Abstract This study was performed to analyze the wall impingement and fuel film formation in a DISI engine with injection strategies using image-based analysis and CFD. The direct injection engine uses a high-pressure injection strategy to improve the homogeneity of the air-fuel mixture, so the spray behavior was analyzed by spray visualization for various injection pressures, and the wall impingement was predicted for various engine operating conditions based on the acquired images. The mass distribution of the injected fuel was calculated using the injection profiles and the spray image, and the amount of fuel that impinges on the piston and wall (i.e., the geometric boundaries of the cylinder) was calculated using data from the spray behavior for various engine operation conditions such as load and engine speed. The image-based analysis was limited to understanding the influence of the injection strategy on the droplet behavior after wall impingement of the fuel spray. Therefore, CFD using KIVA 3 V code was additionally conducted to analyze the effects of the injection strategies on wall film formation and droplet rebounding reflecting in-cylinder conditions. In the early- and late-injection conditions, the initial piston position is high, and most of the injected fuel impinges on the piston. As the injection pressure increases, the injection timing at which wall impingement occurs is advanced because of the rapid spray development. The results of the 3D analysis for the temperature and the intake flow in the engine cylinder showed that both the wall impingement and the fuel film were reduced as the injection pressure increased because the fuel evaporation increased due to improved atomization.

中文翻译：

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通过分析高达 50 MPa 的高压喷射的喷雾图像预测直喷式火花点火发动机的壁面碰撞

摘要 本研究旨在使用基于图像的分析和 CFD 分析具有喷射策略的 DISI 发动机中的壁面撞击和燃料膜形成。直喷发动机采用高压喷射策略来提高空气-燃料混合物的均匀性，因此通过喷射可视化分析了各种喷射压力下的喷射行为，并基于喷射量预测了各种发动机工况下的壁面碰撞。获得的图像。使用喷射曲线和喷射图像计算喷射燃料的质量分布，并使用来自各种喷射行为的数据计算撞击活塞和壁（即气缸的几何边界）的燃料量。发动机运行条件，如负载和发动机转速。基于图像的分析仅限于了解喷射策略对燃料喷雾壁撞击后液滴行为的影响。因此，另外进行了使用 KIVA 3 V 代码的 CFD 以分析喷射策略对壁膜形成和反映缸内条件的液滴回弹的影响。在早喷和晚喷条件下，初始活塞位置较高，大部分喷射的燃油撞击在活塞上。随着喷射压力的增加，由于喷射的快速发展，发生壁面碰撞的喷射时间提前。