Our aim is to understand the air entrainment into a suction pipe inside a suction sump in the vertical-wet-pit-pump configuration. This suction-sump flow accompanying the air entrainment often appears in various industrial and environmental problems, however is usually complicated owing to both their unsteadiness with poor periodicity and their fully-three-dimensionality. In the present study, we investigate the influences of governing parameters upon the occurrence-time ratio γ of the air entrainment using a bubble sensor.
