Change Pattern of Velocity of Intermediate Channel with Unsteady Flow Resulted by Ship Lock Discharge

The velocity evolution process caused by the unsteady flow of lock discharge, where the key problem is the relationships between the hydraulic factors in the restricted middle navigable channel and the transformation of unsteady flow and the corresponding scales are investigated. Based on the restricted middle navigable channel of the Baise navigation project, the relationship between the unsteady flow discharge process of lock and the velocity evolution process in the restricted middle channel is studied through systematic experiments, and the conclusion is drawn as follows. The main reason caused the flow fluctuation is attributed to insufficient energy dissipation, the rapid increase of discharge during the lock discharge process, and the limited boundaries. By reducing the peak value of the time-discharge curve, the maximum velocity and maximum inverse velocity decrease in the upper restricted middle navigable channel. In the long restricted middle navigable channel, due to the energy consumption, the velocity fluctuation in the downstream is much smaller than that in the upstream, which still exists after the flow pattern reaches a steady state. This study can provide a theoretical basis for the middle channel layout design.