A method for maintaining the volume of aquaculture cages based on annular support structure

Abstract

The present invention discloses a method for maintaining the volume of an aquaculture cage based on an annular support structure, which relates to the technical field of cage volume maintenance. The method comprises the following steps: inputting cage parameters, initializing the support ring spacing and support ring diameter; obtaining the maximum deformation of the net by calculating the fluid load and net tension; judging whether the maximum deformation of the net satisfies the deformation constraint, and calculating the number of support rings based on the support ring spacing and cage height; determining the cable system design parameters, and verifying and iterating the cable system design parameters, thereby achieving the dynamic stability and volume retention capability of the cage under complex sea conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of cage volume maintenance, and in particular to a method for maintaining the volume of an aquaculture cage based on an annular support structure. Background Art

[0002] At present, research on cage volume maintenance rates at home and abroad is still in its early stages, with the focus mainly on improving traditional counterweight systems. For example, simply increasing the bottom counterweight mass and optimizing the distribution of the counterweights. However, these methods will still cause the cages to deform significantly under strong currents or large waves, and the actual volume maintenance efficiency is low, making it impossible to fundamentally maintain the designed volume shape. In addition, the increase in counterweight mass requires the auxiliary frame system to provide sufficient buoyancy, which will increase the overall load of the cage and increase construction costs. The current technical system has not yet established a complete set of cage volume maintenance theories and methods, and breakthrough technological innovations are urgently needed to solve this key technical bottleneck that restricts the development of deep-sea aquaculture.

[0003] The present invention mainly provides a method for maintaining the volume of an offshore aquaculture cage, aiming to significantly improve the structural stability and volume retention capacity of the cage in a complex marine environment. Gravity cages generally suffer from excessive deformation of the net system under the combined action of dynamic loads such as waves and currents. This deformation phenomenon causes a significant decrease in the effective aquaculture volume ratio of the cage, changes the activity space and swimming behavior patterns of farmed fish, directly affects the fish farming density and growth efficiency, and seriously affects the economic benefits of aquaculture. Especially during extreme sea conditions such as typhoons, the large deformation of the cage may also cause safety problems such as net rupture and structural failure. Summary of the Invention

[0004] In view of the above situation, the present invention discloses a method for maintaining the volume of aquaculture cages based on an annular support structure, comprising the following steps:

[0005] S1: Input the cage parameters and initialize the support ring spacing and support ring diameter;

[0006] S2. Calculate the fluid load and mesh tension to obtain the maximum deformation of the mesh;

[0007] S3, determining whether the maximum deformation of the net meets the deformation constraint. If not, adjust the support ring spacing and support ring diameter, and return to step S2; if the deformation constraint is met, proceed to step S4;

[0008] S4. Calculate the number of support rings based on the support ring spacing and cage height;

[0009] S5. Determine the cable system design parameters, and verify and iterate the cable system design parameters.

[0010] In a preferred embodiment, in step 2, the maximum deformation of the net is calculated. :

[0011] ;

[0012] Among them, F d is the fluid load, T is the mesh tension, is the support ring spacing.

[0013] In a preferred embodiment, in step 3,

[0014] if , go to step S4,

[0015] Among them, D s is the diameter of the support ring, D is the diameter of the cage, and Δ is the safety margin;

[0016] if , then reduce the support ring spacing Δh, recalculate the maximum deformation δ of the net; increase the support ring diameter D s , re-judge whether the maximum deformation of the mesh meets the deformation constraint.

[0017] In a preferred embodiment, in step 4, the number of support rings n is calculated based on the support ring spacing Δh and the cage height H:

[0018] .

[0019] In a preferred embodiment, the cable system design parameters include the number of cables and the cable elastic modulus. The cable system design parameters are verified and iterated. If the cable system design parameters do not meet the cable constraint conditions, the support ring spacing Δh or the support ring diameter D is adjusted. s , recalculate the maximum deformation of the net δ, the number of support rings n, the number of cables m and the cable elastic modulus E c , until all deformation constraints and cable constraints are met.

