A method for determining channel width under supercritical cross flow conditions

Abstract

The application discloses a kind of determination methods of waterway width under the condition of super-standard cross flow, comprising the following steps: 1) collecting waterway basic data;2) according to waterway basic data, construct plane two-dimensional water flow mathematical model;3) based on ship motion equation, establish ship maneuvering motion mathematical model;4) based on the ship maneuvering motion mathematical model, under the action of different waterway grade and different super-standard cross flow, the ship navigation posture is simulated, and the navigation motion parameter of representative ship under the action of different waterway grade and different super-standard cross flow is obtained;5) according to the navigation motion parameter of representative ship under the action of super-standard cross flow, the quantitative relationship between super-standard cross flow and waterway width widening value under different waterway grade conditions is obtained by simulation;The application can solve the technical problems that the navigation flow condition judgment index of waterway under the action of super-standard cross flow in the prior art is relatively single, which can easily lead to inaccurate design or judgment result of ship navigation parameter.

Description

Technical Field

[0001] This invention relates to the field of ship navigation, and specifically to a method for determining the width of a waterway under conditions of excessive cross current. Background Technology

[0002] my country's inland waterway development has a long history. Since ancient times, inland waterway transportation has been one of the important means of economic development and cultural exchange. In recent years, the development of my country's inland waterways has accelerated, achieving remarkable results. On the one hand, my country has increased its support for inland waterway construction and transportation services, strengthening the construction of inland waterway infrastructure and improving water transport services. On the other hand, inland waterway shipping companies are also continuously strengthening their capabilities in technological innovation, informatization, energy conservation and emission reduction, improving the operational efficiency and service quality of inland waterway transportation. Currently, the development of inland waterways faces new opportunities and challenges.

[0003] my country's natural waterways contain numerous confluences of main streams and tributaries, as well as complex navigation channels. The Yangtze River, with its 70,000-kilometer navigable length, is known as China's "golden waterway," its main stream, tributaries, and lakes interconnected to form China's largest water transport network. Furthermore, the Pearl River, composed of the Xijiang, Beijiang, and Dongjiang rivers, also has a wide distribution of confluences. These confluences typically feature significant drops in elevation, narrow and winding channels, and rapid currents, posing challenges to safe navigation. Additionally, the mountainous waterways of the upper reaches of the Yangtze and its tributaries often have numerous shoals and rapids, complex channel topography, many rocky ridges and protrusions along the banks, and significant riverbed undulations, resulting in numerous complex navigation channels. Therefore, the water flow conditions at the confluences of main streams and tributaries, and within complex channels, are complex, turbulent, and involve significant crossflows, requiring a greater channel width for safe navigation than in straight waterways.

[0004] However, the current standard for navigable flow conditions at the confluence of tributaries and complex sections of waterways still borrows from the standard for navigable flow conditions at the entrance of the lock approach channel in the "Inland Waterway Navigation Standard". This standard stipulates that the transverse flow velocity in the waterway must not exceed 0.3 m / s to ensure safe navigation. This evaluation method has a relatively simple indicator. To achieve this standard, the usual practice is to increase the waterway size through waterway improvement to improve navigable flow conditions, reduce transverse flow, and ensure that the transverse flow in the waterway does not exceed 0.3 m / s. This approach has the following shortcomings: (1) Under normal circumstances, the amount of waterway improvement work required to achieve a transverse flow of 0.3 m / s is large and the cost is high; (2) There is a lack of quantitative relationship between the transverse flow exceeding the standard (>0.3 m / s) and the required waterway width.

[0005] The aforementioned shortcomings can easily lead to inaccurate design or judgment results of navigation parameters for ships under navigable current conditions at the confluence of main and tributary streams and in complex waterways. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the width of a waterway under conditions of excessive crossflow, in order to solve the technical problem that the existing technology has relatively simple indicators for judging the navigation flow conditions of waterways under the action of excessive crossflow, which does not take into account the influence of factors such as waterway grade and ship maneuverability on navigation, and is prone to inaccurate design or judgment results of ship navigation parameters under the conditions of navigable flow conditions at the confluence of main and tributary streams and complex waterways.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for determining the width of a waterway under conditions of excessive crossflow, comprising the following steps:

[0009] S1. Collect basic waterway data;

[0010] S2. Based on the basic data of the waterway, construct a two-dimensional planar mathematical model of water flow;

[0011] S3. Establish a mathematical model of ship maneuvering motion based on ship motion equations;

[0012] S4. Based on the mathematical model of ship maneuvering motion, the ship's navigation attitude is simulated under different waterway grades and different cross currents, and the navigation motion parameters of the ship under the cross currents are obtained under different waterway grades.

[0013] S5. Based on the navigation motion parameters of representative ships under the action of excessive cross current, the quantitative relationship between excessive cross current and the channel width widening value under different channel grades is obtained through simulation.

[0014] Preferably, in step S2, the planar two-dimensional water flow mathematical model is constructed using the average water depth finite element method, and the parameters of the waterway at different time periods are simulated, specifically including the following steps:

[0015] S2.1, Set the boundary conditions for the model;

[0016] S2.2. Based on the fundamental equations of the finite element method of average water depth, a set of nonlinear equations is obtained by numerical discretization of the fundamental equations.

[0017] S2.3 Solve the above nonlinear equations to obtain the parameter values ​​of the waterway at different time periods.

[0018] As a preferred option, the parameters of the waterway at different times include water level, water depth, current velocity, and current direction.

[0019] Preferably, in step S2.1, the boundary conditions of the two-dimensional planar flow mathematical model include the inlet boundary, the outlet boundary, and the bank boundary.

[0020] Preferably, in step S4, the expressions for the ship's position and related parameters at any given time, representing the ship's navigation motion parameters under the influence of excessive crossflow, are as follows:

[0021]

[0022] In the formula, the subscript i in the parameters represents time i, the subscript i+1 represents time i+1, Δt is the time increment, and x i Let x be the position of the ship in the x direction at time i. i+1 Let y be the position of the ship in the x direction at time i+1. i The position of the ship in the y direction at time i, y i+1 Let v be the position of the ship in the y-direction at time i+1. x v is the relative velocity between the ship and the water flow in the x-direction. y The relative velocity between the ship and the water flow in the y-direction is given by r; the angular velocity of the ship turning at the bow is given by u. x u is the velocity of the origin of the moving coordinate system in the x-direction. y V is the velocity of the origin of the moving coordinate system in the y-direction. F ψ represents the absolute velocity of the water flow. F ψ represents the direction of water flow; ψ represents the bow angle of the ship.

[0023] Preferably, in step S5, based on the navigation motion parameters representing the ship under the influence of the excessive crossflow, a quantitative relationship between the excessive crossflow and the channel width widening value under different channel grades is obtained through simulation, including the following steps:

[0024] S5.1 Based on the relationship between the ship's drift speed and the cross current, the ship's motion state under different cross current conditions is simulated using a mathematical model of ship maneuvering motion, and then the relationship between the ship's drift speed and the cross current in the channel is obtained.

[0025] S5.2 Analyze the relationship between cross current and navigation drift angle to obtain the curve showing the change of ship navigation drift angle with cross current speed in the channel;

[0026] S5.3 Based on the relationship between the ship's drift speed and the cross current in the above-mentioned channel and the correspondence between the cross current and the navigation drift angle, simulate the required channel range limit under the condition of excessive cross current and the required channel widening value under the condition of excessive cross current.

