Abstract In the current study, a novel three-dimensional (3D) measurement technique is established using a high-speed stereoscopic shadowgraph system, which is applied to investigate the 3D splashing dynamics of silicone oil dropping on liquid films quantitatively. Both crown-type splashing and crown wall bottom breakdown splashing morphologies are involved for measurement and comparison. Based on the shadowgraph images, the secondary droplets diameter, number and mass fraction are determined. The three-dimensional (3D) coordinates of the secondary droplets during the splashing processes are reconstructed and tracked, based on which the 3D trajectories, velocities, ejecting angles and kinetic energy are calculated and analysed. It is found that the secondary droplets in crown bottom breakdown cases have a larger mass fraction and kinetic energy than that in crown-type splashing cases. The measurement indicates that the radial velocity increases with the decreasing of film thickness, while the vertical velocity does not vary too much. Significant disparities between two-dimensional (2D) and three-dimensional (3D) velocity magnitudes as well as kinetic energy have been identified, which indicate that accurate time-resolved 3D measurements are of great importance for quantitative investigation of splashing phenomena and the high-speed stereoscopic shadowgraph system has been proved to be able to play a role.

中文翻译：

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立体阴影图系统的三维液滴飞溅动态测量

摘要 在目前的研究中，建立了一种新的三维（3D）测量技术，该技术使用高速立体阴影图系统，用于定量研究硅油滴在液膜上的 3D 飞溅动力学。冠型飞溅和冠壁底部击穿飞溅形态均涉及测量和比较。基于阴影图像，确定二次液滴的直径、数量和质量分数。飞溅过程中二次液滴的三维 (3D) 坐标被重建和跟踪，在此基础上计算和分析 3D 轨迹、速度、喷射角和动能。发现冠底击穿情况下二次液滴的质量分数和动能大于冠型飞溅情况。测量表明，径向速度随着薄膜厚度的减小而增加，而垂直速度变化不大。二维 (2D) 和三维 (3D) 速度大小以及动能之间存在显着差异，这表明准确的时间分辨 3D 测量对于飞溅现象的定量研究和高速度立体阴影图系统已被证明能够发挥作用。而垂直速度变化不大。二维 (2D) 和三维 (3D) 速度大小以及动能之间存在显着差异，这表明准确的时间分辨 3D 测量对于飞溅现象的定量研究和高速度立体阴影图系统已被证明能够发挥作用。而垂直速度变化不大。二维 (2D) 和三维 (3D) 速度大小以及动能之间存在显着差异，这表明准确的时间分辨 3D 测量对于飞溅现象的定量研究和高速度立体阴影图系统已被证明能够发挥作用。