Jet flipping phenomenon below sluice gate

• Main Author: Peng, Li.
• Other Authors: Lim Siow Yong
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/40068
• Institution: Nanyang Technological University

Erosion of sediment bed would lead to hydraulic structure failure. The investigation of scouring can effectively predict structure failure and control the damage to the environment or mankind. In this project, an effort is made to understand the scour caused by jet issuing from submerged sluice gate. Jet flipping was a very particular phenomenon during the scour process. The sluice gate was fixed with an opening of 9mm. The tailwater depths were always kept high enough to create submerged flow. Green Sand of a mean size of 0.78mm was filled into the flume as the cohesionless sediment bed. The sluice gate was fixed just above the right edge of the apron, indicating no apron length in the experiments, which gave the worst scenario in reality. The experiments were conducted in two series. Series A focused on the influence of the flow rate on the scour process while Series B investigated how the tailwater depth worked on the scour process. The study verified that jet flipping could be observed within the experimental period only for certain hydraulic conditions. Simply speaking, the term “jet flipping” referred to the cyclic process of jet flipping from the bed (digging phase with calm water surface) and to the free surface (filling phase with “boiling” water surface) throughout the experiment. On the other hand, no flipping could be observed if some factors didn‟t satisfy the conditions. The occurrence of the jet flipping deserves to be investigated for better prediction of erosion of the riverbed downstream of the structure.