A mooring hydrodynamic calculation method for a submerged buoy based on an adaptive drag coefficient

Abstract

The application discloses a mooring buoy hydrodynamic calculation method based on an adaptive drag coefficient, belongs to the technical field of marine engineering and computer-aided calculation, and is used for calculating the mooring buoy hydrodynamic calculation, and comprises the following steps: setting a plurality of nodes, dividing the mooring cable of the buoy into a plurality of cable sections, and installing a mooring component at the node position; defining the time span of the hydrodynamic calculation, calculating the flow velocity vector and the flow velocity module at the node, and calculating the attack angle of the cable section corresponding to the node and the corresponding Reynolds number; calculating the drag coefficient by using the attack angle and the Reynolds number, introducing a mixing coefficient to update the drag coefficient, and calculating the hydrodynamic force at the node; based on the hydrodynamic force, establishing a three-way force balance equation at the node and iteratively solving until the convergence condition is met, and outputting the mooring buoy hydrodynamic response result. The application introduces the drag coefficient dynamic adjustment mechanism driven by the attack angle and the Reynolds number, and improves the calculation precision and stability of the mooring system under the condition of a complex flow field.

Description

Technical Field

[0001] This invention discloses a hydrodynamic calculation method for moored underwater mooring based on an adaptive resistance coefficient, belonging to the fields of marine engineering and computer-aided computing technology. Background Technology

[0002] Submersible mooring systems are widely used for long-term continuous observation of the marine dynamic environment. Their underwater attitude and stress state directly affect the actual working depth of the observation instruments and the data quality. Existing methods for calculating the attitude and hydrodynamics of submersible mooring systems are mostly based on static or quasi-static assumptions, with the Mooring Design & Dynamics (MD&D) model being a typical example.

[0003] The MD&D model typically uses a fixed drag coefficient Cd in drag force calculations. While this approach offers advantages in computational stability, it is essentially based on a steady drag assumption, neglecting the dynamic response characteristics of the drag coefficient as a function of local flow velocity, angle of attack, and Reynolds number. In strong current and multi-timescale flow environments, this assumption fails to accurately reflect the true hydrodynamic response of the mooring cable and mooring components, leading to increased errors in the calculation of mooring attitude and tension.

[0004] Therefore, there is an urgent need for a hydrodynamic calculation method that can introduce an adaptive adjustment mechanism for the drag coefficient while maintaining the stability of the traditional mooring calculation framework. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrodynamic calculation method for moored underwater mooring based on an adaptive drag coefficient, in order to solve the problem in the prior art that ignores the dynamic response characteristics of the drag coefficient as a function of local flow velocity, angle of attack and Reynolds number. In strong current and multi-timescale flow environments, it is difficult to accurately reflect the real hydrodynamic response of the cable and mooring components, which leads to increased errors in the calculation of the mooring attitude and tension.

[0006] A method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient includes:

[0007] S1. Set up several nodes and divide the mooring cable into several cable segments. Install mooring components at the node positions. Define the time span for hydrodynamic calculation and calculate the velocity vector and velocity modulus at the nodes within the time span. Calculate the angle of attack of the cable segment corresponding to the node using the spatial geometric direction of the cable segment and the velocity vector at the node. Calculate the Reynolds number corresponding to the node based on the velocity modulus at the node, the characteristic scale of the cable segment, and the fluid kinematic viscosity.

[0008] S2. Calculate the initial drag coefficient and adaptive correction term using the angle of attack and Reynolds number. Calculate the drag coefficient based on the initial drag coefficient and adaptive correction term. After updating the position and attitude of the node, calculate the updated drag coefficient using the mixing coefficient based on the drag coefficient of the previous time span. Calculate the hydrodynamics at the node based on the updated drag coefficient. Establish the triaxial force balance equation at the node based on the hydrodynamics.

[0009] S3. Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2, iteratively solve the triaxial force balance equation until the convergence condition is met, and output the hydrodynamic response results of the moored mooring.

