Observation and classification of droplet/liquid film collision behavior between different liquids

The purpose of this study was to elucidate collisions between droplets and a liquid film, where the liquid film and the droplets are composed of different liquids. Understanding this phenomenon is important to improve the environmental performance of internal combustion engines. The collision behavior of different liquids under the simplified experimental system is discussed on the basis of experimental results. The impingement of a single droplet on a liquid film was observed using a high-speed video camera. Another observation was carried out to distinguish whether the secondary droplets by splash were derived from fuel or liquid film. The different splash phenomena from the same liquid collision experiment were observed. The collision behavior of different liquids was classified into four categories. The characteristics of the collision behavior and underlying mechanisms were discussed and elucidated. An empirical formula that represents the phenomena was derived.