[0027] Preferably, in step S5.1, under the conditions of ship speed Vs = 0.5 m / s on the opposite shore and rudder angle of 25°, the combined relationship between the lateral drift velocity and the crossflow velocity in the channel is as follows:

[0028] V f =1.08V y -0.08;

[0029] In the formula: V f V is the drift velocity, in m / s; y The velocity is the crossflow velocity, in m / s.

[0030] Preferably, in step S5.3, under the conditions of a water flow velocity of 3.0 m / s, a ship's speed on the opposite shore of 0.5 m / s, and a rudder angle of 25°, the relationship between the required channel range limit under the condition of exceeding the standard crossflow is as follows:

[0031]

[0032] In the formula: L d B is the safe length of the crossflow region, in meters. d V is the width of the uplink trackband, in meters. s V is the ship's speed on the opposite shore, in m / s; y The velocity is the crossflow velocity, in m / s.

[0033] Preferably, in step S5.3, the required channel widening value under the excessive crossflow conditions is in the range of 0.3 to 188.2 m; wherein, the ship navigates in a uniform crossflow area and is parallel to the centerline of the channel, the crossflow velocity ranges from 0.35 m / s to 0.6 m / s, the length of the crossflow area ranges from 10 to 80 m, and the ship's speed on the opposite bank is 0.5 m / s.

[0034] Preferably, the required channel widening value under the excessive crossflow conditions can be applied to Class I to V waterways, wherein:

[0035] For Class I waterways, the vessel tonnage is 3000t and the width is 100m. The representative vessel dimensions are: overall length × beam × design draft.

[0036] = 95 × 16.2 × 3.2 m, corresponding to a crossflow exceeding the standard and a channel widening value range of 0.5 to 150.8 m;

[0037] For Class II waterways, the vessel tonnage is 2000t and the width is 75m. The representative vessel dimensions are: overall length × beam × design draft.

[0038] = 90 × 14.8 × 2.6 m, corresponding to a crossflow exceeding the standard and a channel widening range of 0.3 to 164.9 m;

[0039] For Class III waterways, vessels with a tonnage of 1000t and a beam of 60m are permitted. The representative vessel dimensions are: overall length × beam × design draft.

[0040] = 85 × 10.8 × 2.0 m, corresponding to the range of crossflow and channel widening values ​​exceeding the standard, which is 3.5 to 174.1 m;

[0041] For Class IV waterways, the tonnage of vessels is 500t and the width is 50m. The representative vessel dimensions are: overall length × beam × design draft.

[0042] = 67.5 × 10.8 × 1.6 m, corresponding to a range of 2.3 to 182.6 m for the crossflow and channel widening values ​​exceeding the standard;

[0043] For Class V waterways, the vessel tonnage is 300t and the width is 40m. The representative vessel dimensions are: overall length × beam × design draft.

[0044] =55×8.6×1.3m, corresponding to the range of crossflow and channel widening values ​​exceeding the standard is 1.6~188.2m.

[0045] The present invention has the following beneficial effects: The method for determining the channel width under the condition of excessive crossflow disclosed in this invention constructs a mathematical model of ship maneuvering motion and conducts a series of numerical simulations of ship motion under the action of excessive crossflow. It obtains the navigation state of representative ships in Class I to V inland waterways in the uniform crossflow region. Then, it comprehensively analyzes the navigation parameters of ships under the action of crossflow by combining water flow conditions and simulation results, proposes expressions for the ship drift velocity under different crossflow conditions, as well as the safe range of excessive crossflow, and gives the range of main channel dimensions required for safe navigation of ships under different channel grades and different crossflow sizes. It also establishes a quantitative relationship between the excessive crossflow and the channel width widening value under different channel grades. This provides a quantitative design basis and methodological reference for the design of cross-current channels exceeding the standard, ensuring safe navigation of ships under the influence of cross-currents. It solves the technical problem that the existing technology has relatively simple indicators for judging the navigation flow conditions of channels under the action of cross-currents exceeding the standard, and does not consider the impact of factors such as channel grade and ship maneuverability on navigation. This can easily lead to inaccurate design or judgment results of ship navigation parameters under the navigation flow conditions of tributary confluence and complex sections. Attached Figure Description

[0046] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0047] Figure 1 This is a flowchart of the method of the present invention.

[0048] Figure 2 The trajectory of a 3000t cargo ship under crossflow is shown in the present invention.

[0049] Figure 3 The trajectory of a 2000t cargo ship under crossflow is shown in the present invention.

[0050] Figure 4 The trajectory of a 1000t cargo ship under crossflow is shown in the present invention.

[0051] Figure 5 The trajectory of a 500t cargo ship under crossflow is shown in the present invention.

[0052] Figure 6 The trajectory of a 300t cargo ship under crossflow is shown in the present invention.

[0053] Figure 7 This is a diagram showing the relationship between the drift velocity and the crossflow velocity in each level of the waterway according to the present invention (VS = 0.5 m / s).

[0054] Figure 8 The relationship between the ship's drift angle and cross-current velocity (VS = 0.5 m / s) is given in this invention.

[0055] Figure 9 The present invention defines the maximum crossflow length that a ship can withstand for safe navigation under conditions exceeding the standard crossflow.

[0056] Figure 10 The safety value of the crossflow region length in the Class I waterway of this invention and The relationship (VS = 0.5 m / s).

[0057] Figure 11 The safety value of the crossflow region length in the Class II waterway of this invention and The relationship (VS = 0.5 m / s).

[0058] Figure 12 The safety value of the crossflow region length in the Class III waterway of this invention and The relationship (VS = 0.5 m / s).

[0059] Figure 13 The safety value of the crossflow region length in the Class IV waterway of this invention and The relationship (VS = 0.5 m / s).

[0060] Figure 14 The safety value of the crossflow region length in Class V waterways of this invention and The relationship (VS = 0.5 m / s).

[0061] Figure 15 This invention provides a comparison of ship drift under different crossflow conditions (Class I waterway).

[0062] Figure 16 This invention relates to the relationship between the length of the crossflow range exceeding the standard and the lateral drift distance (Class I waterway).

[0063] Figure 17 This invention relates to the relationship between excessive crossflow and channel widening value (Class I waterway).

[0064] Figure 18 This invention provides a comparison of ship drift under different crossflow conditions (Class II waterway).

[0065] Figure 19 This invention relates to the relationship between the crossflow range exceeding the standard and the cross-drift distance (Class II waterway).

[0066] Figure 20 This invention relates to the relationship between excessive crossflow and channel widening value (Class II waterway).

[0067] Figure 21 This invention compares the lateral drift of ships under different crossflow conditions in the waterway (Class III waterway).

[0068] Figure 22 This invention relates to the relationship between the crossflow range exceeding the standard and the drift distance (Class III waterway).

[0069] Figure 23 This invention relates to the relationship between excessive crossflow and channel widening value (Class III waterway).

[0070] Figure 24 This invention compares the lateral drift of ships under different crossflow conditions in the waterway (Class IV waterway).

[0071] Figure 25 This invention relates to the relationship between the crossflow range exceeding the standard and the cross-drift distance (Class IV waterway).

[0072] Figure 26 This invention relates to the relationship between excessive crossflow and channel widening value (Class IV waterway).

[0073] Figure 27 This invention provides a comparison of ship drift under different crossflow conditions (Class V waterway).

[0074] Figure 28 This invention relates to the relationship between the crossflow range exceeding the standard and the cross-drift distance (Class V waterway).

