Free drop-particle collisions occurring in air are experimentally produced by combining a stream of drops and a stream of particles, which results from the selective and ultra-fast hardening of another regular drop stream. The set-up offers the possibility to accurately vary the drop and particle diameter, the collision eccentricity and the relative drop-particle velocity. First observations obtained with drop Weber numbers ranging from 30 to 300, drop Reynolds number between 390 and 4600, and with typical equilibrium contact angle of 70° evidence the existence of full deposition, separation and bouncing events. For off-center separation, a liquid ligament forms between the particle and the outlying drop cap that fragments due to excessive stretching, a phenomenon similar to what can be observed for drop-drop collisions. In contrast, for head-on collisions and intermediate inertia, a lamella first forms, whose constrained recoil leads to liquid protuberance(s) that eventually pinch(es)-off. These outcomes can be distinguished using a bi-dimensional regime map built on the impact parameter and the drop Weber number. Despite remarkable similarities with binary drop collisions, important differences are observed especially for low and moderate eccentricities.

中文翻译：

---

研究液滴粒子碰撞的新颖实验方法

空气中发生的自由液滴-粒子碰撞是通过将液滴流和粒子流组合而实验产生的，这是由另一个规则液滴流的选择性和超快速硬化产生的。该装置提供了精确改变液滴和颗粒直径、碰撞偏心率和相对液滴颗粒速度的可能性。首次观察到的液滴韦伯数在 30 到 300 之间，液滴雷诺数在 390 到 4600 之间，并且典型的平衡接触角为 70°，这证明了完全沉积、分离和弹跳事件的存在。对于偏心分离，在颗粒和外围滴帽之间形成液体韧带，该液体韧带由于过度拉伸而破裂，这种现象类似于在液滴碰撞中观察到的现象。相反，对于正面碰撞和中等惯性，首先形成薄片，其受约束的反冲导致液体突起最终被夹断。这些结果可以使用基于影响参数和下降韦伯数构建的二维状态图来区分。尽管与二元液滴碰撞有显着的相似之处，但仍观察到重要的差异，特别是对于低偏心率和中等偏心率。