| After the impoundment of the Three Gorges Reservoir at 175 m,the channel conditions in the reservoir area have been greatly improved.However,the large scale vortices in the Fupingback Reach of Guangyangba in the fluctuating backwater area during the fluctuation period are obstructing navigation flow patterns,which have a great impact on the safety and navigation efficiency of passing vessels.The causes of vortex formation in Fupingbei reach are complicated and it is difficult to control them thoroughly.Moreover,this reach belongs to the protected area,and large-scale waterway regulation works are restricted.Therefore,it is of positive significance to find out the navigation obstruction characteristics of large-scale vortices and optimize the layout of waterways and shipping routes to improve the navigation safety and efficiency of ships.Based on the physical model test in the Fuping Back Reach of the upper reaches of the Yangtze River,combined with the navigation test of the small scale automatic ship model,this paper studies the attitude response relationship between the vortexes and ship navigation under different intensity,and puts forward the criterion of the safe distance of the normal uplink when the ship encounters vortexes in the Fuping Back Reach.The main achievements are as follows:(1)The characteristics of large-scale eddy movement in the Fupingbeihe reach are analyzed.By observing the shape of the vortex under the four-level design flow,the characteristics of its development frequency and movement path were obtained.Based on the principle of optical flow method,the flow field on the surface of the vortex in the Fupingbei reach was measured to obtain the parameters of its movement speed,which provided support for the quantitative analysis between the vortex and ships.(2)The moving target detection method suitable for ship model test is optimized.The principle of combining with the inverse perspective projection transformation test shooting video image correction,and to reduce the light tracer factors such as interference,is put forward based on the principle of computer vision is ship motion position extraction method,according to the coordinate transformation to get location information in the cartesian coordinate system and draw ship motion trajectories,analysis for ship sailing velocity,sailing drift Angle and line parameters such as Angle of deflection.(3)A two-dimensional mathematical model of the upward deflection movement of ships in the large scale vortex area of the Fuping Beihe section is proposed.Considering the motion characteristics of the vortex and the relative position of the ship’s center of mass and the center of the vortex core,a theoretical force model of ship’s motion in two-dimensional plane is proposed based on the slender strip theory.At the same time,combined with the boundary of Fuping Beihe reach and the influence factors of hydraulic conditions,the causes of ship’s upward deflection in this reach are obtained.(4)Determine the judgment of normal uplink safe distance for ships in Fupingbei reach.By carrying out 100 groups of ship model sea trials and extracting track lines,considering the strength of vortex structure comprehensively and combining with the statistical real-time response parameters of ship attitude,the ship motion model is adopted to calculate the numerical variation of ship motion force.Based on dimendimenless analysis,1st Opt software was used to carry out multiple regression analysis,and the attitude response equation of a 3000-ton ship under the influence of multiple parameters when encountering vortices at a speed of 5m/s was proposed to determine the safe sailing Angle of the ship,and to obtain the safe distance when encountering vortices in the Fuping Back River section. |
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