The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually ...The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually and the turbulence kinetic energy（TKE）was small in the compression process;however,tumble was strengthened and the TKE was strong in the compression process.For swirl around X axis（the axis of cylinder）and tumble around Y axis（the vertical direction of injector）,droplets were attached to the cylinder liner by the centrifugal force and the mixture distribution was poor.For tumble around Zaxis（the direction of injector）,the wall film in cylinder liner was thin and mixture distribution was homogeneous.Results showed that since the injector were installed on the wall of the cylinder liner in the OPTS-GDI engine,the spray angle was small and the mixture formation time was short.The 45° oblique axis tumble ratio of 1 was reasonable for the mixture formation and combustion for an OPTS-GDI engine.展开更多
In order to improve the fuel consumption and exhaust emission for gasoline engines,gasoline direct injection（GDI） system is spotlighted to solve these requirements.Thus,many researchers focus on the investigation of...In order to improve the fuel consumption and exhaust emission for gasoline engines,gasoline direct injection（GDI） system is spotlighted to solve these requirements.Thus,many researchers focus on the investigation of spray characteristics and the fuel formation of GDI injector.This paper presents a complete numerical and experimental characterization of transient gasoline spray from a high pressure injection system equipped with a modern single-hole electric controlled injector in a pressurized constant volume vessel.The numerical analysis is carried out in a one-dimensional model of fuel injection system which is developed in the AVL HYDSIM environment.The experimental analyses are implemented through a self-developed injection rate measurement device and spray evolution visualization system.The experimental results of injection rate and spray dynamics are taken to tune and validate the built model.The visualization system synchronize a high speed CMOS camera to obtain the spray structure,moreover,the captured images are taken to validate the injector needle lift process which is simulated in the model.The reliability of the built model is demonstrated by comparing the numerical results with the experimental data.The formed vortex structure at 0.8 ms is effectively disintegrated at 6.2 ms and the spray dynamics become rather chaotic.The fuel flow characteristics within injector nozzle extremely influence the subsequent spray evolution,and therefore this point should be reconsidered when building hybrid breakup GDI spray model.The spray tip speed reach the maximum at 1.18 ms regardless of the operation conditions and this is only determined by the injector itself.Furthermore,an empirical equation for the spray tip penetration is obtained and good agreement with the measured results is reached at a certain extent.This paper provides a methodology for the investigation of spray behavior and fuel distribution of GDI engine design.展开更多
缸内直喷汽油机(gasoline direct injection,GDI)的颗粒物排放问题越来越引起人们的重视。为解析GDI汽油机缸内碳烟生成机理,文中提出了一种改进的两步法碳烟模型,将该模型应用于Kiva-Chemkin软件中,对一款典型GDI汽油机的喷雾碰壁、混...缸内直喷汽油机(gasoline direct injection,GDI)的颗粒物排放问题越来越引起人们的重视。为解析GDI汽油机缸内碳烟生成机理,文中提出了一种改进的两步法碳烟模型,将该模型应用于Kiva-Chemkin软件中,对一款典型GDI汽油机的喷雾碰壁、混合气形成、燃烧和碳烟生成过程进行了三维计算流体力学(CFD)数值模拟。结果表明,GDI汽油机的碳烟主要源于缸内油气混合不均、壁面油膜的燃烧即池火燃烧。在均质混合气工作模式下,增加喷油提前角可使燃油雾化更好、油气混合均匀,从而降低碳烟生成。但如果喷油提前角过大,会导致喷雾碰壁,引起碳烟生成量急剧增加。在分层混合气工作模式下,碳烟主要来源于局部浓区。过早喷油不利于产生喷雾诱导的滚流,不利于油气均匀混合,会产生局部燃油浓区,从而导致缸内碳烟生成量较高。结果表明,文中提出的碳烟模型可较好地预测缸内碳烟生产过程。展开更多
汽油直喷(Gasoline direct injection,GDI)喷油器性能受温升影响较大,限制了发动机电子控制单元(Electronic control unit,ECU)对其喷油量的控制精度。针对GDI喷油器电、磁、热子系统之间的耦合关系,建立了耦合过程的物理模型,通过研究...汽油直喷(Gasoline direct injection,GDI)喷油器性能受温升影响较大,限制了发动机电子控制单元(Electronic control unit,ECU)对其喷油量的控制精度。针对GDI喷油器电、磁、热子系统之间的耦合关系,建立了耦合过程的物理模型,通过研究GDI喷油器工作过程中能量损耗及转化关系,揭示了电磁转化过程中产生的损耗是造成喷油器本体温升的主要原因。以电磁转化过程中能量损耗为热源,以热辐射和热传导基本理论为依据,利用ANSYS有限元软件对GDI喷油器温度场进行仿真分析,并进行了试验验证,分析了GDI喷油器本体温度场分布特点以及温升变化对喷油器性能的影响规律。结果表明,线圈和铁芯部分的温升较高,随温度升高GDI喷油器动态响应时间延长、喷油量减少,且温升受保持电流和保持脉宽的影响较大。展开更多
基金Supported by the National Natural Science Foundation of China(B2220110005)
文摘The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually and the turbulence kinetic energy（TKE）was small in the compression process;however,tumble was strengthened and the TKE was strong in the compression process.For swirl around X axis（the axis of cylinder）and tumble around Y axis（the vertical direction of injector）,droplets were attached to the cylinder liner by the centrifugal force and the mixture distribution was poor.For tumble around Zaxis（the direction of injector）,the wall film in cylinder liner was thin and mixture distribution was homogeneous.Results showed that since the injector were installed on the wall of the cylinder liner in the OPTS-GDI engine,the spray angle was small and the mixture formation time was short.The 45° oblique axis tumble ratio of 1 was reasonable for the mixture formation and combustion for an OPTS-GDI engine.