[0020] In a preferred embodiment, the tension of a single cable is T c , For the angle between the cable and the horizontal plane, construct the equilibrium equation:

[0021] Vertical balance: mT c sinθ=W;

[0022] Horizontal balance: mT c cosθ=F support ;

[0023] Where W is the weight of the support ring, F support For support force;

[0024] Based on the equilibrium equation, the number of cables m is determined.

[0025] In a preferred embodiment, the tension T of a single cable is c and allowable elongation ΔL c , calculate the cable elastic modulus E c :

[0026] ;

[0027] Among them, A c is the cross-sectional area of ​​the cable, L c is the cable length.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] This invention develops a cage volume maintenance method that achieves dynamic stability and volume retention in complex sea conditions by installing a multi-stage annular support structure around the cage. Using a parametric design approach, the number, spacing, and cable configuration of support rings can be optimized based on the cage specifications (diameter, height), net characteristics (material, mesh size), and actual marine conditions (current velocity, wave height), ensuring the cage maintains an effective aquaculture volume.

[0030] Annular support rings are layered at different heights within the cages, securing the cables to the nets to form a three-dimensional support system. By adjusting the spacing Δh between the support rings and the number of cables m, the maximum net deformation δ is actively controlled, dynamically optimizing the aquaculture volume.

[0031] Through the coordinated design of layered annular support rings and high-strength cables, the structural stability and volume retention capacity of the cages in complex marine environments such as waves and currents can be greatly improved, effectively solving the problem of aquaculture volume loss caused by excessive deformation of the net.

[0032] The innovative three-dimensional support structure can evenly disperse dynamic loads and prevent local stress concentration. At the same time, parametric design allows for adaptive adjustment of the support system, which can not only adapt to different sea conditions but also reduce maintenance costs. While increasing aquaculture density and economic benefits, it also enhances the safety and durability of the cages in extreme weather conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the overall structure of the offshore aquaculture cage;

[0034] Figure 2 This is an overhead view of offshore aquaculture cages.

[0035] 1: Ring support structure; 2: Cable; 3: Net. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The fully parametric design concept of the marine aquaculture cage volume maintenance system of the present invention is: when the cage parameters, such as cage height, diameter, mesh diameter, mesh length, mesh axial stiffness, etc., are determined, then the support ring diameter, support ring spacing, number of cables, and cable axial stiffness are a process that affects each other.

[0038] Example 1

[0039] Specific design methods

[0040] 1. Deformation analysis of net under uniform flow

[0041] (1) Fluid load calculation

[0042] There is a direct relationship between the degree of deformation of the mesh and the fluid load it is subjected to. The fluid load is the core consideration in the design of the volume maintenance device.

[0043] When seawater flows through the net cage, the water flow will produce a continuous fluid load on the surface of the net. The size and distribution of this load directly determine the deformation characteristics of the net.

[0044] The fluid load per unit area on the mesh in uniform flow for:

[0045] ;

[0046] in, : seawater density; : drag coefficient of the net; : Flow velocity (m / s).

[0047] (2) Elastic deformation of the net

[0048] There's a direct and tight coupling between net deformation and the diameter of the support rings, a relationship that directly impacts the structural safety and aquaculture efficiency of the entire cage system. The degree of net deformation under flow loads determines the minimum allowable diameter of the support rings, which in turn constrains the maximum possible net deformation. These two constraints require calculation to achieve an optimal balance.

[0049] Specifically, the amount of deformation of the net directly determines the amount of space required for the support ring. If the net deforms significantly under flow loads, the diameter of the support ring must be increased accordingly to ensure that the deformed net does not contact the support ring. Once the net and the support ring come into contact, not only will the net material wear out, shortening its service life, but it may also cause localized stress concentration, increasing the risk of structural failure. Especially in extreme sea conditions such as typhoons, such contact can cause the net to rupture or the support ring to deform, posing a serious safety hazard.