[0075] Figure 29 This invention relates to the relationship between excessive crossflow and channel widening value (Class V waterway). Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0077] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. In addition, the terms "horizontal," "vertical," etc., do not indicate that the component is required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0078] This invention can be applied to the design, improvement or reconstruction of waterways when ships are navigating. It solves the technical problem that the existing technology has a relatively simple index for judging the navigation flow conditions of waterways under the action of excessive crossflow. It does not take into account the influence of factors such as waterway grade and ship maneuverability on navigation, which easily leads to inaccurate design or judgment results of ship navigation parameters under the navigation flow conditions of the confluence of main and tributary streams and complex waterways.

[0079] This invention discloses a method for determining the width of a waterway under conditions of excessive crossflow, comprising the following steps:

[0080] S1. Collect basic waterway data;

[0081] S2. Based on the basic data of the waterway, construct a two-dimensional planar mathematical model of water flow;

[0082] S3. Establish a mathematical model of ship maneuvering motion based on ship motion equations;

[0083] S4. Based on the mathematical model of ship maneuvering motion, the ship's navigation attitude is simulated under different waterway grades and different cross currents, and the navigation motion parameters of the ship under the cross currents are obtained under different waterway grades.

[0084] S5. Based on the navigation motion parameters of representative ships under the action of excessive cross current, the quantitative relationship between excessive cross current and the channel width widening value under different channel grades is obtained through simulation.

[0085] Specifically, the "Inland Waterway Navigation Standard" (GB50139-2014) makes principled provisions on navigation flow conditions, requiring that the transverse flow velocity not exceed the limit of 0.3 m / s. This invention defines the transverse flow velocity exceeding the 0.3 m / s limit as the excessive transverse flow velocity.

[0086] Specifically, in step S1, the basic channel data includes, but is not limited to, characteristic parameters of typical tributary confluences, existing research results on tributary confluence navigation flow conditions, and criteria for determining navigable flow conditions of the main channel under tributary confluence conditions. Among these, the characteristic parameters of typical tributary confluences lay the foundation for constructing the two-dimensional planar flow mathematical model and the ship maneuvering motion mathematical model in steps S2 and S3.

[0087] Specifically, the force analysis of the ship's navigation in this scheme is as follows:

[0088] (1) Equation of the force exerted by the transverse water flow on the hull

[0089] When a ship navigates in a uniform crossflow without adjusting the rudder angle, the ship will experience its own thrust F and water resistance R. x and the lateral thrust R caused by crossflow y The force equations for the lateral water flow acting on the hull are as follows:

[0090]

[0091] In equation (1): ρ is the density of water; L s T represents the ship's length; C represents the ship's draft; q V is the flow pressure coefficient; y This refers to the lateral velocity of the water flow.

[0092] set up Then equation (1) becomes:

[0093]

[0094] (2) Equation of torque caused by steering angle

[0095] When a ship sails along a predetermined route in a waterway, the ship's hull is subjected to its own thrust F and water resistance R.x and the lateral thrust R caused by crossflow y When the crossflow is uniformly distributed, the lateral thrust R y The force acting on the ship's center of gravity causes the ship to drift laterally. At this point, the rudder angle needs to be adjusted to ensure the ship's position is parallel to the course. The rudder force P caused by rudder input can be decomposed into a force P parallel to the course. x and P perpendicular to the flight path y Vertical component P y The generated torque M P This causes the ship to drift sideways in the opposite direction.

[0096] The equation for the torque caused by the control rudder angle is as follows:

[0097] M P =l P ·Pcosδ (3)

[0098] In equation (3): P is the rudder force; l P l is the length between the point of application of the rudder force and the ship's center of gravity. P ≈0.5L s δ represents the rudder angle.

[0099] The rudder force can be determined by the following formula:

[0100]

[0101] In equation (4): ρ is the density of water, C q Where A is the pressure coefficient, A is the area of ​​the rudder, and V is the pressure coefficient. r The speed of the rudder blade relative to the water.

[0102] Therefore, the force generated by manipulating the rudder angle is related to the size of the rudder angle and the speed of the rudder blade. When a ship passes through a crossflow area, it needs to maneuver the rudder angle to resist the lateral drift caused by the crossflow. The greater the crossflow speed, the greater the rudder angle and the greater the speed of the rudder blade that need to be manipulated.

[0103] (3) Velocity vector equations during the ship's up and down movements

[0104] When a ship navigates in a crossflow region, the crossflow velocity has a complex relationship with the navigation parameters. The velocity vector equations for the ship during its up and down flows are shown below:

[0105] V y =V w sinθ (5)

[0106] V y '=V w sin(θ+α) (6)

[0107] In equations (5) and (6): V wV is the combined velocity of the water flow. y V is the transverse flow velocity. y ' is the lateral velocity of the ship, θ is the angle of the water flow, and α is the heading angle.

[0108] From equations (4) and (5), it can be seen that when the crossflow velocity in the channel is large, the ship sails upstream, lifting its bow against the current to pass through the crossflow zone. x '≤V x This can reduce the force of the river on the ship; when the ship is traveling downstream through a crossflow area, it still needs to raise its bow and use a relatively high speed to pass through, although at this time V x >V x The ship is subjected to a large cross-current force, but the ship can resist the influence of the cross-current force to a certain extent by virtue of its own large thrust.

[0109] Preferably, in step S2, the planar two-dimensional water flow mathematical model is constructed using the average water depth finite element method, and the parameters of the waterway at different time periods are simulated, specifically including the following steps:

[0110] S2.1, Set the boundary conditions for the model;

[0111] S2.2. Based on the fundamental equations of the finite element method of average water depth, a set of nonlinear equations is obtained by numerical discretization of the fundamental equations.

[0112] S2.3 Solve the above nonlinear equations to obtain the parameter values ​​of the waterway at different time periods.

[0113] As a preferred option, the parameters of the waterway at different times include water level, water depth, current velocity, and current direction.

[0114] Specifically, the fundamental equations used in the average water depth finite element method are:

[0115] (1) Continuity equation

[0116]

[0117] (2) Momentum equation

[0118] x-direction:

[0119]

[0120] y direction:

[0121]

[0122] In equations (7), (8) and (9), t is time; n is the roughness coefficient; u is the flow velocity in the x direction; v is the flow velocity in the y direction; h is the water depth; a is the water level; g is the gravitational acceleration; and ε is the turbulent viscosity coefficient (ε = αu * h, where the value of α ranges from 3 to 5).

[0123] Preferably, in step S2.1, the boundary conditions of the two-dimensional planar flow mathematical model include the inlet boundary, the outlet boundary, and the bank boundary, and the three boundary conditions are as follows:

[0124] Import boundary: r = r B (t), s=s B (t), where r B For the main flow process line, s B For tributary flow process curves;

[0125] Export boundary: h = h B (t), where h B This is the water level hydrograph;

[0126] The riverbank boundary is the boundary between the water surface and the riverbank. Because the riverbank is impermeable, the normal flow velocity v is... n Defined as zero, its tangential velocity v is determined by the Chezy-Manning formula. t r, s and v n v t The conversion formula is as follows:

[0127]

[0128] In equation (10), v n v is the upward flow velocity at the bank boundary. t Let be the flow velocity tangentially along the bank boundary, and r and s be the inlet boundary functions.

[0129]

[0130] In equation (11), θ is the angle between the normal flow velocity and the X direction.