基金supported by China First Auto Works Group Corporation R&D Center Program (Grant No. 56067028)
文摘In order to improve the fuel consumption and exhaust emission for gasoline engines,gasoline direct injection（GDI） system is spotlighted to solve these requirements.Thus,many researchers focus on the investigation of spray characteristics and the fuel formation of GDI injector.This paper presents a complete numerical and experimental characterization of transient gasoline spray from a high pressure injection system equipped with a modern single-hole electric controlled injector in a pressurized constant volume vessel.The numerical analysis is carried out in a one-dimensional model of fuel injection system which is developed in the AVL HYDSIM environment.The experimental analyses are implemented through a self-developed injection rate measurement device and spray evolution visualization system.The experimental results of injection rate and spray dynamics are taken to tune and validate the built model.The visualization system synchronize a high speed CMOS camera to obtain the spray structure,moreover,the captured images are taken to validate the injector needle lift process which is simulated in the model.The reliability of the built model is demonstrated by comparing the numerical results with the experimental data.The formed vortex structure at 0.8 ms is effectively disintegrated at 6.2 ms and the spray dynamics become rather chaotic.The fuel flow characteristics within injector nozzle extremely influence the subsequent spray evolution,and therefore this point should be reconsidered when building hybrid breakup GDI spray model.The spray tip speed reach the maximum at 1.18 ms regardless of the operation conditions and this is only determined by the injector itself.Furthermore,an empirical equation for the spray tip penetration is obtained and good agreement with the measured results is reached at a certain extent.This paper provides a methodology for the investigation of spray behavior and fuel distribution of GDI engine design.
文摘缸内直喷汽油机(gasoline direct injection,GDI)的颗粒物排放问题越来越引起人们的重视。为解析GDI汽油机缸内碳烟生成机理,文中提出了一种改进的两步法碳烟模型,将该模型应用于Kiva-Chemkin软件中,对一款典型GDI汽油机的喷雾碰壁、混合气形成、燃烧和碳烟生成过程进行了三维计算流体力学(CFD)数值模拟。结果表明,GDI汽油机的碳烟主要源于缸内油气混合不均、壁面油膜的燃烧即池火燃烧。在均质混合气工作模式下,增加喷油提前角可使燃油雾化更好、油气混合均匀,从而降低碳烟生成。但如果喷油提前角过大,会导致喷雾碰壁,引起碳烟生成量急剧增加。在分层混合气工作模式下,碳烟主要来源于局部浓区。过早喷油不利于产生喷雾诱导的滚流,不利于油气均匀混合,会产生局部燃油浓区,从而导致缸内碳烟生成量较高。结果表明,文中提出的碳烟模型可较好地预测缸内碳烟生产过程。
文摘汽油直喷(Gasoline direct injection,GDI)喷油器性能受温升影响较大,限制了发动机电子控制单元(Electronic control unit,ECU)对其喷油量的控制精度。针对GDI喷油器电、磁、热子系统之间的耦合关系,建立了耦合过程的物理模型,通过研究GDI喷油器工作过程中能量损耗及转化关系,揭示了电磁转化过程中产生的损耗是造成喷油器本体温升的主要原因。以电磁转化过程中能量损耗为热源,以热辐射和热传导基本理论为依据,利用ANSYS有限元软件对GDI喷油器温度场进行仿真分析,并进行了试验验证,分析了GDI喷油器本体温度场分布特点以及温升变化对喷油器性能的影响规律。结果表明,线圈和铁芯部分的温升较高,随温度升高GDI喷油器动态响应时间延长、喷油量减少,且温升受保持电流和保持脉宽的影响较大。