[0050] ① Basic assumptions

[0051] The net is approximately an elastic film, which is affected by uniform flow and produces lateral deformation.

[0052] The net tension T is evenly distributed along the net (neglecting local stress concentration).

[0053] The maximum deformation δ is smaller than the support ring spacing Δh, so the small deformation theory can be used.

[0054] Fluid load F d Evenly distributed on the mesh.

[0055] ② Mechanical balance analysis

[0056] Considering a micro-segment of the mesh between the support rings, the force analysis is as follows:

[0057] Fluid load per unit area F d :

[0058] ;

[0059] Net tension T along the tangential direction of the net: Assume that the initial tension of the net remains approximately constant after deformation, and ignore elastic elongation.

[0060] Assuming the spacing between the support rings is Δh, the shape of the net after deformation is approximately parabolic, and the deformation curve y(x) is:

[0061] ;

[0062] y is the position of the mesh after deformation, and x is the vertical coordinate position.

[0063] ③ Differential equation of deformation curve

[0064] Take the mesh micro-segment dx, analyze the force, and find the component of tension T in the y direction for:

[0065] ;

[0066] Among them, when the angle When the minimum time: ;

[0067] Construct the balanced equation:

[0068] ;

[0069] Right now:

[0070] ;

[0071] eliminate The final equilibrium equation is obtained:

[0072] ;

[0073] ④ Solve the parabolic deformation curve

[0074] Solve the balanced equation:

[0075] ;

[0076] integral:

[0077] ;

[0078] By symmetry, The slope is , so .

[0079] Integrate again:

[0080] ;

[0081] 、 is the integration constant.

[0082] Boundary conditions: hour, :

[0083] ;

[0084] Maximum deformation Occurs in :

[0085] ;

[0086] Take the absolute value:

[0087] ;

[0088] in: is the fluid load, is the support ring spacing, For the tension of the net.

[0089] (3) Calculation of net tension

[0090] The relationship between strain and tension of the network cable is based on Hooke's law. and strain The relationship is:

[0091] ;

[0092] in: is the elastic modulus of the network cable; For strain, is the elongation, is the original length, is the cross-sectional area of ​​the network cable:

[0093] ;

[0094] Therefore, the tension of the network cable :

[0095] ;

[0096] The net tension T depends on the elastic modulus E of the wire, the wire diameter d, the original length L, and the initial preload T0:

[0097] ;

[0098] 2. Support ring parameter design

[0099] (1) Support ring diameter D s

[0100] The diameter of the support ring affects the deformation behavior of the net. While a larger ring diameter provides greater deformation tolerance, it also increases the overall load and material cost of the system. Therefore, the ring diameter should be optimized to ensure that the net does not contact the net, balancing structural safety and cost-effectiveness.

[0101] In order to prevent the net from touching the support ring after deformation and causing friction, the support ring diameter D s Must meet:

[0102] ;

[0103] Wherein, D is the diameter of the cage; is the maximum deformation of the mesh between the support rings; Δ is the safety margin.

[0104] (2) Support ring spacing Δh

[0105] The spacing between support rings is a key design parameter affecting the deformation characteristics of a net. The distance between adjacent support rings directly determines the net's deformation range under fluid loads. When the spacing between support rings is larger, the net's free span between support points increases, resulting in more significant deformation under the same flow.

[0106] Therefore, the spacing Δh between the support rings should ensure the maximum deformation of the mesh between the support rings. Not exceeding the allowed value:

[0107] ;

[0108] The maximum deformation of the net .

[0109] (3) Number of support rings n

[0110] ;

[0111] Where H is the height of the cage.