[0010] S1 includes, S1.1, setting up along the axis of the buoy cable. The underwater mooring cable is divided into several nodes based on these nodes. For a cable segment, let the index of the node be... , The mooring components are installed at the node locations. The basic parameters for these mooring components include the geometric dimensions and characteristic scales of the cable segment corresponding to the node, the effective weight and buoyancy of the mooring components in the water, the initial spatial geometric orientation of adjacent cable segments in three-dimensional space, and the initial drag coefficient corresponding to the mooring components. The effective weight of the mooring component is its weight in air minus its buoyancy; the geometry includes the length of the cable segment. Diameter of cable segment and the cross-sectional area of ​​the cable segment The feature scale includes the feature length. Equivalent projected area of ​​mooring components ;

[0011] The mooring component includes a basic computational unit, through which force balance equations are established, drag coefficients are calculated, and attitude is updated.

[0012] Assume that the cable segment only bears axial tension, and the tension between adjacent nodes is transmitted along the direction of the cable segment.

[0013] S1 includes S1.2, defining the time span for hydrodynamic calculations. ,right The average of all velocity data within the node is used as the velocity vector at the node's location;

[0014] Determine the cable positions of each equipment node in the underwater mooring system:

[0015] ;

[0016] In the formula, For the first The cable position at each node, For the first The node and the first The cable length between nodes

[0017] Read the depth time series of a device node equipped with a depth sensor;

[0018] Based on the cable length relationship between device nodes without depth sensors and those with depth sensors, the depth time series of the device nodes without depth sensors is determined. Assume there is a node B without a depth sensor between node A and node C, and the cable position of node A is... The cable position at node B is The cable position at node C is ,satisfy Calculate the proportionality coefficient :

[0019] ;

[0020] Let the depth time series of node A be: The depth time series of node C is Depth time series of node B for:

[0021] ;

[0022] Based on the depth time series of each node, the flow velocity data of different depth layers are mapped to the corresponding nodes using linear interpolation to obtain the flow velocity time series of each node.

[0023] Statistical analysis is performed on the flow velocity time series of the nodes, let the th node be... Nodes The flow rate at time is Set an abnormal flow rate threshold ,like Remove ,calculate and The average flow velocity as the first Nodes Flow rate after real-time correction;

[0024] For those located at the set boundary threshold The flow velocity observation boundary region is defined by taking the shallowest and deepest nodes as starting points, respectively. The distance is the vertical downward distance from the node with the shallowest depth. The deepest node is vertically upward. For equipment nodes in the flow velocity observation boundary region, compensation is performed using an inverse distance weighting method for flow velocity data from adjacent depth layers, and the flow velocity data is smoothed in the vertical direction.

[0025] ;

[0026] In the formula, For the smoothed first The flow rate of the layer, For the first The flow rate of the layer, To smooth out half the window width;

[0027] Obtain the flow velocity vector at the location of each node. , Calculate the velocity modulus at the node:

[0028] ;

[0029] In the formula, This represents the velocity component in the eastward direction. This represents the velocity component in the north direction. The vertical velocity component is... It is a scalar symbol.

[0030] S1 includes S1.3, calculating the spatial geometric direction of the cable segment corresponding to the node, and combining the spatial geometric direction of the cable segment with... The angle between the directions is defined as the angle of attack of the cable segment corresponding to the node. .

[0031] S1 includes, S1.4, according to Feature scale and fluid kinematic viscosity Calculate the Reynolds number corresponding to the node. :

[0032] .

[0033] S2 includes, S2.1, let... For node indexing, use the corresponding node and The empirical formula is used to calculate the first Initial drag coefficient of each node ;

[0034] Let the first Each node drag coefficient ,right Perform a Taylor expansion:

[0035] ;

[0036] In the formula, for The drag coefficient at that time The function equals The values ​​of derivatives at each order;

[0037] set up yes The influence coefficient, let ,based on The even function property, let Based on the symmetry of the cable segments, ;

[0038] Definition of the first Each node Contribution to the adaptive correction term :

[0039] ;

[0040] Definition of the first Each node Contribution to the adaptive correction term :

[0041] ;

[0042] In the formula, for The influence coefficient;

[0043] Using the first The corresponding nodes and Calculate the adaptive correction term :

[0044] ;

[0045] use and Calculate the first Resistance coefficient at each node :

[0046] .

[0047] S2 includes S2.2, after the attitude and position of the nodes are updated, the Reynolds number and angle of attack of each node are recalculated, and the drag coefficient of each node is updated synchronously based on the updated Reynolds number and angle of attack.

[0048] Introducing the mixing coefficient The updated drag coefficient is:

[0049] ;

[0050] In the formula, For the first The drag coefficient after the next iteration For the first The drag coefficient after the next iteration As the reference drag coefficient, This is a correction term for the drag coefficient.

