Investigation of Droplet Motion and Grouping

喷雾剂用于各种各样的技术系统。喷雾的使用范围从燃料的燃烧到表面的目标涂层。这些喷雾的效率取决于液滴的动态行为，包括形成液滴组的趋势。这种分组趋势对整个喷雾的蒸发和运动行为具有显著影响，例如也对涂覆过程期间液滴的分布具有显著影响。液滴的分组在能量和传输系统、涂层或药物递送（例如，在吸入系统中）中具有分支。因此，对所发生的现象的更好理解使得能够控制基团形成过程，从而提高系统的效率，例如关于排放控制、材料节省，表面质量或药物分布。第二个资助期的申请继续了第一个资助期的工作，并在此基础上进行了扩展。理论上，数值上和实验上。整个分组过程可以分为三个连续的阶段。首先，开始形成组，并且液滴开始彼此接近，随后是实际的接近过程，其最终以液滴凝结结束。基团的形成可以例如通过外部流场或通过液滴形成过程来引发。研究的一个目的是研究可能的成组过程，以确定影响和初始化形成过程的方法，从而具体地促进或避免液滴的凝结。在该项目的第一个资助期内，已经通过实验、数值和分析研究了一个和多个液滴流中液滴的接近过程。在我们正在申请的第二个资助期内，研究将扩展到包括液滴形状、液滴振荡、声场效应和液滴蒸发对液滴运动和聚集行为的影响的详细研究。申请合作伙伴BGU、Technion和ITLR拥有不同的实验、数值和分析方法，当它们结合在一起时，允许详细研究液滴分组的所有关键子过程。有些方法是重叠的，因此可以直接比较和验证结果。与项目第一阶段一样，计划在合作伙伴之间开展非常密集的合作。

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.