Abstract
In this study, we experimentally observed the high-speed water droplet impact on acrylic surfaces in a vacuum chamber with a high-speed photography, in order to clarify the effects of both the ambient gas pressure around the droplet and the impact velocity. The results show that the splash does not occur under the reduced ambient gas pressure even when the impact velocity becomes much higher than in the conventional experiments. This result agreed with our previous experiments of ethanol droplet impacts. Furthermore, we observed that generation processes of splash in low ambient and atmospheric gas pressures are different.
