The nozzle inner-flow characteristic of the“spray G”injector was studied by the computational fluid dynamics(CFD)simulation,and the sensitivity of cycle fuel mass to the conicity and entrance radius of the nozzle ho...The nozzle inner-flow characteristic of the“spray G”injector was studied by the computational fluid dynamics(CFD)simulation,and the sensitivity of cycle fuel mass to the conicity and entrance radius of the nozzle hole were analyzed.Results show that the inner conicity of nozzle hole inhibits the development of cavitation phenomena,and increases the injection rate.While the outer conicity of nozzle hole promotes the diffusion of cavita-tion,leading to reductions of the liquid volume fraction of the nozzle outlet and the local flow resistance of the nozzle hole.The sensitivity of cycle fuel mass to inner-cone nozzle hole is stronger than that of the outer-cone noz-zle,especially at the smaller hole conicity.The increase of injection pressure enhances the sensitivity of the injection characteristics to the nozzle hole structure,in which inner-cone nozzle has higher sensitivity coefficient than the outer-cone nozzle hole.However,the increase of injection pressure aggravates the offset of liquid jet to the nozzle axis of the outer-cone nozzle hole.With the increase of the inner conicity of nozzle,the sensitivity of the injection characteristics to the entrance radius of the hole decreases.With the increase of the outer conicity of nozzle hole,the sensitivity of the injection characteristics to the entrance radius of the hole increases.展开更多
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
为预测高原环境下缸内直喷(Gasoline Direct Injection, GDI)汽油车CO和PN的瞬时排放量,开发并评估了一套基于深度学习的排放预测模型。利用便携式车载排放测试系统对一辆GDI汽油车进行实际道路排放测试;加入奇异谱分析对原始时间序列...为预测高原环境下缸内直喷(Gasoline Direct Injection, GDI)汽油车CO和PN的瞬时排放量,开发并评估了一套基于深度学习的排放预测模型。利用便携式车载排放测试系统对一辆GDI汽油车进行实际道路排放测试;加入奇异谱分析对原始时间序列进行处理,剔除时间序列中的异常值;利用XGBoost模型对GDI汽油车的CO和PN的瞬时排放进行初步预测,并利用SVR模型进行残差修正得到最终的预测结果。将预测结果与实际道路排放试验中使用PEMS设备测量的实际值进行比较,结果表明,XGBoost-SVR排放预测模型能较好地预测GDI汽油车瞬时CO和PN的排放,相比单一的XGBoost模型,RMSE分别提高了22.9%和39.7%,决定系数R2均大于0.9,支持预测结果的可靠性。该模型对监测高原环境下GDI汽油车实际道路排放具有一定的工程意义。展开更多
采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于...采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于圆形喷孔,当喷射压力为15.0 MPa时,椭圆喷孔长短轴比为4的椭圆喷孔E2中异辛烷质量流量要比圆形喷孔大3.54%;在喷雾贯穿阶段,由于椭圆喷雾贯穿距离始终小于圆形喷雾,导致椭圆喷雾撞击壁面的时间延迟,当喷射压力为6.0 MPa时,椭圆喷孔E2的喷雾撞壁时间较圆形喷雾推迟0.14 ms;喷雾撞击壁面后,圆形喷雾的铺展半径和卷吸高度都要大于椭圆喷雾,这是因为圆形喷雾速度快,喷雾动量大,促进了喷雾的飞溅和反弹,但这种差异随着喷射压力的提高而减小.展开更多
As one of the most important actuators for gasoline direct injection technology,common rail systems provide the requested rail pressure for fuel injection.Special system characteristics,such as coupled discrete-contin...As one of the most important actuators for gasoline direct injection technology,common rail systems provide the requested rail pressure for fuel injection.Special system characteristics,such as coupled discrete-continuous dynamic in the common rail system,limited measurable states,and time-varying engine operating conditions,impel the combination of advanced methods to obtain the desired injection pressure.Therefore,reducing the pressure fluctuation and satisfying engineering implementation have become noteworthy issues for rail pressure control(RPC)systems.In this study,the benchmark problem and the design specification of RPC proposed by 2018 IFAC E-CoSM Committee are introduced.Moreover,a common rail system model is provided to the challengers,and a traditional PI control is applied to show the problem behaviors.Finally,intermediate results of the challengers are summarized briefly.展开更多