[0131] For a given research domain, the initial conditions are set as follows:

[0132] h(x,y,t)| t＝0 =h0(x,y) (12)

[0133] r(x,y,t)| t＝0 =r0(x,y) (13)

[0134] s(x,y,t)| t＝0 =s0(x,y) (14)

[0135] In equations (12), (13) and (14), h0, r0 and s0 are the water level, main stream flow component and tributary flow component at the initial time, respectively.

[0136] Specifically, in step S2.2, the numerical discretization of the fundamental equations includes discretization in the time dimension and discretization in the spatial dimension, wherein:

[0137] The time dimension is discretized using the finite difference method, which discretizes the equation into a system of nonlinear algebraic equations, and then solves it using the Newton-Raphson iterative method.

[0138] The spatial dimension is discretized using the finite element method, with triangular six-node isoparametric elements used as nodes within the discretized region to ensure computational accuracy and stability. The discretized equations are then discretized using the Galerkin weighted residual method to obtain a system of nonlinear algebraic equations. Specifically, the discretization and solution of the fundamental equations are existing techniques and will not be elaborated upon here.

[0139] Specifically, the numerical simulation of two-dimensional planar water flow using the aforementioned two-dimensional planar water flow mathematical model is implemented using Fortran programming.

[0140] Specifically, the two-dimensional planar flow mathematical model used in this scheme has been verified, and the calculated values ​​of the model are basically consistent with the measured values. This indicates that the two-dimensional flow mathematical model and numerical calculation method are reasonable, can effectively simulate the river flow pattern, and provide basic hydrodynamic parameters for the numerical simulation of ship maneuvering motion.

[0141] Specifically, in step S3, the mathematical model of ship maneuvering motion is constructed based on the MMG model;

[0142] The MMG (Maneuvering Motion Generator) model is a decomposed model, a ship control system proposed by the Japanese MMG team. This model decomposes the forces and moments acting on the ship into forces and moments acting on the hull, propeller, and rudder respectively, providing a more refined description of the ship's motion characteristics. The MMG model comprises three main components: the ship's control mechanisms, environmental conditions, and the ship's dynamics model. Regarding the control mechanisms, the model considers the dynamic response of the control system and the crew's maneuvering behavior; regarding environmental conditions, the model considers the effects of ocean dynamics, wind, waves, and currents on the ship; and regarding the dynamics model, the model considers factors such as the ship's inertia, drag, and propulsion during motion. The mathematical modeling method and principle of the MMG model decomposes the hydrodynamic forces and moments acting on the ship into hydrodynamic forces and moments acting on the bare hull, open-water propeller, and open-water rudder, as well as the interference forces and moments between them, and provides calculation methods for each force and moment. In ship model experiments, the differential physical meaning of the MMG model is very clear, which can well explain the relationship between the ship model and the actual ship, and it has been widely used in motion modeling of various ships.

[0143] Specifically, in step S3, the ship's motion simulated by the mathematical model of ship maneuvering motion is the ship's three-degree-of-freedom motion in a plane within the rectangular coordinate system x0O0y0, and the ship's motion equation is:

[0144]

[0145] In equation (15), m represents the added mass and the added moment of inertia, where I z Let v be the moment of inertia of the ship about the z-axis. x v is the relative velocity between the ship and the water flow in the x-direction. y y is the relative velocity between the ship and the water flow in the y-direction; r is the ship's bow turning angular velocity; X is the resultant force acting on the ship's x-axis; Y is the resultant force acting on the ship's y-axis; N is the resultant moment about the ship's center of gravity perpendicular to the axis; u x u is the velocity of the origin of the moving coordinate system in the x-direction. y V is the velocity of the origin of the moving coordinate system in the y-direction. F ψ represents the absolute velocity of the water flow. F ψ represents the direction of water flow; ψ represents the bow angle of the ship.

[0146] Solving equation (15) yields the expressions for the ship's position and related parameters at any given time in the mathematical model of ship maneuvering motion under the influence of excessive crossflow, as shown below:

[0147]

[0148] In equation (16), the subscript i in the parameters represents time i, the subscript i+1 represents time i+1, Δt is the time increment, and x i Let x be the position of the ship in the x direction at time i. i+1 Let y be the position of the ship in the x direction at time i+1. i The position of the ship in the y direction at time i, y i+1 Let v be the position of the ship in the y-direction at time i+1. x v is the relative velocity between the ship and the water flow in the x-direction. y The relative velocity between the ship and the water flow in the y-direction is given by r; the angular velocity of the ship turning at the bow is given by u. x u is the velocity of the origin of the moving coordinate system in the x-direction. y V is the velocity of the origin of the moving coordinate system in the y-direction. F ψ represents the absolute velocity of the water flow. F ψ represents the direction of water flow; ψ represents the bow angle of the ship.

[0149] Specifically, this scheme selected 3000t, 2000t, 1000t, 500t, and 300t cargo ships in inland waterways as representative ship types to verify the mathematical model of ship maneuvering motion. The simulation results show that the straight-line performance of each representative ship type is stable in still water, and the speed, trajectory, and direction of navigation during straight-line navigation are reasonable. Under still water conditions, when the rudder angle reaches 25°, the turning diameter of each ship type is approximately twice its length, and the steady turning diameter is approximately 1.5 to 3.5 times the ship length. This indicates that the straight-line propulsion performance and still-water turning performance of the five types of inland waterway cargo ships calculated from the above ship maneuvering motion are stable and can be applied to various studies of numerical simulation of ship maneuvering motion.

[0150] In addition, this scheme also conducted simulation tests on the mathematical model of ship maneuvering motion. Using numerical simulation technology of ship maneuvering, turning tests and Z-shaped tests were carried out on cargo ships of 3000t, 2000t, 1000t, 500t and 300t in inland waterway transportation. The simulation results showed the maneuvering performance of various types of ships under different working conditions, which can serve as the basis for subsequent simulation calculation of the channel width widening value.

[0151] Specifically, the representative vessel refers to the vessel dimensions corresponding to inland waterways of grades I to V as specified in the "Inland Waterway Navigation Standards" (GB50139-2014).

[0152] Specifically, in step S4, the different waterway grades refer to the Class I to Class V waterways specified in the "Inland Waterway Navigation Standards" (GB50139-2014).

[0153] Specifically, in step S4, the ship maneuvering motion mathematical model conducted a series of numerical simulations on the ship motion under the action of excessive crossflow, and obtained the navigation state of representative ships in the uniform crossflow region in inland waterways of Class I to V. Among them, the navigation motion parameters of representative ships include, but are not limited to, the navigation attitude and rudder angle, drift angle, onshore speed, on-water speed, channel dimensions, ship type, length of crossflow region, and other navigation parameters of representative ships in different uniform crossflow regions.

[0154] Preferably, in step S5, based on the navigation motion parameters representing the ship under the influence of the excessive crossflow, a quantitative relationship between the excessive crossflow and the channel width widening value under different channel grades is obtained through simulation, including the following steps:

[0155] S5.1 Based on the relationship between the ship's drift speed and the cross current, the ship's motion state under different cross current conditions is simulated using a mathematical model of ship maneuvering motion, and then the relationship between the ship's drift speed and the cross current in the channel is obtained.

[0156] S5.2 Analyze the relationship between cross current and navigation drift angle to obtain the curve showing the change of ship navigation drift angle with cross current speed in the channel;

[0157] S5.3 Based on the relationship between the ship's drift speed and the cross current in the above-mentioned channel and the correspondence between the cross current and the navigation drift angle, simulate the required channel range limit under the condition of excessive cross current and the required channel widening value under the condition of excessive cross current.