[0112] 3. Cable system design

[0113] (1) Number of cables (m)

[0114] The cables are evenly distributed around the support ring. The number of cables m depends on the support force required:

[0115] ;

[0116] in, The total support force provided to the support ring; is the tension of a single cable; is the angle between the cable and the horizontal plane (affected by the gravity of the support ring).

[0117] After the number of cables m is determined, the spacing between cables It is then determined that:

[0118] ;

[0119] (2) Number of cables m and cable tension T c

[0120] The weight W of the support ring is balanced by the vertical component of the cable:

[0121] ;

[0122] ;

[0123] in: is the support ring density, is the volume of the support ring, is the acceleration due to gravity.

[0124] (3) Cable elastic modulus E c

[0125] The elastic modulus E of the cable c Should meet the following requirements:

[0126] ;

[0127] in: is the cross-sectional area of ​​the cable; is the cable elongation; is the original length of the cable (depending on the diameter of the support ring D s )

[0128] Example 2

[0129] Specific design process

[0130] S1. Input the cage parameters and initialize the support ring spacing and support ring diameter.

[0131] Input the cage parameters, such as cage height, diameter, wire diameter, mesh length, wire axial stiffness, etc.

[0132] Initialize the support ring spacing Δh;

[0133] Initialize the support ring diameter D s =D+2Δ.

[0134] S2. By calculating the fluid load and mesh tension, the maximum deformation δ of the mesh is obtained.

[0135] S21. Calculate fluid load F d :

[0136] ;

[0137] S22. Calculate the net tension T:

[0138] The initial assumption is T=T0.

[0139] If the network cable parameters are known, use the formula Correction.

[0140] S23. Calculate the maximum deformation of the net:

[0141] ;

[0142] S3. Determine whether the maximum deformation of the net meets the deformation constraint condition.

[0143] if , enter S4.

[0144] if ,but:

[0145] Reduce the support ring spacing Δh and recalculate the maximum deformation δ of the mesh.

[0146] Increase the support ring diameter D s , re-judge whether the maximum deformation of the mesh meets the deformation constraint.

[0147] S4: Calculate the number n of support rings based on the support ring spacing Δh and the cage height H.

[0148] ;

[0149] S5: Determine the cable system design parameters, and verify and iterate the cable system design parameters.

[0150] S51. Calculate the weight W of the support ring:

[0151] ;

[0152] in: is the support ring density, is the volume of the support ring, and g is the acceleration due to gravity.

[0153] S52. Determine the number of cables m based on the gravity of the support ring:

[0154] Assume that the tension of a single cable is T c , For the angle between the cable and the horizontal plane, construct the equilibrium equation:

[0155] Vertical balance: mT c sinθ=W;

[0156] Horizontal balance: mT c cosθ=F support；

[0157] Among them, F support The horizontal force provided by the cable should be equal to the horizontal fluid load F d Equal, so as to ensure that the support ring remains balanced in the horizontal direction.

[0158] Based on the above equilibrium equation, determine the number of cables m.

[0159] S53. Select the cable elastic modulus E c :

[0160] According to the single cable tension T c and allowable elongation ΔL c , calculate E c :

[0161] ;

[0162] Among them, A c is the cross-sectional area of ​​the cable, L c is the cable length.

[0163] Verify and iterate the cable system design parameters.

[0164] If the cable system design parameters do not meet the cable constraints, for example, m is too large or the elastic modulus is E c If the material does not exist, adjust the support ring spacing Δh or the support ring diameter D s , recalculate δ, n, m, E c Repeat until all deformation constraints and cable constraints are met.

[0165] Example 3

[0166] Parameter coupling relationship analysis

[0167] In the design of the support ring system of the offshore aquaculture cage, the diameter of the support ring D s , support ring spacing Δh, the number of support rings n, and the number of cables m and other key parameters constitute a highly coupled mechanical system. The various parameters influence and restrict each other, and need to be coordinated and optimized through a systematic approach.

