Research on Technological Improvements with Regard to Navigable Flow Conditions at the Entrance Area of Ship Lock

Navigable flow conditions in the entrance area of the channel approaching a lock are usually complicated because of the specificity of the boundary conditions. At the downstream entrance of a lock, an oblique flow and circumfluence is always formed due to the sudden expansion of the boundary. When passing through the entrance area, the ship is in danger of rolling and yawing under the influence of the adverse flow pattern, which can cause accidents. Therefore, to ensure safe ship navigation, improvements to the navigable flow conditions in the entrance area need considerable research and attention. Considering the relevant literature, we find that current navigation-improvement technologies intended for installation at lock entrances mainly involve the construction of diversion structures to control diffusion flow, including perforated diversion dikes, floating dikes, diversion piers, and diversion vanes with pile foundations. In this study, the engineering characteristics, technical mechanisms, and applicable conditions of the above diversion structures are addressed by means of integrated physical model test and remote control self-propelled ship model test. The results are as follows: First, perforated diversion dikes and floating dikes can mitigate the influence of oblique flow on the navigability of ships by restricting the diffusion of surface water. However, if the oblique flow velocity in the entrance area is high, the flow pattern will become turbulent because of the perforated structure at the bottom of the entrance area, generating whirlpools, boil-vortex flows, and other adverse flow patterns that adversely affect the navigability of ships. Secondly, diversion piers can reduce the backflow intensity and the flow declination angle around the lock entrance by diverting the diffusion flow, but the effect is limited to weakening the oblique flow intensity. Third, diversion vanes with pile foundations can weaken the strong oblique flow around the entrance by combining both, blocking and diverting the diffusion flow. The same can be applied across a relatively wide range of projects.