Abstract The understanding of fuel spray impingement phenomenon and its impact of film formation on wall are significant for engine related applications, such as emission reduction and lubrication improvement, etc. However, the impingement phenomenon of the airborne droplets in the wall jet moving parallel to the wall has not been fully understood yet, especially for the fact that negligible amount of fuel film is formed underneath the wall jet. In this experimental research, various laser diagnostic techniques, including laser-induced fluorescence, Mie scattering, phase Doppler interferometry, and particle imaging velocimetry were utilized to capture both macroscopic and microscopic behavior of the spray impingement process. It was found that droplets in the spray with a high tangential velocity may be governed by the lift force induced by the boundary layer near the plate, gliding away without impinging the wall and forming wall film. Based on the observations, a modified impingement criterion is proposed to incorporate such gliding effects to improve the current understanding of droplet-wall interactions.

中文翻译：

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壁面喷射液滴对喷射冲击燃料成膜的影响实验研究

摘要 了解燃料喷雾撞击现象及其对壁面成膜的影响对于发动机相关应用，如减排和润滑改善等具有重要意义。壁面尚未完全了解，特别是因为壁面射流下方形成的燃料膜量可忽略不计。在这项实验研究中，各种激光诊断技术，包括激光诱导荧光、米氏散射、相位多普勒干涉仪和粒子成像测速仪，被用来捕捉喷雾冲击过程的宏观和微观行为。发现具有高切向速度的喷雾中的液滴可能受板附近边界层引起的升力控制，在不撞击壁并形成壁膜的情况下滑行。根据观察结果，提出了一种改进的撞击标准，以结合这种滑动效应，以提高目前对液滴-壁相互作用的理解。