Compensation of the first reverse peak of the hydrodynamic force during filling of the lock chamber with a head supply system

This paper presents research aimed at studying the hydraulics of the filling process of navigation locks with a head supply system feeding from beneath flat lifting and lowering gates. In particular, the problem of compensating the first reverse peak of the hydrodynamic force by varying the area of the filling opening is considered. The change in the filling opening area was analyzed both for cases of constant size and for cases of reduction. In a theoretical experiment, the timing and intensity of the change in the filling opening area were synchronized with the wave propagation speed in the lock chamber. The first release wave formed at the start of filling must be compensated by a second wave, which is forcibly created by reducing the cross-sectional area of the filling opening, followed by its increase. The parameters of the second compensating wave were determined so that its interaction with the first release wave eliminates the first peak of the reverse hydrodynamic force. The mode of changing the filling opening area was also studied. To achieve this, theoretical methods based on solving unsteady water motion equations were used, allowing determination of free surface fluctuations in the lock chamber, including at the initial filling stage. The results show, for various vessel displacements, the dependence of hydrodynamic force magnitude on the modes of filling opening area change and on the related increment of water flow. The findings can help create safe locking conditions for both current and future unmanned vessels.