Author(s): Biruk Belay; Mario Oertel
Linked Author(s): Mario Oertel
Keywords: No Keywords
Abstract: Piano key weirs are types of nonlinear weirs characterized by their advantages for implementation in space-constrained environments, such as spillway structures over dams or head control weirs over horizontal channels. Despite the previous extensive research on discharge efficiency and energy dissipation aspects, knowledge of their downstream air entrainment characteristics has not been sufficiently addressed and it is essential in enhancing design practices. Thus, this experimental study evaluated the basic air-water flow characteristics downstream of an A-type trapezoidal piano key weir under the influence of variable tailwater. The results revealed that the overall air entrainment and air concentrations were notably affected by the changes in downstream tailwater levels under a constant inflow. Simultaneously, the bubble count rate profiles also depicted significant dependence on the downstream condition. In such cases, an increase in tailwater generally reduces the air concentration and the bubble count rates throughout the downstream region.
Year: 2026