The development of the injector nozzle is a dynamic area in regard of several technical aspects. At first, the internal flow influences the near-field spray characteristics via various phenomena such as cavitation and turbulence. However, these phenomena are not fully understood due to their extremely fast, complex and multiscale nature. Furthermore, it governs the spray targeting inside the combustion chamber. High-speed X-ray imaging of GDI injector nozzles is performed in this study. The experimental results presented are related to the internal flow and primary breakup of discharged liquid jets. The injectors used are equipped with nozzles made of aluminum which have been specially developed for these investigations to enhance optical accessibility. The visualization of the needle motion, in-nozzle flow and the primary breakup region provides several exciting observations. First, the needle lift tracking exhibits short overshooting right before the steady-state of the injection phase. This event leads to a short-term, however, significant change in the associated performance of the breakup. This phenomenon is found to be a consequence of the transient behavior of the in-nozzle flow. It is shown that under some circumstances hydraulic flip may occur during this overshooting period. The primary jet breakup region is visualized and evaluated by means of image processing. Thus, the transient behavior of liquid jet expansion is quantified in the vicinity of the nozzle. It is observed that the liquid jet direction deviates from the hole axis already at the nozzle outlet, which is caused by internal flow characteristics.

就几个技术方面而言，喷嘴的发展是一个动态领域。首先，内部流动会通过各种现象（例如空化和湍流）影响近场喷雾特性。但是，由于这些现象极其快速，复杂和多尺度，因此尚未完全理解。此外，它控制燃烧室内的喷雾目标。在这项研究中进行了GDI喷油嘴的高速X射线成像。给出的实验结果与排出的液体射流的内部流动和一次破裂有关。所使用的注射器配有铝制喷嘴，这些喷嘴是专门为这些研究而开发的，以增强光学可及性。可视化的针运动，喷嘴内流动和主要破裂区域提供了一些令人兴奋的观察结果。首先，在进样阶段的稳态之前，针升程跟踪显示出短暂的超调。但是，此事件会导致短期内分手的相关性能发生重大变化。发现该现象是喷嘴内流动的瞬态行为的结果。结果表明，在某些情况下，在该超调期间可能发生液压翻转。通过图像处理可视化和评估主喷嘴的破裂区域。因此，在喷嘴附近量化了液体射流膨胀的瞬态行为。可以观察到，由于内部流动特性，液体喷射方向已经偏离喷嘴出口处的孔轴线。