[0051] S2 includes S2.3, calculating the hydrodynamic forces acting on the nodes using the updated drag coefficient. :

[0052] ;

[0053] In the formula, For direction variables, , The direction is east. North direction Vertical The density of water, For the node perpendicular to Cross-sectional area in the direction, for The velocity component in the direction.

[0054] S2 includes S2.4, establishing a northeast-northeast coordinate system with the nodes as the origin, and establishing triaxial force equilibrium equations for each node:

[0055] ;

[0056] ;

[0057] ;

[0058] In the formula, To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics For the first The cable segment at the first node facing the bottom of the underwater mooring is paired with the first... The tension applied at each node, For the first The cable segment at the first node facing the top of the underwater mooring is paired with the first... The tension applied at each node, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first Buoyancy at each node;

[0059] Solving the triaxial force equilibrium equations yields the tension in the cable segment. Spatial geometric direction of cable segment This leads to the derivation of the node's three-dimensional coordinates. .

[0060] S3 includes setting a convergence condition: the change in force on a node is less than a preset threshold for the change in force between two adjacent iterations. Or, the change in drag coefficient between two consecutive iterations is less than a preset threshold for the change in drag coefficient. ;

[0061] Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2 until the convergence condition is met, and output the hydrodynamic response results of the moored buoy.

[0062] The hydrodynamic response results of the moored buoy include the attitudes of each node of the moored buoy after convergence. Cable tension distribution after convergence at each node The overall hydrodynamic response results after convergence, including the drag coefficients of each node after convergence. Hydrodynamics of each node after convergence The displacement of the buoy after convergence and the shape of the cable after convergence;

[0063] The value after convergence. For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics.

[0064] Compared with existing technologies, this invention has the following advantages: By introducing angle of attack and Reynolds number to adaptively correct the drag coefficient, this invention can more accurately reflect the force characteristics of cables and mooring components under actual sea conditions, avoiding the errors caused by using a constant drag coefficient in traditional methods, and significantly improving the accuracy of hydrodynamic calculations; It considers the changes in flow velocity and direction with depth and time, and through node processing and interpolation techniques, accurately maps the measured flow velocity data to each node, and combined with an adaptive drag coefficient update mechanism, enables the calculation model to dynamically respond to changes in the marine environment, making it suitable for the analysis of mooring systems under complex ocean current conditions; By establishing a triaxial force balance equation and solving iteratively, it can output complete response results including node attitude, cable tension distribution, hydrodynamic distribution, and cable shape, providing comprehensive data support for the design and optimization of mooring systems. Attached Figure Description

[0065] Figure 1 This is the adaptive convergence logic of the method of this invention;

[0066] Figure 2 It is the eastward flow velocity input of the model;

[0067] Figure 3 It is the northward flow velocity input for the model;

[0068] Figure 4 This is the initial improvement effect of the method of the present invention on the high-frequency part (12h) of attitude simulation. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0070] A method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient includes:

[0071] S1. Set up several nodes and divide the mooring cable into several cable segments. Install mooring components at the node positions. Define the time span for hydrodynamic calculation and calculate the velocity vector and velocity modulus at the nodes within the time span. Calculate the angle of attack of the cable segment corresponding to the node using the spatial geometric direction of the cable segment and the velocity vector at the node. Calculate the Reynolds number corresponding to the node based on the velocity modulus at the node, the characteristic scale of the cable segment, and the fluid kinematic viscosity.

[0072] S2. Calculate the initial drag coefficient and adaptive correction term using the angle of attack and Reynolds number. Calculate the drag coefficient based on the initial drag coefficient and adaptive correction term. After updating the position and attitude of the node, calculate the updated drag coefficient using the mixing coefficient based on the drag coefficient of the previous time span. Calculate the hydrodynamics at the node based on the updated drag coefficient. Establish the triaxial force balance equation at the node based on the hydrodynamics.

[0073] S3. Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2, iteratively solve the triaxial force balance equation until the convergence condition is met, and output the hydrodynamic response results of the moored mooring.

