液滴高速撞击固体表面的飞溅动力学研究

液滴撞击固体表面产生的飞溅现象包括快速飞溅和日冕飞溅两种类型，对航空航天和工农业生产等诸多领域具有重要影响，但其动力学过程、形成机理和影响因素等问题仍未得到充分理解。为弥补现有研究的不足，本项目拟采用实验研究、数值模拟和理论分析相结合的方式，开展如下系统性工作：首先，阐明液滴飞溅过程中液滴整体、前端液膜和次级液滴的形貌演化规律以及气、液两相流场的时空变化规律，将跨时间和空间尺度的过程联系起来，完整刻画液滴飞溅过程的动力学特征；其次，深入剖析前端液膜的形貌特征及其受到的气动力，探明快速飞溅和日冕飞溅中前端液膜的不同失稳机制并据此建立两种飞溅的理论预测模型；最后，厘清固体表面润湿性、液体粘度和表面张力、气体压强、密度和粘度等因素对两种飞溅的阈值及次级液滴特征的影响规律。本项目的开展，有望促进液滴撞击动力学的发展，并为实际应用中预测和控制液滴飞溅提供理论依据，具有重要的学术价值和广阔的应用前景。

Droplet splash induced by its high-speed impingement upon solid surfaces can be categorized into two types, namely prompt splash and corona splash, which have significant influence on the development of aerospace technique and various agricultural and industrial applications. However, the dynamic process, the underlying mechanisms and the affecting factors are still not well understood. In this project, experimental, numerical and theoretical approaches will be combined to carry out the following investigations. Firstly, geometric evolutions of bulk droplets, liquid lamella and secondary droplets, as well as the velocity and pressure filed of the liquid and gas phases will be investigated, in order to link processes spanning over different temporal and spacial scales and describe the complete dynamic features of the splash processes. Secondly, geometric features of the liquid lamella and the aerodynamic forces acting on it will be analyzed, in order to better understand the different instability mechanisms of the liquid lamella during prompt and corona splash, based on which theoretical prediction models of the two splashes will be developed. Finally, the dependence of the thresholds of two splashes and the features of secondary droplets on different properties, such as the wettability of the solid surfaces, the viscosity and surface tension of the liquid, as well as the pressure, density and viscosity of the gas, will be clarified. It is expected that the results of this project may help improve the development of the droplet impact dynamics and provide theoretical support for the prediction and control of droplet splashing in various applications, being important from both academic and industrial point of views.