Energy Dissipation Characteristics Of A Combined Structure Consisted Of A Single Open Ditch And A Sill In A Shiplock Filling/Emptying System

The hydraulic structure of a single open ditch designed for the in-Chamber Longitudinal Culvert System is the common type of intermediate water head in lock engineering,however,with the increase of water head and scale of ship lock,the navigation requirements will naturally increase.The single open ditch energy dissipation can not meet the navigation requirements.Therefore,domestic researchers put forward the composite hydraulic structure with single open ditch and stilling sill to enhance the energy dissipation effect of open ditch.Meanwhile,existing research results has yet to single open ditch and a sill study carried out in cooperation with energy dissipation system.In this thesis,the local three-dimensional mathematical model is established by using a single open ditch designed for the in-Chamber Longitudinal Culvert System.Based on the CFD simulation method based on fluent,the energy dissipation characteristics of single open ditch cooperative a sill with different layout the side ports arrangement height,the height of the sill and the distance from the sill to side ports are deeply studied.The main research work and conclusions are as follows:(1)Compared computing grid sensitivity analysis and numerical simulation results with physical model results,when the minimum mesh size is 0.2m,the corresponding grid number is 1.85×10~5,using standard turbulence model,they are generally in good agreement;(2)According to the analysis of the residual specific energy(Ept)and the uniformity of flow velocity distribution(m)on the characteristic horizontal section of the lock chamber,the effect of the arrangement height of the branch hole,the height of the energy dissipation threshold and the distance between the energy dissipation threshold and the branch hole on the energy dissipation effect is clarified Law of influence.When the height of the energy-saving threshold is mainly changed,when the height of the side branch hole h0/h≤0.3,when the distance s/B of the energy-saving threshold from the branch hole is in the range of 0.4～0.6,the values of Ept and m The height of the energy dissipation threshold gradually increases,and the energy dissipation effect gradually deteriorates;when 0.6<s/B≤0.8,generally,the values of Ept and m gradually decrease as the height of the energy dissipation threshold increases,and the energy dissipation effect gradually becomes better.;In the case of 0.3<h0/h≤0.45,when 0.4≤s/B≤0.6,the value of Ept and m tends to decrease first and then increase as the height of the energy dissipation threshold increases,and the energy dissipation effect first becomes better.Deterioration;when 0.6<s/B≤0.8,the values of Ept and m gradually increase with the increase of the height of the dysfunction threshold,but the increase is limited;(3)Results showed that the height of the sill and the distance from the sill to side ports located in the culvert should be fixed at 0≤h2’/h1’≤1,and 0.6≤s/B≤0.8,respectively;In addition,the side ports arrangement height should be fixed at0≤h0/h≤0.15;(4)This thesis reveals a single open ditch and a sill in the filling/emptying of the energy dissipation mechanism,especially in the presence of the side ports arrangement height of jet flow,sill and open ditch of collaborative energy dissipation mechanism.