[0074] S1 includes, S1.1, setting up along the axis of the buoy cable. The underwater mooring cable is divided into several nodes based on these nodes. For a cable segment, let the index of the node be... , The mooring components are installed at the node locations. The basic parameters for these mooring components include the geometric dimensions and characteristic scales of the cable segment corresponding to the node, the effective weight and buoyancy of the mooring components in the water, the initial spatial geometric orientation of adjacent cable segments in three-dimensional space, and the initial drag coefficient corresponding to the mooring components. The effective weight of the mooring component is its weight in air minus its buoyancy; the geometry includes the length of the cable segment. Diameter of cable segment and the cross-sectional area of ​​the cable segment The feature scale includes the feature length. Equivalent projected area of ​​mooring components ;

[0075] The mooring component includes a basic computational unit, through which force balance equations are established, drag coefficients are calculated, and attitude is updated.

[0076] Assume that the cable segment only bears axial tension, and the tension between adjacent nodes is transmitted along the direction of the cable segment.

[0077] S1 includes S1.2, defining the time span for hydrodynamic calculations. ,right The average of all velocity data within the node is used as the velocity vector at the node's location;

[0078] Determine the cable positions of each equipment node in the underwater mooring system:

[0079] ;

[0080] In the formula, For the first The cable position at each node, For the first The node and the first The cable length between nodes

[0081] Read the depth time series of a device node equipped with a depth sensor;

[0082] Based on the cable length relationship between device nodes without depth sensors and those with depth sensors, the depth time series of the device nodes without depth sensors is determined. Assume there is a node B without a depth sensor between node A and node C, and the cable position of node A is... The cable position at node B is The cable position at node C is ,satisfy Calculate the proportionality coefficient :

[0083] ;

[0084] Let the depth time series of node A be: The depth time series of node C is Depth time series of node B for:

[0085] ;

[0086] Based on the depth time series of each node, the flow velocity data of different depth layers are mapped to the corresponding nodes using linear interpolation to obtain the flow velocity time series of each node.

[0087] Statistical analysis is performed on the flow velocity time series of the nodes, let the th node be... Nodes The flow rate at time is Set an abnormal flow rate threshold ,like Remove ,calculate and The average flow velocity as the first Nodes Flow rate after real-time correction;

[0088] For those located at the set boundary threshold The flow velocity observation boundary region is defined by taking the shallowest and deepest nodes as starting points, respectively. The distance is the vertical downward distance from the node with the shallowest depth. The deepest node is vertically upward. For equipment nodes in the flow velocity observation boundary region, compensation is performed using an inverse distance weighting method for flow velocity data from adjacent depth layers, and the flow velocity data is smoothed in the vertical direction.

[0089] ;

[0090] In the formula, For the smoothed first The flow rate of the layer, For the first The flow rate of the layer, To smooth out half the window width;

[0091] Obtain the flow velocity vector at the location of each node. , Calculate the velocity modulus at the node:

[0092] ;

[0093] In the formula, This represents the velocity component in the eastward direction. This represents the velocity component in the north direction. The vertical velocity component is... It is a scalar symbol.

[0094] S1 includes S1.3, calculating the spatial geometric direction of the cable segment corresponding to the node, and combining the spatial geometric direction of the cable segment with... The angle between the directions is defined as the angle of attack of the cable segment corresponding to the node. .

[0095] S1 includes, S1.4, according to Feature scale and fluid kinematic viscosity Calculate the Reynolds number corresponding to the node. :

[0096] .

[0097] S2 includes, S2.1, let... For node indexing, use the corresponding node and The empirical formula is used to calculate the first Initial drag coefficient of each node ;

[0098] Let the first Each node drag coefficient ,right Perform a Taylor expansion:

[0099] ;

[0100] In the formula, for The drag coefficient at that time The function equals The values ​​of derivatives at each order;

[0101] set up yes The influence coefficient, let ,based on The even function property, let Based on the symmetry of the cable segments, ;

[0102] Definition of the first Each node Contribution to the adaptive correction term :

[0103] ;

[0104] Definition of the first Each node Contribution to the adaptive correction term :

[0105] ;

[0106] In the formula, for The influence coefficient;

[0107] Using the first The corresponding nodes and Calculate the adaptive correction term :

[0108] ;

[0109] use and Calculate the first Resistance coefficient at each node :

[0110] .

[0111] S2 includes S2.2, after the attitude and position of the nodes are updated, the Reynolds number and angle of attack of each node are recalculated, and the drag coefficient of each node is updated synchronously based on the updated Reynolds number and angle of attack.

