An on-going challenge with Gasoline direct injection (GDI) engines is achieving rapid activation of the exhaust catalyst during cold starts, in order to reduce the Nitrogen Oxide (NOx) emissions. Injecting late in the compression stroke, in the efforts to form a stratified mixture, provides the fuel insufficient time to be entrained with the surrounding charge. This results in locally fuel rich diffusion combustion and the formation of high levels of particulate matter. Employing a split injection strategy can help tackle these issues. The current study examines the effects of a split injection strategy on the spray characteristics. Varying pulse width (PW) combinations, split ratios and dwell times are investigated using a Solenoid actuated high pressure injector. The injected quantity and the droplet characteristics of a target plume are investigated. The experiments were performed in a constant volume spray chamber. The droplet velocities and sizes were measured using Phase Doppler Particle Anemometry (PDA). Short and large PWs, in the range of 0.3–0.8 ms, were investigated. The results revealed that the highest injected quantity of fuel was measured with the shortest dwell time of 2 ms, owing to increased interactions between the injection events, which led to larger Sauter mean diameters (SMDs) measured. The SMDs for the shorter PW of 0.4 ms were generally larger than 0.8 ms PW. The droplets in this case were affected by the closely spaced opening and closing events of the Solenoid valve.

汽油直喷（GDI）发动机所面临的挑战是在冷启动期间实现排气催化剂的快速活化，以减少氮氧化物（NOx）的排放。为了形成分层混合物，在压缩冲程的后期进行喷射提供了燃料不足的时间以被周围的装料夹带。这导致局部富燃料扩散燃烧并形成高水平的颗粒物质。采用拆分注入策略可以帮助解决这些问题。当前的研究检查了分流喷射策略对喷雾特性的影响。使用电磁阀致动的高压注射器研究了各种脉冲宽度（PW）组合，分流比和停留时间。研究了目标羽流的喷射量和液滴特性。实验在恒定体积的喷雾室中进行。使用相多普勒粒子风速仪（PDA）测量液滴的速度和大小。研究了短和大PW，范围为0.3-0.8 ms。结果显示，由于喷射事件之间的相互作用增加，因此以2 ms的最短停留时间测量了最高的燃料喷射量，这导致所测得的Sauter平均直径（SMD）更大。较短PW（0.4毫秒）的SMD通常大于0.8毫秒（PW）。在这种情况下，液滴受到电磁阀的紧密间隔开闭事件的影响。使用相多普勒粒子风速仪（PDA）测量液滴的速度和大小。研究了短和大PW，范围为0.3-0.8 ms。结果显示，由于喷射事件之间的相互作用增加，因此以2 ms的最短停留时间测量了最高的燃料喷射量，这导致所测得的Sauter平均直径（SMD）更大。较短PW（0.4毫秒）的SMD通常大于0.8毫秒（PW）。在这种情况下，液滴受电磁阀的紧密间隔开闭事件的影响。使用相多普勒粒子风速仪（PDA）测量液滴的速度和大小。研究了短和大PW，范围为0.3-0.8 ms。结果显示，由于喷射事件之间的相互作用增加，因此以2 ms的最短停留时间测量了最高的燃料喷射量，这导致所测得的Sauter平均直径（SMD）更大。较短PW（0.4毫秒）的SMD通常大于0.8毫秒（PW）。在这种情况下，液滴受到电磁阀的紧密间隔开闭事件的影响。由于进样事件之间的相互作用增加，导致更大的Sauter平均直径（SMD）。较短PW（0.4毫秒）的SMD通常大于0.8毫秒（PW）。在这种情况下，液滴受到电磁阀的紧密间隔开闭事件的影响。由于进样事件之间的相互作用增加，导致更大的Sauter平均直径（SMD）得以测量。较短PW（0.4毫秒）的SMD通常大于0.8毫秒（PW）。在这种情况下，液滴受到电磁阀的紧密间隔开闭事件的影响。