG Wangcong.Particle image velocimetry test methods for high pressure common rail spray and results of analysis[J].Transactions of Beijing Institute of Technology,2006,26(7):574-576.
[8]MACIAN V,PAYRI R,RUIZ S,et al.Experimental study of the relationship between injection rate shape and Diesel ignition using a novel piezo-actuated direct acting injector[J].Applied Energy,2014,118(1):100-113.
[9]LUCKHCHOURA V,PETERS N,DIWAKAR R.Computational analysis of injection-rate shapes in a small-bore direct-injection diesel engine[J].International Journal of Engine Research,2011,12(2):145-168.
[10]周乃君,杨晓力,邢志海,等.高压共轨燃油喷射雾化特性的数值预报[J].中南大学学报(自然科学版),2012,43(10):4063-4067.ZHOU Naijun,YANG Xiaoli,XING Zhihai,et al.Numerical simulation on spray characteristics of high pressure common rail system[J].Journal of Central South University(Science and Technology),2012,43(10):4063-4067.
[11]刘琦,欧阳光耀,杨昆,等.高压喷射条件下非常态燃油喷嘴内部空化流动特性[J].农业机械学报,2016,47(5):333-339.LIU Qi,OUYANG Guangyao,YANG Kun,et al.Nozzle inner cavitation flow characteristics of non-normal fuel based on high pressure injection condition[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(6):333-339.
[12]黄康,欧阳光耀,安士杰,等.双层交错布置多孔喷嘴燃烧排放性能试验研究[J].内燃机工程,2015,45(4):2617-2623.HUANG Kang,OUYANG Guangyao,AN Shijie,et al.Experimental research of combustion and emission of double-staggered arranged porous nozzle.[J].Chinese Internal Combustion Engine Engineering,2015,45(4):2617-2623
[13]周磊,解茂昭,贾明,等.发动机早喷过程中燃油喷射混合的大涡模拟[J].中南大学学报(自然科学版),2012,43(9):3678-3686.ZHOU Lei,XIE Maozhao,JIA Ming,et al.Large eddy simulation for fuel injection and mixing of early-injection in diesel engine[J].Journal of Central South University(Science and Technology),2012,43(9):3678-3686.
[14]BENAJES J,PAYRI R,MOLINA S,et al.Investigation of the influence of injection rate shaping on the spray characteristics in a diesel common rail system equipped with a piston amplifier[J].Journal of Fluids Engineering,2005,127(6):1102-1110.
[15]LEONHARD R,WARGA J.2000 bar Diesel Common Rail by Bosch for passenger cars[J].MTZ Worldwide,2008,69(10):26-31.
[16]汪洋,谢辉,苏万华,等.共轨式电控喷射系统控制参数对柴油机燃烧过程及排放的影响[J].燃烧科学与技术,2002,8(3):258-261.WANG Yang,XIE Hui,SU Wanhua,et al.Investigation on the effects of controllable parameters of the common-rail injection system on the combustion process and emission in a diesel engine[J].Journal of Combustion Science and Technology,2002,8(3):258-261.
[17]袁文华,鄂加强,龚金科,等.气缸压力监测下车用多缸发动机燃烧状况分析系统[J].中南大学学报(自然科学版),2006,37(4):763-768.YUAN Wenhua,E Jiaqiang,GONG Jinke,et al.Combustion condition analysis system of vehicle engine with multi-cylinder under cylinder pressure monitoring[J].Journal of Central South University(Science and Technology),2006,37(4):763-768.