[0112] Introducing the mixing coefficient The updated drag coefficient is:

[0113] ;

[0114] In the formula, For the first The drag coefficient after the next iteration For the first The drag coefficient after the next iteration As the reference drag coefficient, This is a correction term for the drag coefficient.

[0115] S2 includes S2.3, calculating the hydrodynamic forces acting on the nodes using the updated drag coefficient. :

[0116] ;

[0117] In the formula, For direction variables, , The direction is east. North direction Vertical The density of water, For the node perpendicular to Cross-sectional area in the direction, for The velocity component in the direction.

[0118] S2 includes S2.4, establishing a northeast-northeast coordinate system with the nodes as the origin, and establishing triaxial force equilibrium equations for each node:

[0119] ;

[0120] ;

[0121] ;

[0122] In the formula, To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics For the first The cable segment at the first node facing the bottom of the underwater mooring is paired with the first... The tension applied at each node, For the first The cable segment at the first node facing the top of the underwater mooring is paired with the first... The tension applied at each node, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first Buoyancy at each node;

[0123] Solving the triaxial force equilibrium equations yields the tension in the cable segment. Spatial geometric direction of cable segment This leads to the derivation of the node's three-dimensional coordinates. .

[0124] S3 includes setting a convergence condition: the change in force on a node is less than a preset threshold for the change in force between two adjacent iterations. Or, the change in drag coefficient between two consecutive iterations is less than a preset threshold for the change in drag coefficient. ;

[0125] Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2 until the convergence condition is met, and output the hydrodynamic response results of the moored buoy.

[0126] The hydrodynamic response results of the moored buoy include the attitudes of each node of the moored buoy after convergence. Cable tension distribution after convergence at each node The overall hydrodynamic response results after convergence, including the drag coefficients of each node after convergence. Hydrodynamics of each node after convergence The displacement of the buoy after convergence and the shape of the cable after convergence;

[0127] The value after convergence. For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics.

[0128] The following description, in conjunction with the accompanying drawings and embodiments, provides further details. The adaptive convergence logic of the method of the present invention is as follows: Figure 1 As shown, the initialization begins first. and Then enter the initial... and Then update and and update Then judge If the conditions are not met, return to update. and Steps, if the conditions are met, output. ;in Angle of attack for the current time span, For the angle of attack over the previous time span, This is the angle of attack convergence threshold, which is usually set to 0.01 rad.

[0129] The underwater mooring system used in this embodiment includes a float, mooring lines, several observation equipment nodes arranged along the axis of the lines, and an anchoring structure. The relative positions of each equipment node on the lines are determined according to the underwater mooring deployment plan. Each node serves as the basic unit for hydrodynamic calculations and force balance analysis. , , , Set as Three-layer window moving average, with the window size determined based on ADCP interlayer spacing and observation noise level;

[0130] Calculated using empirical formulas :

[0131] .

[0132] First, based on the structural parameters of the underwater mooring system, the continuous mooring cables are discretized, nodes are set at the connection points of adjacent cable segments, and the connection relationships between nodes are established. Then, the time span for hydrodynamic calculations is determined, and the flow velocity and depth information acquired by the observation equipment is read. For some equipment nodes that do not directly acquire depth information, the equivalent depth of the corresponding node is determined based on the cable length relationship between it and nodes equipped with depth sensors, thereby constructing the depth time series for each equipment node.

[0133] Based on this, flow velocity observation data at different depths are mapped to corresponding nodes according to the depth of each device node, forming a node-level flow velocity time series. The flow velocity input contains significant multi-timescale variation characteristics, as illustrated in the diagram below. Figure 2 , Figure 3 As shown, this is used to characterize the complex background flow conditions that a mooring may encounter in a real marine dynamic environment.

[0134] After completing the input of flow velocity and structural parameters, according to Figure 1 The adaptive drag coefficient hydrodynamic calculation process for moored underwater vehicles (MAVs) is shown, which performs quasi-static iterative calculations on the MAV system. Specifically, in each iteration, the cable axis direction is determined based on the node positions and the spatial geometric relationships between adjacent cable segments, and the angle of attack and Reynolds number of the corresponding cable segment are calculated in conjunction with the velocity vector at the node.