[0158] Specifically, in step S5.1, the relationship between the ship's lateral drift speed and the cross current is as follows: When a ship is navigating in a channel, it will drift laterally due to the influence of the cross current and the rudder force used to control the rudder angle. The speed of the ship's lateral drift is called the lateral drift speed, usually denoted by V. f The drift speed is one of the important indicators for evaluating the impact of crosscurrents on ship navigation, and it can reflect the degree of lateral deviation of the ship.

[0159] The drift speed can be determined by the following formula:

[0160]

[0161] In equation (17): V s The speed of the ship on the opposite shore; This is the bow angle of the ship.

[0162] Specifically, in step S5.2, the curve showing the relationship between the ship's drift angle and the crossflow velocity is related to the subsequent channel width value. The greater the crossflow velocity, the greater the drift angle, the more obvious the ship's yaw, the wider the channel required, and the greater the corresponding widening value.

[0163] Preferably, in step S5.3, the required channel widening value under the excessive crossflow conditions is in the range of 0.3 to 188.2 m; wherein, the ship navigates in a uniform crossflow area and is parallel to the centerline of the channel, the crossflow velocity ranges from 0.35 m / s to 0.6 m / s, the length of the crossflow area ranges from 10 to 80 m, and the ship's speed on the opposite bank is 0.5 m / s.

[0164] Specifically, the range of crosscurrents exceeding the standard and the channel widening value for Class I waterways is 0.5–150.8m; for Class II waterways, it is 0.3–164.9m; for Class III waterways, it is 3.5–174.1m; for Class IV waterways, it is 2.3–182.6m; and for Class V waterways, it is 1.6–188.2m.

[0165] The method for determining channel width under excessive crossflow conditions disclosed in this invention has the following technical advantages: In the prior art, the indicators for judging the navigable flow conditions of channels under excessive crossflow are relatively simple, and do not consider the influence of factors such as channel grade and ship maneuverability on navigation. The method for determining channel width under excessive crossflow conditions disclosed in this invention constructs a mathematical model of ship maneuvering motion and conducts a series of numerical simulations of ship motion under excessive crossflow. It obtains the navigation state of representative ships in inland waterways of grades I to V in a uniform crossflow region. Then, combining the flow conditions and simulation results, it comprehensively analyzes the ship navigation parameters under crossflow, proposes expressions for ship drift speed under different crossflow conditions, and defines the safe range of excessive crossflow. It also gives the range of main channel dimensions required for safe navigation of ships under different channel grades and different crossflow sizes, including the increase in channel width compared to traditional channel dimensions. A quantitative relationship between excessive crossflow and channel width increase is established for different channel grades. It provides a quantitative design basis and methodological reference for the design of cross-current channels that exceed the standard, ensuring that ships can navigate safely under the influence of cross currents.

[0166] To further illustrate the method for determining channel width under conditions of excessive crossflow, the present invention discloses the following embodiments:

[0167] This embodiment applies the above method to the Yangtze River main channel. First, on-site measurement data of the Changshou Shantuo section of the Yangtze River main channel are collected. Then, based on the established two-dimensional planar flow mathematical model, hydrodynamic numerical simulation of the engineering section is performed, and the simulation results are compared and verified with the measured water surface line, flow velocity, and flow direction distribution of the engineering section. Based on the vessel dimensions of inland waterways of Class I to V, numerical simulations of the basic maneuvering motions of representative vessels are carried out to verify the maneuvering performance of each representative vessel in still water straight navigation, turning, etc.

[0168] Specifically, the representative vessels refer to the vessel dimensions corresponding to inland waterways of grades I to V as specified in the "Inland Waterway Navigation Standards" (GB50139-2014), as shown in Table 1 below.

[0169] Table 1 Dimensions of Natural and Canalized River Channels

[0170]

[0171] Furthermore, when ships navigate close to a quay, the water flow changes due to the presence of the quay, creating eddies and turbulence. These changes generate pressure differences, subjecting the ship to lateral forces and thus affecting its navigation and stability. Therefore, the quay effect can impact ship navigation when navigating close to a quay. To mitigate the effects of the quay effect, ships typically maintain a sufficient margin of safety when navigating waterways, ensuring safe passage.

[0172] Specifically, the formula for calculating the safe distance is:

[0173] d=k(B Fd +B Fu (18)

[0174] B Fd =B Sd +L d sinβ (19)

[0175] B Fu =B Su +L u sinβ (20)

[0176] In equations (18), (19), and (20): d is the safety distance; B Fd B is the width of the downstream vessel track. Fu B is the width of the track of an upstream vessel. Sd B is the width of the vessel going downstream; Su For the width of the vessel traveling upstream; L d L is the length of the downstream vessel. u β is the length of the vessel going downstream; β is the vessel's drift angle; k is the safety distance coefficient, which can generally be 0.67 to 0.8 for cargo ships.

[0177] Generally, a ship's maximum rudder angle can reach 35°, which allows the ship to have the maximum turning moment. When a ship is sailing in a cross-current area, in addition to the effect of the cross-current, it is also affected by the combined effects of wind, shore wall effect, and ship-to-ship effect. The ship needs to consume some rudder force to overcome the influence of the other external forces.

[0178] Therefore, in this embodiment, the maximum rudder angle for safe navigation of the ship is in the range of 20 to 25°.

[0179] Therefore, in order to ensure the feasibility of the safety indicators, in this embodiment, the maximum rudder angle for safe navigation of the ship is preferably 25°.

[0180] Specifically, the parameters of inland waterways and the dimensions of representative vessels can determine the safe distance d for each level of waterway, as shown in Table 2.

[0181] Table 2 Determination of Safety Distances for Each Level of Waterway

[0182]

[0183] Next, a simulation test of the ship's maneuvering motion under cross-current limit conditions will be conducted.

[0184] It should be noted that the water flow velocity in inland waterways is relatively high, but usually does not exceed 2-3 m / s, and the lateral flow velocity does not exceed 0.3 m / s. When ships pass through rapids, they must maintain a certain speed on the opposite bank to successfully navigate the rapids; the speed on the opposite bank is generally not less than 0.5 m / s.

[0185] First, the ship's maneuverability is examined when the crossflow is 0.3 m / s. Assuming the ship is traveling upstream (i.e., on the beach), fully loaded, and temporarily disregarding the effects of the shore wall and wind, the crossflow is taken as 0.3 m / s, the current velocity is taken as 3.0 m / s under unfavorable conditions, the ship's speed on the opposite shore is 0.5 m / s, and the rudder angle is 25°. The simulated ship motion under crossflow conditions is shown in Table 3 below. The simulated ship maneuverability under crossflow limits is shown in [the table below]. Figures 2-6 .

[0186] Table 3 Simulation parameters of ship maneuvering motion under crossflow limit conditions

[0187]

[0188] like Figures 2 to 6 As shown, the ship's speed on the opposite shore is V. b =0.5m / s, and the transverse velocity is V. y Under the condition of a current speed of 0.3 m / s and uniform distribution, for Class I waterways, the crosscurrent area is 80 m long, allowing a 3000t cargo ship (95m × 16.2m × 3.2m) to safely land on the beach; for Class II waterways, the same crosscurrent area length allows a 2000t cargo ship (90m × 14.8m × 2.6m) to safely land on the beach; for Class III waterways, the same crosscurrent area length allows a 1000t cargo ship (85m × 10.8m × 2.0m) to safely land on the beach; for Class IV waterways, the same crosscurrent area length allows a 500t cargo ship (67.5m × 10.8m × 1.6m) to safely land on the beach; and for Class V waterways, the same crosscurrent area length allows a 300t cargo ship (55m × 8.6m × 1.3m) to safely land on the beach. Figures 2-6 It can be seen that when the cross current is 0.3 m / s, representative vessels in each level of the waterway can resist the influence of the cross current to a certain extent by manipulating the rudder angle, ensuring that the vessels just do not exceed the safety boundary of the waterway and can achieve safe navigation.

