Flow Characteristics Of Multiple Face-to-face Turbulent Jets For Shiplock Filling And Emptying Systems

Ship lock is one of the main types of navigation structures.It is widely used because of its relatively mature technology and stable operation.The jet flow with the opposite direction is a common hydraulic problem in the ship lock conveyance system.The turbulent structure and mixing characteristics are directly related to the water delivery efficiency and the energy dissipation effect.However,the characteristic of the jet is not only the characteristics of the multiple jet,but also the flow characteristics such as collision and cross flow under complex boundary conditions.The hydrodynamic characteristics of the jet are very complicated.At present,the research on similar problems at home and abroad is not comprehensive and systematic,and the flow phenomena and characteristics are still lack of theoretical analysis.This paper is based on the National Natural Science Fund Project " Energy dissipation mechanism and flow structures of multiple face-to-face turbulent jets in filling and emptying system of shiplocks",and research flow characteristics of multiple face-to-face turbulent jets in shiplock filling and emptying systems,using the computational fluid dynamics software FLUENT and RNG double equation turbulence model(simulation of free surface by VOF method).The establishment of three-dimensional computations of a single hole turbulent jet and multiple face-to-face turbulent jet of different jet velocity,different hole spacing and different momentum flux are studied more than 14 working conditions.The main research results are as follows:(1)The formula of velocity distribution of arbitrary section and the maximum velocity attenuation formula of radial attenuation zone are proposed.(2)In the single-hole jet center plane,the velocity half-value width increases linearly along the jet direction,and the linear growth rate in the nucleus of the jet is independent of the initial velocity of the perforation,in the fully developed area of jet flow,the velocity of perforation flow cross section is smaller,the velocity half value is wide,and the increase rate is bigger,until 1v ≤0.775 m/s,then the speed half-value width growth rate almost becomes constant(k=0.105).(3)The concept of turbulent energy per unit area k is proposed,by analyzing the influence of the dislocation pitch on the turbulent energy per unit area,it is concluded that the jet mixing is most intense when s/B=1/20;the mixing intensity between the two jets is second When s/B=3/20 and 1/5;the mixing intensity between the two jets is weakest when s/B=1/10 and 1/4.(4)Through the establishment of face-to-face turbulent jet energy dissipation calculation formula,the effect of energy dissipation is better,when the s/B=1/20,3/20 and 1/5;the effect of energy dissipation is commonly,when s/B=1/10;the effect of energy dissipation is poor,when s/B=1/4;and the energy dissipation effect vary with the momentum flux ratio decreases.(5)Compared to the turbulent jet mixing characteristics and energy dissipation effect,put forward to the two hole dislocation spacing should be 1/5 chamber width(s/B=1/5).