[0135] Based on the angle of attack and Reynolds number, the drag coefficient corresponding to the node is adaptively corrected, and the hydrodynamic components of the node in the cable axis direction and its normal direction are calculated using the corrected drag coefficient. Subsequently, the hydrodynamic forces, along with the gravity, buoyancy, and cable tension acting on the node, are incorporated into the node's triaxial force equilibrium equations, updating the node position and cable attitude under quasi-static assumptions. The above process follows... Figure 1 The process shown is executed cyclically until the node's attitude and force state meet the convergence conditions.

[0136] Finally, the results of the mooring attitude and settlement response obtained using the method of this invention are compared with the results obtained using the traditional fixed drag coefficient quasi-static mooring calculation method. The results are illustrated in the figure below. Figure 4As shown in the figure. The comparative results show that, under conditions of strong current and multi-timescale velocity changes, the method of the present invention can more reasonably reflect the response characteristics of the mooring attitude as the flow changes, and effectively improve the deviation problem of traditional methods in the simulation of abnormal settlement and attitude response of moors.

[0137] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient, characterized in that, include: S1. Set up several nodes, divide the underwater mooring cable into several cable segments, and install mooring components at the node positions. Define the time span for hydrodynamic calculations, and calculate the velocity vector and velocity modulus at the nodes within the time span; using the spatial geometric direction of the cable segment and the velocity vector at the node, calculate the angle of attack of the cable segment corresponding to the node; and calculate the Reynolds number corresponding to the node based on the velocity modulus at the node, the characteristic scale of the cable segment, and the fluid kinematic viscosity. S2. Calculate the initial drag coefficient and adaptive correction term using the angle of attack and Reynolds number, and calculate the drag coefficient based on the initial drag coefficient and adaptive correction term; After the node's position and attitude are updated, the updated drag coefficient is calculated using the mixing coefficient based on the drag coefficient of the previous time span; the hydrodynamic force at the node is then calculated based on the updated drag coefficient. The triaxial force balance equation at the node is established based on hydrodynamics; S3. Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2, iteratively solve the triaxial force balance equation until the convergence condition is met, and output the hydrodynamic response results of the moored mooring.

2. The method for calculating the hydrodynamics of underwater mooring based on adaptive drag coefficient according to claim 1, characterized in that, S1 includes, S1.1, setting up along the axis of the buoy cable. The underwater mooring cable is divided into several nodes based on these nodes. For a cable segment, let the index of the node be... , The mooring components are installed at the node locations. The basic parameters for these mooring components include the geometric dimensions and characteristic scales of the cable segment corresponding to the node, the effective weight and buoyancy of the mooring components in the water, the initial spatial geometric orientation of adjacent cable segments in three-dimensional space, and the initial drag coefficient corresponding to the mooring components. The effective weight of the mooring component is its weight in air minus its buoyancy; the geometry includes the length of the cable segment. Diameter of cable segment and the cross-sectional area of ​​the cable segment The characteristic scale includes the characteristic length and the equivalent projected area of ​​the mooring component. The characteristic length is equal to the diameter of the cable segment. ; The mooring component includes a basic computational unit, through which force balance equations are established, drag coefficients are calculated, and attitude is updated. Assume that the cable segment only bears axial tension, and the tension between adjacent nodes is transmitted along the direction of the cable segment.

3. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 2, characterized in that, S1 includes S1.2, defining the time span for hydrodynamic calculations. ,right The average of all velocity data within the node is used as the velocity vector at the node's location; Determine the cable positions of each equipment node in the underwater mooring system: ； In the formula, For the first The cable position at each node, For the first The node and the first The cable length between nodes Read the depth time series of a device node equipped with a depth sensor; Based on the cable length relationship between device nodes without depth sensors and those with depth sensors, the depth time series of the device nodes without depth sensors is determined. Assume there is a node B without a depth sensor between node A and node C, and the cable position of node A is... The cable position at node B is The cable position at node C is ,satisfy Calculate the proportionality coefficient : ； Let the depth time series of node A be: The depth time series of node C is Depth time series of node B for: ； Based on the depth time series of each node, the flow velocity data of different depth layers are mapped to the corresponding nodes using linear interpolation to obtain the flow velocity time series of each node. Statistical analysis is performed on the flow velocity time series of the nodes, let the th node be... Nodes The flow rate at time is Set an abnormal flow rate threshold ,like Remove ,calculate and The average flow velocity as the first Nodes Flow rate after real-time correction; For those located at the set boundary threshold The flow velocity observation boundary region is defined by taking the shallowest and deepest nodes as starting points, respectively. The distance is the vertical downward distance from the node with the shallowest depth. The deepest node is vertically upward. For equipment nodes in the flow velocity observation boundary region, compensation is performed using an inverse distance weighting method for flow velocity data from adjacent depth layers, and the flow velocity data is smoothed in the vertical direction. ； In the formula, For the smoothed first The flow rate of the layer, For the first The flow rate of the layer, To smooth out half the window width; Obtain the flow velocity vector at the location of each node. , Calculate the velocity modulus at the node: ； In the formula, This represents the velocity component in the eastward direction. This represents the velocity component in the north direction. The vertical velocity component is... It is a scalar symbol.

4. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 3, characterized in that, S1 includes S1.3, calculating the spatial geometric direction of the cable segment corresponding to the node, and combining the spatial geometric direction of the cable segment with... The angle between the directions is defined as the angle of attack of the cable segment corresponding to the node. .

5. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 4, characterized in that, S1 includes, S1.4, according to Feature scale and fluid kinematic viscosity Calculate the Reynolds number corresponding to the node. : 。 6. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 5, characterized in that, S2 includes, S2.1, let... For node indexing, use the corresponding node and The empirical formula is used to calculate the first Initial drag coefficient of each node ; Let the first Each node drag coefficient ,right Perform a Taylor expansion: ； In the formula, for The drag coefficient at that time The function equals The values ​​of derivatives at each order; set up yes The influence coefficient, let ,based on The even function property, let Based on the symmetry of the cable segments, ; Definition of the first Each node Contribution to the adaptive correction term : ； Definition of the first Each node Contribution to the adaptive correction term : ； In the formula, for The influence coefficient; Using the first The corresponding nodes and Calculate the adaptive correction term : ； use and Calculate the first Resistance coefficient at each node : 。 7. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 6, characterized in that, S2 includes S2.2, after the attitude and position of the nodes are updated, the Reynolds number and angle of attack of each node are recalculated, and the drag coefficient of each node is updated synchronously based on the updated Reynolds number and angle of attack. Introducing the mixing coefficient The updated drag coefficient is: ； In the formula, For the first The drag coefficient after the next iteration For the first The drag coefficient after the next iteration As the reference drag coefficient, This is a correction term for the drag coefficient.

8. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 7, characterized in that, S2 includes S2.3, calculating the hydrodynamic forces acting on the nodes using the updated drag coefficient. : ； In the formula, For direction variables, , The direction is east. North direction Vertical The density of water, For the node perpendicular to Cross-sectional area in the direction, for The velocity component in the direction.

9. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 8, characterized in that, S2 includes S2.4, establishing a northeast-northeast coordinate system with the nodes as the origin, and establishing triaxial force equilibrium equations for each node: ； ； ； In the formula, To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics To act on the first Nodes Directional hydrodynamics For the first The cable segment at the first node facing the bottom of the underwater mooring is paired with the first... The tension applied at each node, For the first The cable segment at the first node facing the top of the underwater mooring is paired with the first... The tension applied at each node, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first The section of cable in the Above the node, relative to the node with respect to the first node In the northeast celestial coordinate system established with nodes as the origin The deflection angle of the axis, For the first Buoyancy at each node; Solving the triaxial force equilibrium equations yields the tension in the cable segment. Spatial geometric direction of cable segment This leads to the derivation of the node's three-dimensional coordinates. .

10. The method for calculating the hydrodynamics of underwater mooring based on an adaptive drag coefficient according to claim 9, characterized in that, S3 includes setting a convergence condition: the change in force on a node is less than a preset threshold for the change in force between two adjacent iterations. Or, the change in drag coefficient between two consecutive iterations is less than a preset threshold for the change in drag coefficient. ; Substitute the updated hydrodynamics into the triaxial force balance equation, repeat steps S1 to S2 until the convergence condition is met, and output the hydrodynamic response results of the moored buoy. The hydrodynamic response results of the moored buoy include the attitudes of each node of the moored buoy after convergence. Cable tension distribution after convergence at each node The overall hydrodynamic response results after convergence, including the drag coefficients of each node after convergence. Hydrodynamics of each node after convergence The displacement of the buoy after convergence and the shape of the cable after convergence; The value after convergence. For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Axis coordinates For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics For the first After convergence of nodes Directional hydrodynamics.

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