[0189] (1) Relationship between drift velocity and crossflow velocity

[0190] Representative vessels from inland waterways of grades I to V (vessel parameters are shown in Table 1) were selected, assuming a vessel speed of Vs = 0.5 m / s on the opposite bank and a rudder angle of 25°. A mathematical model of vessel maneuvering motion was used to simulate the motion of vessels under five different cross-current conditions, and the relationship between the drift velocity and the cross-current velocity during the upstream journey of five tonnage vessels was obtained.

[0191] Depend on Figure 7 It can be seen that the drift speed V f With crossflow velocity V y The relationship is linear, V f =kV y +n. Because the ship is also subject to the resistance of the surrounding water flow, the cross-current force must reach a certain value for the ship to overcome the resistance and drift laterally. Therefore, in V y Before reaching a certain value, the drift velocity is 0, so the constant n must be less than or equal to zero.

[0192] A specific analysis was conducted on waterways of different grades, and the relationship between the drift velocity and the crossflow velocity for different waterways is shown in Table 4.

[0193] Table 4 Relationship between drift velocity and crossflow

[0194]

[0195] As shown in Table 4, the lateral drift speed of a vessel is mainly related to the lateral current velocity, and is also affected by the channel grade and ship hull parameters. In waterways of all grades, cross currents can cause vessels to drift laterally; the greater the lateral current velocity, the greater the lateral drift speed. By averaging the coefficients of the five equations, a comprehensive relationship between lateral drift speed and cross current velocity applicable to inland waterways of grades I to V can be obtained.

[0196] V f =1.08V y -0.08 (21)

[0197] In equation (21): V f V is the drift velocity, in m / s; y The velocity is the crossflow velocity, in m / s.

[0198] (2) Analyze the correspondence between cross current and navigation drift angle.

[0199] When a ship navigates in a waterway, its track gradually deviates from the centerline due to the force of crosscurrents, creating an angle between the bow direction and the direction of navigation. This angle is called the ship's drift angle, denoted by β. According to the "Inland Waterway Navigation Standards" (GB50139-2014), different waterway classes have different requirements for the drift angle. For example, in Class I to III waterways, the drift angle for a ship or convoy should be 3°, while in Class IV to V waterways, it should be 2°.

[0200] To further verify the influence of crossflow on the ship's drift angle under different crossflow conditions, we assume the ship is sailing upstream (i.e., on the beach), fully loaded, and temporarily ignores the effects of the bank wall effect and other factors such as wind. The current velocity is taken as 3.0 m / s under unfavorable conditions, the ship's speed on the opposite bank is 0.5 m / s, and the rudder angle is 25°. We simulate the ship's motion in various channel levels when the crossflow velocity is 0.32–0.50 m / s, obtaining the variation of the drift angle, analyzing the relationship between the crossflow and the drift angle, and plotting the ship's drift angle β against the crossflow velocity V. y Relationship diagram (see) Figure 8 ).

[0201] Figure 8 This figure reflects the relationship between the ship's drift angle and the crossflow velocity in waterways of different grades. As can be seen from the figure, within the same waterway grade, the ship's drift angle and the crossflow velocity are linearly related; the greater the crossflow velocity, the more severe the ship's drift, and the larger the drift angle. For different waterways, the higher the waterway grade, the larger the drift angle. The relationship between the crossflow magnitude and the ship's drift angle is shown in Table 5.

[0202] Table 5. Relationship between different crosscurrents and ship drift angle

[0203]

[0204]

[0205] Table 5 compares the maximum drift angles of ships navigating in different crosscurrent conditions in waterways of various grades. The table shows that within the crosscurrent velocity range of 0.3–0.5 m / s, the drift angle is 3.0°–5.0° in Grade I waterways; 2.5°–4.5° in Grade II waterways; 2.0°–4.0° in Grade III waterways; 1.5°–3.0° in Grade IV waterways; and 1.0°–2.5° in Grade V waterways. Furthermore, as the waterway grade increases, the drift angle of the ship gradually increases, generally conforming to…

[0206] The requirements of the Inland Waterway Navigation Standard (GB50139-2014).

[0207] (3) The required channel range limit under simulated crossflow conditions exceeding the standard.

[0208] Under the influence of crosscurrents, ships experience lateral displacement and yaw, leading to drift speed and drift angle, causing them to drift laterally along the width of the channel. When navigating within the channel, ship hull parameters, ship speed on the opposite bank, water depth ratio, and width all affect the degree of lateral movement. Furthermore, the size of the crosscurrent region also influences the extent of the ship's drift; the larger the crosscurrent region, the greater the ship's drift. If the crosscurrent's range is smaller than a certain value, the ship can resist its influence by maneuvering the rudder angle, ensuring it does not cross the channel safety line and can successfully land on the beach.

[0209] To further explore the maximum safety of crossflows exceeding the standard, we assumed the width of the crossflow range to be equal to the width of a single-lane channel, the current velocity to be 3.0 m / s, the ship's oncoming speed to the shore to be 0.5 m / s, and the rudder angle to be 25°. We simulated the ship's navigation state under different crossflow ranges exceeding the standard, obtaining the maximum crossflow range that a ship can safely navigate under these conditions. Table 6 shows the maximum crossflow range that a ship can safely navigate under different crossflow conditions exceeding the standard.

[0210] Table 6. Maximum Crossflow Range that Ships Can Withstand for Safe Navigation Under Excessive Crossflow Conditions.

[0211]

[0212] Even with a fixed width of the crossflow region exceeding the standard, the length L of the crossflow region also affects the ship's lateral drift; the longer the crossflow region, the greater the ship's drift. If the length of the crossflow region is less than a certain value L... d With proper rudder control, the vessel can resist the effects of crosscurrents, ensuring it does not exceed the safety line of the waterway and can successfully land on the beach.

[0213] Figure 9 This curve reflects the relationship between the maximum crossflow range length that a ship can safely navigate under conditions of excessive crossflow and the crossflow velocity. It is evident that the maximum crossflow range length that a ship can safely navigate under conditions of excessive crossflow is related to parameters such as crossflow velocity, waterway grade, and ship dimensions, but the safe value L for the crossflow range length remains constant. d With crossflow velocity V y The relationship between them is not a simple linear one; further analysis is needed to understand their relationship.

[0214] When a ship passes through a region of uniform crossflow, it will deviate laterally from the centerline of the channel by a certain distance, which is the ship's drift distance P. d Its value depends on the drift velocity V f And the time t that the ship spends in the crossflow area. The time t that the ship spends in the crossflow area is t = L / V s (where L is the length of the crossflow region, V) s (Speed ​​of the ship on the opposite shore).

[0215] Pd =V f ·t (22)

[0216] V f =k1V y -n (23)

[0217] In equations (22) and (23): P d V represents the drift distance of the ship, in meters (m). f t is the drift velocity, m / s; t is the time, s; k1 and n are parameters related to the channel grade and ship dimensions.

