Artificial Control Against Unstable Flow in Submerged Jump Below Single or Multiple Gates

Youichi Yasuda¹, and Shintarou Narazaki²

1. College of Science and Technology, Department of Civil Engineering, Nihon University, Japan

2. Graduate School of Science and Technology, Department of Civil Engineering, Nihon University, Japan

Abstract: For the formation of submerged hydraulic jump with a large submergence, a high velocity flow below a sluice gate is located near the bottom. When the main flow lifts to the water surface from the channel bottom, in some cases, the main flow is periodically deflected. In this case, it might be difficult for swimming fishes to migrate upstream through the hydraulic structure, even if the fish passage is installed at the downstream of the structure. Therefore, there is a need to the periodically deflected flow must be changed to a stabilized flow. In this study, the installation of baffle blocks with asymmetrical length at the downstream of sluice gates was proposed in order to disappear a periodically deflected flow in submerged hydraulic jump. The experiments yield that the periodically deflected flow can be disappeared. The artificially controlled flow has been confirmed by time averaged velocity and the velocity with time series.