A vertical pipe inlet-and-outlet is a common inlet-and-outlet type for controlling water flow at both ends of a pumped storage power station waterway system. It is a passage of bidirectional flows that undergoes two 90° turns (horizontal-vertical-horizontal) within a short distance. In such an inlet-an-outlet

flow direction changes drastically and its hydraulic conditions are complicated. For the design and construction of pumped storage power plants

it is of great significance to conduct an in-depth study of its hydraulic characteristics and to optimize its structure and shape. This paper first discusses the application background of the vertical pipe inlet-and-outlet and the characteristics of its channel shape

and examines the problems with its hydraulic characteristics. Then

we present a summary on the recent progress in the research on this device

the distribution of flow velocity in its trash rack section

the vortices and its head loss

etc. Finally

we sum up the research methods for its hydraulic characteristics

and suggest certain directions to focus on in the future research.