[0218] Therefore, the length L of the crossflow region can be determined by the following formula:

[0219]

[0220] In equation (24), P d V is the drift distance of the ship. y V is the transverse flow velocity. s is the ship's speed on the opposite shore, and k2 is a parameter related to the waterway grade and ship size.

[0221] This embodiment explores the impact of crosscurrents on ships within a fixed channel; therefore, the fixed drift distance is the width B of the ship's upstream track within the channel. d The maximum length L of the crossflow region d It can be calculated using the following formula:

[0222]

[0223] In equation (25), B d V is the width of the upstream track of a ship within the channel. y V is the transverse flow velocity. s is the ship's speed on the opposite shore, and k2 is a parameter related to the waterway grade and ship size.

[0224] According to the structural form of equation (25), L d ~V s / V y The relationship between the two channels is linear, and the relationship between different channel grades is shown in Table 7.

[0225] Table 7. Safe values ​​for the length of the crossflow area in Class I to V waterways and V s / V y Relationship

[0226]

[0227]

[0228] Depend on Figures 10-14It is evident that the safe value for the length of the crossflow area is related not only to the lateral current velocity and the ship's speed on the opposite bank, but also to the channel grade and ship type. Within the same channel grade, the greater the lateral current velocity, the smaller the safe value for the length of the crossflow area; the higher the channel grade, the greater the safe value for the length of the crossflow area.

[0229] By combining the values, the safe value of the length of the crossflow area in Class I to V inland waterways can be obtained. s / V y The relationship is:

[0230]

[0231] In equation (26): L d B is the safe length of the crossflow region, in meters. d V is the width of the uplink trackband, in meters. s V is the ship's speed on the opposite shore, in m / s; y The velocity is the crossflow velocity, in m / s.

[0232] (4) The required channel widening value under simulated crossflow conditions.

[0233] Under the influence of crossflows, ships will drift laterally. In natural waterways, for sections with excessive crossflows, waterway widening and deepening are necessary to ensure safe navigation. Based on numerous simulation parameters of typical representative ships navigating under different waterway grades and crossflow conditions, this study analyzes and obtains the safe navigation limit states and key parameter thresholds for representative ships passing through tributary confluences. The focus is on ship motion parameters under excessive crossflows, including waterway grade, ship dimensions, crossflow velocity, and crossflow range. The correspondence between excessive crossflows and main channel dimensions is derived, and the required main channel dimensions for safe navigation under different waterway grades and crossflow magnitudes are obtained, including the increased channel width compared to traditional channel dimensions. The simulated ship handling conditions under excessive crossflows are shown in Table 8.

[0234] Table 8 Simulation of Ship Maneuvering Conditions under Excessive Crossflow

[0235]

[0236]

[0237] Without considering the effects of wind, waves, etc., each representative vessel navigates in a uniform crossflow area, parallel to the channel centerline. The vessel's speed on the opposite bank is 0.5 m / s, and the crossflow velocity is V. y Simulations were conducted under the conditions of 0.35 m / s, 0.4 m / s, 0.45 m / s, 0.5 m / s, 0.55 m / s, and 0.6 m / s, and the results are as follows: Figures 15-29 .

[0238] In a Class I waterway, assuming the representative vessel is a fully loaded 3000t cargo ship with a width of 100m, such as... Figure 15 and Figure 16 When V y =0.60m / s, and when the crosscurrent range is 40m long, the ship's drift distance will reach 50m, exceeding the width of the upstream channel. Therefore, if Figure 17 The diagram shows the relationship between the crossflow exceeding the standard in Class I waterways and the waterway widening value. The waterway widening value under the crossflow exceeding the standard in Class I waterways should conform to Table 9.

[0239] Table 9. Relationship between the extent of crossflow exceeding the standard and the widening value of the navigation width (Class I waterway)

[0240]

[0241] In a Class II waterway, assuming the representative vessel is a fully loaded 2000t cargo ship with a width of 75m, such as... Figure 18 and Figure 19 When V y =0.60m / s, and when the length of the cross current is 27m, the ship's drift distance will reach 35m, exceeding the width of the upstream channel.

[0242] like Figure 20 When the lateral current velocity is less than 0.6 m / s, as long as the length of the lateral current area does not exceed 20 meters, ships will not cross the channel safety line and can proceed to the beach. Therefore, in Class II waterways, when the length of the lateral current exceeding the standard exceeds 20 meters, the channel width needs to be appropriately widened according to Table 10.

[0243] Table 10 Relationship between Excessive Crossflow Range and Channel Widening Values ​​(Class II Waterway)

[0244]

[0245] In a Class III waterway, assuming the representative vessel is a fully loaded 1000t cargo ship with a width of 60m, by Figure 21 It is known that when the crossflow velocity exceeds 0.3 m / s, the crossflow has a significant impact on ship navigation. The ship's own rudder force is insufficient to resist the effect of the crossflow, and it will deviate from the center line of the channel and drift laterally towards the shore, resulting in the ship being unable to navigate safely. Figure 22 This reflects a linear relationship between the length of the crossflow region and the ship's drift distance; the longer the crossflow region, the greater the ship's drift distance. When V y When the crossflow speed is 0.60 m / s and the length of the crossflow range is 25 m, the ship's drift distance will reach 30 m, exceeding the width of the upstream channel. Therefore, in cases of excessive crossflow, it is necessary to propose the channel width required for safe navigation of ships under different crossflow sizes within a Class III channel, based on the correspondence between the excessive crossflow and the dimensions of the main channel.

[0246] The relationship between the excessive crossflow in Class III waterways and the waterway widening value is shown in the figure. Figure 23 The channel widening value needs to consider not only the magnitude of the crossflow velocity but also the length of the crossflow region. When a 1000t cargo ship passes through a uniformly distributed crossflow region, if the crossflow velocity is in the range of 0.3m / s to 0.6m / s, the ship will not exceed the channel safety line as long as the length of the crossflow region does not exceed 15m.

[0247] Therefore, in Class III waterways, when the length of the crossflow exceeds 15m, the waterway width needs to be appropriately increased according to Table 11.

[0248] Table 11 Relationship between Excessive Crossflow Range and Channel Widening Value (Class III Waterway)

[0249]

[0250] In a Class IV waterway, it is assumed that the representative vessel is a fully loaded 500t cargo ship with a width of 50m. Figure 24 and Figure 25 When V y =0.60m / s, and when the length of the cross current is 21m, the ship's drift distance will reach 25m, exceeding the width of the upstream channel.

[0251] The relationship between the excessive crossflow and the channel widening value in Class IV waterways is shown in the figure. Figure 26 It can be seen that when a 500t cargo ship passes through a uniformly distributed crossflow area, and the crossflow velocity is in the range of 0.3m / s to 0.6m / s, the length of the crossflow area is less than 10m, and the ship will not exceed the channel safety line. Therefore, in Class IV waterways, when the length of the crossflow distribution exceeds 10m, the channel width needs to be appropriately widened according to Table 12.

[0252] Table 12 Relationship between Exceeding Crossflow Range and Increase in Navigation Width (Class IV Waterway)

[0253]

[0254] In a Class V waterway, assuming the representative vessel is a fully loaded 300t cargo ship with a width of 40m, by Figure 27 and Figure 28 When V y =0.60m / s, when the crosscurrent range is 15m long, the ship's drift distance will reach 20m, exceeding the width of the upstream channel. The relationship between excessive crosscurrent and channel widening value in Class V channels is shown in [reference needed]. Figure 29 It can be seen that when a 300t cargo ship passes through a uniformly distributed crossflow area, and the crossflow velocity is in the range of 0.3m / s to 0.6m / s, the length of the crossflow area is less than 8m, and the ship will not exceed the channel safety line. Therefore, in Class V waterways, when the length of the crossflow distribution exceeds 8m, the channel width needs to be appropriately widened according to Table 13.

