Numerical Simulation Of Energy Dissipation Characteristics Of Cover Plate In Gate Chamber Under The Condition Of Super Water Transfer Power

In recent years,the number of ship locks which are under construction or are planned to be built in navigable rivers in China has increased rapidly,and the need for shipping development has stimulated the development of lock towards ultra-high water head and advancing on large scale.Therefore,the design of water conveyance system,which are the key technology of ship lock construction,are faced with more severe challenges.When the water head and the scale of the lock reach a large number of levels,it is required that the water body filled into the lock chamber within a certain time should have huge energy and the corresponding water conveyance power need to be increased exponentially.In order to find out the characteristics and mechanism of the energy dissipation on the roof of the gate chamber under the condition of super water transfer power,and the key control factors affecting the flow field and water surface fluctuation of the gate chamber,a type of water conveyance system with a graded energy dissipation structure is used to simulate the energy dissipation of cover panels of various structures by Fluent numerical calculation software in this paper.The main results are as follows:1.The turbulence model adopted in the numerical simulation is the Reynolds stress model.And the result is highly consistent with that of theoretical solution.Therefore,the model established could be regarded as reliable.2.The energy dissipation process of the first three kinds of graded energy dissipation structures can be divided into two stages: one is the energy dissipation of the wall of the energy dissipation chamber by the side support hole,the other is the energy dissipation of the jet cover plate at the top branch hole.The energy dissipation process of concave cover plate structure with energy dissipation sill can be divided into three stages,the first two stages are the same as the former,and the third stage is that the cover plate is mixed in the semi-open energy dissipation chamber after the discharge of the cover plate and the energy dissipation is collided.From the turbulent energy distribution,it can be seen that most of the energy dissipation in each working condition is from the first stage.3.The distribution of turbulent energy in the energy dissipation chamber is as follows: the maximum turbulent energy is located near the wall of the lateral branch hole,and gradually diverges around it,and the transverse divergence region is about 6 m.The transverse turbulent energy distribution in the cover cavity is mainly concentrated in the middle and weakens gradually on both sides.In the energy dissipation chamber,the side wall of the brake wall and the surface of the cover plate,the water collides with it,and friction dissipates some energy.4.The change of the height of the energy dissipation chamber with the convex cover plate type is compared and it is found that the change of the height has little effect on the energy dissipation effect.The main reasons are as follows: under the same flow rate,the main corridor,the side branch hole and the energy dissipation chamber form a closed space,the flow rate determines the flow velocity at the top branch hole,and the flow field entering the area of the gate chamber under the same type of working condition is basically the same.5.For the double top branch hole structure,when the distance between the two top branch holes reaches a certain order of magnitude,two streams of water flow will be mixed,and in the cavity of the cover plate,the space between the two top branch holes will form two small swirls of mixing.When the net height of the cover cavity is about 7 times of the width of the branch hole and the net spacing of the branch hole reaches 4 times of the width of the branch hole,a relatively stable vortex can be formed.6.In this paper,the index of energy dissipation effect is the residual specific energy of the bottom plane of the ship when the lowest water level is designed in the lock chamber,so as to judge the influence on the berthing of the ship.In the case of several structural types presented in this paper,the residual specific energy of concave cover plate with energy dissipation sill is lower and the effect is better.The residual specific energy of this structure is about 30% lower than that of non-cover plate under various working conditions,and 20% lower than that of convex cover.