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
试验研究了国ⅥGDI汽油车WLTC(world light vehicle test cycle)循环的颗粒物质量和固态颗粒物数量排放特性以及颗粒物微观形貌特征。结果表明,该车颗粒物质量与固态颗粒数量排放均低于国Ⅵ法规限值;固态颗粒数量累积呈3段变化形态,0~3...试验研究了国ⅥGDI汽油车WLTC(world light vehicle test cycle)循环的颗粒物质量和固态颗粒物数量排放特性以及颗粒物微观形貌特征。结果表明,该车颗粒物质量与固态颗粒数量排放均低于国Ⅵ法规限值;固态颗粒数量累积呈3段变化形态,0~300s、600~800s与1500~1800s的累积量显著大于其他时间段。冷机起动时颗粒数量较多,仅有0~300s的累积量已大于热机起动时颗粒物数量总累积量。颗粒物主要由基本碳粒子堆积形成,形状不规则。基本碳粒子由大量微晶碳层组成,内核无序而外壳有序;重叠时有的形成大颗粒物,有的形成大碳粒子,基本碳粒子直径、碳晶长度等特征参数呈单峰分布;与GDI(gasoline direct injection)汽油机台架试验结果比较,整车试验基本碳粒子直径、碳晶长度和曲率分布相对集中且数值相对较小。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.
文摘试验研究了国ⅥGDI汽油车WLTC(world light vehicle test cycle)循环的颗粒物质量和固态颗粒物数量排放特性以及颗粒物微观形貌特征。结果表明,该车颗粒物质量与固态颗粒数量排放均低于国Ⅵ法规限值;固态颗粒数量累积呈3段变化形态,0~300s、600~800s与1500~1800s的累积量显著大于其他时间段。冷机起动时颗粒数量较多,仅有0~300s的累积量已大于热机起动时颗粒物数量总累积量。颗粒物主要由基本碳粒子堆积形成,形状不规则。基本碳粒子由大量微晶碳层组成,内核无序而外壳有序;重叠时有的形成大颗粒物,有的形成大碳粒子,基本碳粒子直径、碳晶长度等特征参数呈单峰分布;与GDI(gasoline direct injection)汽油机台架试验结果比较,整车试验基本碳粒子直径、碳晶长度和曲率分布相对集中且数值相对较小。