[0255] Table 13 Relationship between Exceeding Crossflow Range and Increase in Navigation Width (Class V Waterway)

[0256]

[0257] Depend on Figures 15-29 It is evident that a ship's lateral drift distance is related not only to the magnitude of the crosscurrent velocity but also to the length of the crosscurrent region. The length of the crosscurrent region exceeding the standard has a linear relationship with the drift distance. Given a fixed crosscurrent, the greater the length of the crosscurrent region exceeding the standard, the greater the ship's lateral drift. The greater the crosscurrent velocity, the greater the ship's drift velocity, and the greater the lateral drift when the ship passes through that region. Furthermore, the channel widening value should consider not only the magnitude of the crosscurrent velocity but also the length of the crosscurrent region. The greater the crosscurrent velocity, the greater the channel widening value; with the same crosscurrent velocity, the longer the crosscurrent region, the greater the increase in navigable clearance.

[0258] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Under the teachings of the present invention, modifications can be made to these features and embodiments to adapt to specific situations and materials without departing from the spirit and scope of the invention. The embodiments described in this invention are only a part of the embodiments of the invention, not all of them. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. Therefore, the invention is not limited to the specific embodiments disclosed herein, and all other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for determining the width of a waterway under conditions of excessive crossflow, characterized in that, Includes the following steps: S1. Collect basic waterway data; S2. Based on the basic data of the waterway, construct a two-dimensional planar mathematical model of water flow; S3. Establish a mathematical model of ship maneuvering motion based on ship motion equations; S4. Based on the mathematical model of ship maneuvering motion, the ship's navigation attitude is simulated under different waterway grades and different cross currents, and the navigation motion parameters of the ship under the cross currents are obtained under different waterway grades. S5. Based on the navigation motion parameters of representative ships under the action of excessive cross current, the quantitative relationship between excessive cross current and the channel width widening value under different channel grades is obtained through simulation. In step S5, based on the navigation motion parameters representing ships under the influence of excessive cross current, a quantitative relationship between excessive cross current and channel width enhancement value under different channel grades is obtained through simulation, including the following steps: S5.1 Based on the relationship between the ship's drift speed and the crossflow, the ship's motion under different crossflow conditions is simulated using a mathematical model of ship maneuvering motion. The relationship between the ship's drift speed and the crossflow speed in the channel is then obtained. Specifically, under the conditions of a ship's onshore speed Vs = 0.5 m / s and a rudder angle of 25°, the comprehensive relationship between the drift speed and the crossflow speed in the channel is as follows: ； In the formula: This is the drift velocity, measured in m / s; The crossflow velocity is expressed in m / s. S5.2 Analyze the relationship between cross current and navigation drift angle to obtain the curve showing the change of ship navigation drift angle with cross current speed in the channel; S5.

3. Based on the above-mentioned relationship between the ship's drift speed and the cross current in the channel, and the corresponding relationship between the cross current and the navigation drift angle, the required channel range limit and the required channel widening value under the condition of excessive cross current are simulated; among them, under the conditions of a current speed of 3.0 m / s, a ship's onshore speed of 0.5 m / s, and a rudder angle of 25°, the relationship of the required channel range limit under the condition of excessive cross current is as follows: ； In the formula: This is the safe length of the crossflow region, in meters (m). The width of the uplink trackband is in meters. The speed of the ship on the opposite shore is expressed in m / s. The crossflow velocity is expressed in m / s.

2. The method for determining channel width under conditions of excessive crossflow as described in claim 1, characterized in that, In step S2, the planar two-dimensional water flow mathematical model is constructed using the average water depth finite element method, and the parameters of the waterway at different time periods are simulated. Specifically, this includes the following steps: S2.1, Set the boundary conditions for the model; S2.

2. Based on the fundamental equations of the finite element method of average water depth, a set of nonlinear equations is obtained by numerical discretization of the fundamental equations. S2.3 Solve the above nonlinear equations to obtain the parameter values ​​of the waterway at different time periods.

3. The method for determining channel width under conditions of excessive crossflow as described in claim 2, characterized in that, The parameters of the waterway at different times include water level, water depth, current velocity, and current direction.

4. The method for determining channel width under conditions of excessive crossflow as described in claim 2, characterized in that, In step S2.1, the boundary conditions of the two-dimensional planar water flow mathematical model include the inlet boundary, the outlet boundary, and the bank boundary.

5. The method for determining channel width under conditions of excessive crossflow according to claim 1, characterized in that, In step S4, the expressions for the ship's position and related parameters at any given time, representing the ship's navigation motion parameters under the influence of the excessive crossflow, are as follows: ； In the formula, the subscripts in the parameters Representing the Moment, Footprint Representing the time, For time increments, For the first Ships at all times Position in direction For the first Ships at all times Position in direction No. Ships at all times Position in direction For the first Ships at all times Position in direction For the hull and the water flow Relative velocity in the direction; For the hull and the water flow Relative velocity in the direction; This refers to the ship's bow turning angular velocity; The origin of the moving coordinate system is at Velocity in the direction; The velocity of the origin of the moving coordinate system in the y-direction; The absolute velocity of the water flow; The direction of water flow; This is the bow angle of the ship.

6. The method for determining channel width under conditions of excessive crossflow according to claim 1, characterized in that, In step S5.3, the required channel widening value under the excessive crossflow conditions is 0.3~182.6m; wherein, the ship navigates in a uniform crossflow area and is parallel to the centerline of the channel, the crossflow velocity ranges from 0.35 m / s to 0.6 m / s, the length of the crossflow area ranges from 10 to 80m, and the ship's speed on the opposite bank is 0.5m / s.

7. The method for determining channel width under conditions of excessive crossflow as described in claim 6, characterized in that, The required channel widening value under the excessive crossflow conditions can be applied to Class I to V waterways, wherein: The Class I waterway allows vessels with a tonnage of 3000t and a width of 100m. The representative vessel dimensions are overall length × beam × design draft = 95 × 16.2 × 3.2m. The corresponding range of cross current and waterway widening values ​​is 0.5~150.8m. The Class II waterway allows vessels with a tonnage of 2000t and a width of 75m. The representative vessel dimensions are overall length × beam × design draft = 90 × 14.8 × 2.6m. The corresponding range of cross current and waterway widening values ​​is 0.3~164.9m. The Class III waterway allows vessels with a tonnage of 1000t and a width of 60m. The representative vessel dimensions are overall length × beam × design draft = 85 × 10.8 × 2.0m. The corresponding range of cross currents and waterway widening values ​​is 3.5~174.1m. The Class IV waterway allows vessels with a tonnage of 500t and a width of 50m. The representative vessel dimensions are overall length × beam × design draft = 67.5 × 10.8 × 1.6m, and the corresponding cross current and waterway widening values ​​range from 2.3 to 182.6m. For Class V waterways, the vessel tonnage is 300t and the width is 40m. The representative vessel dimensions are overall length × beam × design draft = 55 × 8.6 × 1.3m. The corresponding range of cross current and waterway widening values ​​is 1.6~188.2m.

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