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
应用计算流体力学(CFD)软件对一台带有废气再循环(Exhaust gas recirculation,EGR)系统的均质缸内直喷(Gasoline direct-injection,GDI)汽油机进气冲程至作功冲程排气门开启时段进行了三维仿真,研究了不同EGR率和过量空气系数λ对缸内...应用计算流体力学(CFD)软件对一台带有废气再循环(Exhaust gas recirculation,EGR)系统的均质缸内直喷(Gasoline direct-injection,GDI)汽油机进气冲程至作功冲程排气门开启时段进行了三维仿真,研究了不同EGR率和过量空气系数λ对缸内状态及排放特性的影响,探讨了温度场、火焰面密度、NO浓度场、CO浓度场、微粒浓度场等参数的变化趋势。结果表明:EGR率为10%时,能在对燃烧过程影响不大的情况下有效降低排放质量;同时,在缸压稍有下降的情况下,λ=1.1时能有效降低排放质量;λ=1.0时能保持较高的缸压和中等的排放水平。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.
文摘应用计算流体力学(CFD)软件对一台带有废气再循环(Exhaust gas recirculation,EGR)系统的均质缸内直喷(Gasoline direct-injection,GDI)汽油机进气冲程至作功冲程排气门开启时段进行了三维仿真,研究了不同EGR率和过量空气系数λ对缸内状态及排放特性的影响,探讨了温度场、火焰面密度、NO浓度场、CO浓度场、微粒浓度场等参数的变化趋势。结果表明:EGR率为10%时,能在对燃烧过程影响不大的情况下有效降低排放质量;同时,在缸压稍有下降的情况下,λ=1.1时能有效降低排放质量;λ=1.0时能保持较高的缸压和中等的排放水平。
