Analysis of Pressure Differences and Water Transverse Movement in a Partial-Flip Bucket

Abstract

The partial-flip bucket is successfully applied to a spillway outlet design with an approximately 50 m/s flow velocity in Jinping-I Dam in Sichuan, China. The specific design of a part-flipped area on a floor results in a long and narrow jet of high-velocity flow released from the flip bucket. The reductions in the pressure on the side wall and the flow discharge impact on the riverbed downstream confirm that the energy dissipation issue is effectively solved in high-head dams. However, detailed information on the transverse movement of flow in the partial-flip bucket is lacking. The present study uses numerical simulations to analyze interior flow structures, including pressure and transverse velocity distributions. The effect of transverse pressure differences on the water flow contraction is investigated. Transverse pressure differences between the sidewall and interior water are accompanied by sudden pressure release in the unflipped area; differences are more pronounced around the incipient cross sections of the unflipped area and decrease as the water flows over the downstream flip bucket. This pressure difference results in transverse velocities, leading to the transverse contraction of the water flow. Compared to the stalling conditions of the traditional deflector flip bucket, the partial-flip bucket can extend the practical applicability of flow discharge operations.