Investigation of Droplet Motion and Grouping

喷雾剂广泛应用于各种技术系统。喷雾的使用范围从燃料的燃烧到表面的目标涂层。这些喷雾的效率是由液滴的动态行为决定的，包括形成液滴群的趋势。这种分组趋势对整个喷雾的蒸发和运动行为有显著的影响，例如对涂层过程中液滴的分布也有显著的影响。液滴的分组在能源和运输系统、涂层或药物输送（例如吸入系统）中具有分支。因此，更好地了解所发生的现象，可以控制基团形成过程，从而提高系统的效率，例如在排放控制、材料节约、表面质量或药物分配方面。第二个资助期的申请延续了第一个资助期的工作，并在此基础上进行了扩展。发生的个别详细现象进行了理论、数值和实验研究。整个分组过程可以用三个连续的阶段来描述。首先，开始形成基团，液滴开始相互靠近，然后是实际的接近过程，最后以液滴凝固结束。例如，可以通过外部流场或液滴形成过程来启动群的形成。研究的目的之一是研究团形成的可能过程，确定影响和初始化形成过程的方法，从而具体促进或避免液滴的凝聚。在项目的第一个资助期，已经对液滴在一个和几个液滴蒸汽中的接近过程进行了实验、数值和分析研究。在我们申请的第二个资助期内，我们将扩大研究范围，包括详细研究液滴形状、液滴振荡、声场和液滴蒸发对液滴运动和分组行为的影响。应用合作伙伴BGU， Technion和ITLR拥有不同的实验，数值和分析方法，当它们结合起来时，可以详细研究液滴分组的所有关键子过程。有些方法重叠，因此可以直接比较和验证结果。与项目的第一阶段一样，计划在合作伙伴之间进行非常密切的合作。

Sprays are used in a wide variety of technical systems. The use of sprays ranges from the combustion of fuels to the targeted coating of surfaces. The efficiency of these sprays is determined by the dynamic behavior of the droplets, which includes the tendency to form droplet groups. This grouping tendency has a significant effect on the evaporation and movement behavior of the entire spray, e.g. also on the distribution of the droplets during coating processes. The grouping of droplets has ramifications in energy and transport systems, in coating or in drug delivery (e.g. in inhalation systems). A better understanding of the phenomena that occur, thus, enables the group formation process to be controlled and thus to increase the efficiency of the systems, for example with regard to emission control, material savings, surface quality or drug distribution.This application for the second funding period continues the work done in the first funding period and expands on it. The individual detailed phenomena that occur are investigated theoretically, numerically and experimentally. The entire process of grouping can be described by three successive phases. First, the formation of groups is initiated and the droplets begin to approach each other, followed by the actual approach process, which finally ends with droplet coagulation. The formation of groups can be initiated, for example by the external flow field or by the droplet formation process. One aim of the investigations is to study possible processes of group formation, to identify methods for influencing and initializing the formation process and thus to specifically promote or avoid the coagulation of droplets. In the first funding period of the project, the approach processes of droplets within one and several droplet steams were already investigated experimentally, numerically and analytically. In the second funding period, which we are applying for, the investigations are to be extended to include a detailed investigation of the influences of droplet shape, droplet oscillations, the effect of an acoustic field and the drop evaporation on the droplet movement and the grouping behavior.The applying partners, BGU, Technion and ITLR, have different experimental, numerical and analytical methods at their disposal, which, when combined, allow to study all crucial sub-processes of droplet grouping in detail. Some methods overlap, thus allowing direct comparison and validation of the results. As in the first phase of the project, a very intensive cooperation between the partners is planned.