Three-dimensional flow observation on the air entrainment into a vertical-wet-pit pump

The authors consider the air entrainment into a suction pipe which is vertically inserted down into a suction sump across a mean free-water surface. This configuration is often referred to as the "vertical wet-pit pump," and has many practical advantages in construction, maintenance and operation. Most of the flows appearing in various industrial and environmental problems like the present suction- sump flow become often complicated owing to both of their unsteadiness with poor periodicity and their fully-three-dimensionality. In order to understand the complicated flow inside a suction sump in the vertical-wet-pit-pump configuration, the authors experimentally observe the flow using the three-dimensional particle tracking velocimetry (3D-PTV) technique, which includes more unknown factors in accuracy and reliability than other established measuring techniques. So, the authors examine the simultaneous measurement by the 3D-PTV with another velocimetry the ultrasonic velocity profiler. As a result, under the suitable condition with high accuracy, the authors have revealed the complicated flow.