An Approach To The Limit Value Of Navigable Flow Conditions At The Entrance Area Of Ship Lock In Curved Reach

The entrance area of Ship Lock has an important role in the hydro-junction,which influences whether the ship can safely enter and exit the channel.So,according to relevant industry standards in China dam site in general to be elected in the straight and stable river,lock entrance is generally located in the straight reach in order to ensure the safety of ship lockage,it also limited the navigable flow condition of the entrance area of ship lock,the transverse velocity limit value is one of the most important conditions to determine whether the ship can navigate safely in the pilot crossing area.But for mountain rivers,the entrance area of ship lock can only be arranged in the curved reach because of the terrain,information on sorting out such key projects is found,although the lateral velocity exceeds the flow limit value at some areas of the entrance area located on the curved reach of the river,the ship model meets the requirements of navigation parameters at certain allowable speed,as of Dayuandu Hydropower Station,Feilaixia Hydro-junction,Naji Hydropower Station etc.,and the actual project operation data show that the ship is safe to navigate.When the transverse velocity of the section in the curved reach exceeds the standard limit value,the safety of navigation identified is different result between the flow condition test and the ship model test.In this regard,this paper will establish the model of the curved generalizational tank,using the research method combining the flow condition test and the ship model navigation test explores that,the different entrance area(upstream and downstream)is located in the river bend in different positions(convex and concave),whether the transverse flow velocity exceeds the standard limit value,the ship can also be safe to navigate;if this phenomenon exists,it is necessary to analyze the reason that the ship can navigate safely at this time.The main research results through the model test in the curved generalizational tank of this paper are as follows:(1)Different entrance area(upstream and downstream)located in the river bend in different positions(convex and concave),when the transverse flow velocity in the condition of more than codelimits ship model in some permissible under the safety of navigation,there are differences between the results of flow condition test and model test,and analysing the ship at this time can cause the safety of navigation is related with the speed of a ship.(2)By using the momentum theory,when the bend radius of the bend and the scale of the ship model are fixed,considering the influence of the upstream and downstream factors of the ship model and so on,using a large number of experiments and using statistical methods,a numerical model of the maximum heading angle and the ratio of the transverse velocity to the ship's model speed is established by using the linear regression method,and the regression equation of the maximum heading angle is obtained.(3)The influencing factors of rudder effect of ship model are analyzed in the course of turning around the bend,when the scale of the ship model are fixed,considering the influence of bending radius,up and down of ship model and so on,using a large number of experiments and using statistical methods,a numerical model of the maximum rudder angle and the ratio of the transverse velocity to the ship's model speed is established by using the linear regression method,and the regression equation of the maximum rudder angle of the ship model at the bend is obtained.(4)Deducing the minimum critical speed of the ship model passing through the enterance area.(5)Two ways of judging whether the ship can pass through the entrance area safely is proposed:the method of determining the navigational parameter and the minimum value of safe navigation speed.