Ribeiro, DanielaPanão, MiguelBarata, Jorge M MSilva, A. R. R.2020-08-312020-08-312020-01-05http://hdl.handle.net/10400.6/10403Within the wide possibilities for the resultant outcome of a single droplet impinging upon a liquid film, there is an unstudied phenomenon that seems to be underestimated or forgotten in time. The formation of a bubble by the crown sheet closure at the top after crown splash is the focus of this paper. The phenomenon was deeply studied as well as its occurrence, main features, and physical significance. It is important to understand completely the phenomenon to asses if it should be encouraged or avoided inside the combustion chamber of an IC engine, since it has higher production of secondary atomization due to the larger lifetime, and on the other hand, the bubble bursting increase the production of airborne particles that could affectthe pollutant emissions. Several impacts conditions were tested and it was found three different types of bubble formation depending on the jets formed at the closure point. The event was observed both from below and from the side, enhancing the knowledge about the droplet-film impact itself. The main features were studied including, the bubbling height and diameter, and the propagation velocity of the first perturbation imposed on the liquid film.engDroplet ImpactThin Liquid LayersBubble FormationExperimentalSecondary atomisationBiofuelsconference object10.2514/6.2020-1577