文摘The nozzle inner-flow characteristic of the“spray G”injector was studied by the computational fluid dynamics(CFD)simulation,and the sensitivity of cycle fuel mass to the conicity and entrance radius of the nozzle hole were analyzed.Results show that the inner conicity of nozzle hole inhibits the development of cavitation phenomena,and increases the injection rate.While the outer conicity of nozzle hole promotes the diffusion of cavita-tion,leading to reductions of the liquid volume fraction of the nozzle outlet and the local flow resistance of the nozzle hole.The sensitivity of cycle fuel mass to inner-cone nozzle hole is stronger than that of the outer-cone noz-zle,especially at the smaller hole conicity.The increase of injection pressure enhances the sensitivity of the injection characteristics to the nozzle hole structure,in which inner-cone nozzle has higher sensitivity coefficient than the outer-cone nozzle hole.However,the increase of injection pressure aggravates the offset of liquid jet to the nozzle axis of the outer-cone nozzle hole.With the increase of the inner conicity of nozzle,the sensitivity of the injection characteristics to the entrance radius of the hole decreases.With the increase of the outer conicity of nozzle hole,the sensitivity of the injection characteristics to the entrance radius of the hole increases.
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.
文摘为预测高原环境下缸内直喷(Gasoline Direct Injection, GDI)汽油车CO和PN的瞬时排放量,开发并评估了一套基于深度学习的排放预测模型。利用便携式车载排放测试系统对一辆GDI汽油车进行实际道路排放测试;加入奇异谱分析对原始时间序列进行处理,剔除时间序列中的异常值;利用XGBoost模型对GDI汽油车的CO和PN的瞬时排放进行初步预测,并利用SVR模型进行残差修正得到最终的预测结果。将预测结果与实际道路排放试验中使用PEMS设备测量的实际值进行比较,结果表明,XGBoost-SVR排放预测模型能较好地预测GDI汽油车瞬时CO和PN的排放,相比单一的XGBoost模型,RMSE分别提高了22.9%和39.7%,决定系数R2均大于0.9,支持预测结果的可靠性。该模型对监测高原环境下GDI汽油车实际道路排放具有一定的工程意义。
文摘采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于圆形喷孔,当喷射压力为15.0 MPa时,椭圆喷孔长短轴比为4的椭圆喷孔E2中异辛烷质量流量要比圆形喷孔大3.54%;在喷雾贯穿阶段,由于椭圆喷雾贯穿距离始终小于圆形喷雾,导致椭圆喷雾撞击壁面的时间延迟,当喷射压力为6.0 MPa时,椭圆喷孔E2的喷雾撞壁时间较圆形喷雾推迟0.14 ms;喷雾撞击壁面后,圆形喷雾的铺展半径和卷吸高度都要大于椭圆喷雾,这是因为圆形喷雾速度快,喷雾动量大,促进了喷雾的飞溅和反弹,但这种差异随着喷射压力的提高而减小.
基金the National Nature Science Foundation of China(Nos.61790564,61803173)the Program for Natural Science Foundation of Jilin Province(No.20190103047JH).
文摘As one of the most important actuators for gasoline direct injection technology,common rail systems provide the requested rail pressure for fuel injection.Special system characteristics,such as coupled discrete-continuous dynamic in the common rail system,limited measurable states,and time-varying engine operating conditions,impel the combination of advanced methods to obtain the desired injection pressure.Therefore,reducing the pressure fluctuation and satisfying engineering implementation have become noteworthy issues for rail pressure control(RPC)systems.In this study,the benchmark problem and the design specification of RPC proposed by 2018 IFAC E-CoSM Committee are introduced.Moreover,a common rail system model is provided to the challengers,and a traditional PI control is applied to show the problem behaviors.Finally,intermediate results of the challengers are summarized briefly.
