| As a special restrictive channel,the middle channel has a much smaller section coefficient than the natural channel,the channelized channel and the lock approach channel because of the limited channel scale.It is mostly set between the cascade lock and the ship lift.Due to its particularity and limited application scope,there is no special standard for intermediate channels at home and abroad.Most of them conduct special model tests,three-dimensional numerical simulation or real ship test research for specific problems,and put forward navigation standards for a certain project.With the gradual increase of the construction of high dam navigation water conservancy projects in China,the middle channel,as a flexible dispatching operation channel,is gradually widely used.Intermediate channel design,the middle channel navigation standard is closely related to the speed of the ship navigation,if you want to design a reasonable and economic middle channel section,determine the reasonable intermediate channel navigation standard,must understand the ship in the middle channel,such as ship navigation resistance and channel section coefficient,the relationship between the sinking and section coefficient and the middle channel ship wave rule,etc.This paper adopts the method of combining three-dimensional flow-solid coupling numerical simulation and theoretical analysis,systematically studies the relationship between the ship resistance of the 3000 t class and the latest 10000 t class direct ship in the three Gorges Reservoir area,and proposes the two methods of ship resistance in the middle channel.The following conclusions were drawn from the study:(1)Intermediate channel width on ship navigation resistance: the same channel depth(shallow water 1.5 times the draft)and ship speed,3000 t and 10000 t class ship resistance increases with the channel width,the channel width 1.5 times the width,2m/s navigation resistance,the navigation resistance secondary power curve increases,speed <2 m/s,navigation resistance approximately linear growth,channel width 2.5times the width,ship resistance is no longer obvious,and close to open waters,a linear increase.(2)The influence of the middle channel water depth on the ship navigation resistance: under the same channel width and ship speed,the navigation resistance of the ships of 3000 t and 10000 t increases with the decrease of the water depth.When the water depth is 1.5 times the draft of the ships,the navigation resistance of the ships increases sharply due to the obvious shallow water effect.When the water depth is 2.6times the ship draft,the shallow water effect is no longer obvious,and the ship navigation resistance has tended to the deep water channel.(3)According to the study of the influence of the middle channel width and water depth on the ship navigation resistance,the influence of the section coefficient on the navigation resistance of ships is that the larger the section coefficient,the smaller the resistance.When the section coefficient is 2.5,the piston effect and shallow water effect will appear,and the navigation resistance of the ship increases sharply;when the section coefficient is 4.0,the change of the ship navigation resistance will be flat.When the section coefficient is between the two,the ship navigation resistance shows the increasing trend of the secondary power curve.(4)Based on the sample data of the ship navigation resistance under the different section coefficient,the critical speed of the critical speed of the ship under the different section speed of the ship,which can provide a reference for the intermediate channel navigation standard.(5)Based on the numerical simulation data of ship navigation friction resistance and residual resistance samples in different section coefficient,the friction resistance terms and residual resistance terms in the existing calculation formula of ship navigation resistance in Yu Zhongqi restricted channel are corrected.It mainly includes the width influence coefficient is introduced in the friction resistance term,the width influence coefficient is corrected in the residual resistance term,and the ship type influence coefficient is introduced.Finally,the formula suitable for the navigation resistance calculation of intermediate channel ships is put forward. |
