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
As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI...As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI injectors are an important application prerequisite.In this paper,the computational fluid dynamics(CFD)software AVL Fire is employed to study the spray characteristics.Two types of spray models are established based on the Han Sheet model and the KH-RT model,and simulation works are carried out according to two types of spray tests in the literature.The comparison results show that in the constant volume bomb test,the spray patterns obtained by simulation under the two sets of environmental pressures are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray contraction of the near nozzle field and the vortex of the far nozzle field better.In the tube test,the spray patterns obtained by simulation under the five sets of flow velocity are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray expansion and the vortex of the far nozzle field better.The RP-3 kerosene spray characteristics of the self-pressurized injector are also experimentally studied,and the results demonstrate that due to the higher viscosity of kerosene,the spray shrinks more easily,resulting in a smaller spray cone angle and larger penetration.Therefore,changes in environmental pressure have greater impact on the kerosene spray pattern.展开更多
利用激光粒度仪分析了空气辅助喷射喷雾索特平均直径(Sauter mean diameter,SMD)的变化规律,并且分别在定容弹及光学发动机上开展了喷雾特性(喷雾锥角和贯穿距离)的试验研究,引入喷雾半锥角(α角和β角)的概念用以分析在有进气气流时空...利用激光粒度仪分析了空气辅助喷射喷雾索特平均直径(Sauter mean diameter,SMD)的变化规律,并且分别在定容弹及光学发动机上开展了喷雾特性(喷雾锥角和贯穿距离)的试验研究,引入喷雾半锥角(α角和β角)的概念用以分析在有进气气流时空气喷射量对喷雾特性的影响.结果表明,增加空气喷射量可以改善燃油的雾化效果,特别是当喷雾燃空比γ小于0.8时,喷雾的SMD会有明显降低;在定容弹内空气喷射量的增大会使喷雾锥角减小,但对贯穿距离的影响不大;在光学发动机内由于进气气流的影响,空气喷射量的增加会使喷雾锥角增大,贯穿距离变小,同时喷雾锥角随时间的变化趋势也明显不同于定容弹内的试验结果.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(No.51865031)the State Key Laboratory of Engines of Tianjin University(No.K2020-05)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJB470014)。
文摘As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI injectors are an important application prerequisite.In this paper,the computational fluid dynamics(CFD)software AVL Fire is employed to study the spray characteristics.Two types of spray models are established based on the Han Sheet model and the KH-RT model,and simulation works are carried out according to two types of spray tests in the literature.The comparison results show that in the constant volume bomb test,the spray patterns obtained by simulation under the two sets of environmental pressures are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray contraction of the near nozzle field and the vortex of the far nozzle field better.In the tube test,the spray patterns obtained by simulation under the five sets of flow velocity are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray expansion and the vortex of the far nozzle field better.The RP-3 kerosene spray characteristics of the self-pressurized injector are also experimentally studied,and the results demonstrate that due to the higher viscosity of kerosene,the spray shrinks more easily,resulting in a smaller spray cone angle and larger penetration.Therefore,changes in environmental pressure have greater impact on the kerosene spray pattern.
文摘利用激光粒度仪分析了空气辅助喷射喷雾索特平均直径(Sauter mean diameter,SMD)的变化规律,并且分别在定容弹及光学发动机上开展了喷雾特性(喷雾锥角和贯穿距离)的试验研究,引入喷雾半锥角(α角和β角)的概念用以分析在有进气气流时空气喷射量对喷雾特性的影响.结果表明,增加空气喷射量可以改善燃油的雾化效果,特别是当喷雾燃空比γ小于0.8时,喷雾的SMD会有明显降低;在定容弹内空气喷射量的增大会使喷雾锥角减小,但对贯穿距离的影响不大;在光学发动机内由于进气气流的影响,空气喷射量的增加会使喷雾锥角增大,贯穿距离变小,同时喷雾锥角随时间的变化趋势也明显不同于定容弹内的试验结果.