[0168] (1) Support ring diameter D s

[0169] Directly affected by the maximum deformation of the net, δ, it must satisfy D s >D+2δ+Δ, otherwise the net may touch the support ring and cause structural failure. Increase D s Will increase the weight of the support ring W, thereby increasing the cable tension T c Depending on the requirements, it may be necessary to adjust the number of cables m or the material strength.

[0170] (2) Support ring spacing Δh

[0171] Smaller spacing reduces the maximum mesh deformation δ, but this increases the number of support rings n, increasing cost and installation complexity. Deformation control and economic efficiency must be balanced, and the optimal Δh must be determined through iterative calculations.

[0172] (3) Number of support rings n

[0173] Determined by the support ring spacing Δh and the cage height H ( ).

[0174] (4) Number of cables (m)

[0175] Need to balance the support ring gravity W and cable tension T cIncreasing m can disperse the load, but it will increase the difficulty of installation and needs to be combined with the support ring diameter D s Design a reasonable layout.

[0176] The design of the support ring system is a multi-objective optimization problem that requires a comprehensive consideration of mechanical performance, economics, and construction feasibility. Table 1 shows a parameter sensitivity analysis, which was used to find the optimal solution.

[0177] Table 1 Parameter sensitivity analysis:

[0178]

[0179] The cage volume maintenance method based on the annular support structure of the present invention effectively improves the structural stability and volume retention capacity of the cage under the action of waves and currents by arranging a series of annular support rings at different heights of the cage and combining them with high-strength cables and nets for coordinated fixation. Specifically, the support rings are evenly distributed in layers along the depth direction of the cage and are tightly connected to the net through an optimized cable system to form a three-dimensional spatial support structure. When the cage is impacted by waves and currents, the cage can still maintain a shape similar to its original design in a wave and current environment. This structure not only significantly improves the cage's ability to resist deformation, but can also adapt to different sea conditions by adjusting the spacing between support rings and cables, ensuring efficient use of aquaculture space.

[0180] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. The embodiments should therefore be considered illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for maintaining the volume of aquaculture cages based on an annular support structure, characterized in that: The steps include: S1: Input the cage parameters and initialize the support ring spacing and support ring diameter; S2. Calculate the fluid load and mesh tension to obtain the maximum deformation of the mesh; S3, determining whether the maximum deformation of the net meets the deformation constraint condition. If not, adjust the support ring spacing and support ring diameter, and return to step S2; if the deformation constraint condition is met, proceed to step S4; S4. Calculating the number of support rings based on the support ring spacing and cage height; S5. Determine the cable system design parameters, and verify and iterate the cable system design parameters; The cable system design parameters include the number of cables and the cable elastic modulus, and the cable system design parameters are verified and iterated; The verification and iteration process is as follows: Preliminarily determine the design parameters of the cable system and verify whether they meet the constraints. If not, adjust the support ring spacing Δh or the support ring diameter D s , recalculate the maximum deformation of the net δ, the number of support rings n, the number of cables m and the cable elastic modulus E c , and the iterative process is repeated until all deformation constraints and cable constraints are met.

2. The method for maintaining the volume of aquaculture cages based on an annular support structure according to claim 1, characterized in that: In step 2, the maximum deformation δ of the net is calculated: Among them, F d is the fluid load, T is the mesh tension, and Δh is the support ring spacing.

3. The method for maintaining the volume of aquaculture cages based on an annular support structure according to claim 2, characterized in that: In the step 3, if Go to step S4, Among them, D s is the diameter of the support ring, D is the diameter of the cage, and Δ is the safety margin; if Then reduce the support ring spacing Δh, recalculate the maximum deformation δ of the net; increase the support ring diameter D s , re-judge whether the maximum deformation of the mesh meets the deformation constraint conditions.

4. The method for maintaining the volume of aquaculture cages based on an annular support structure according to claim 1, characterized in that: In step 4, the number of support rings n is calculated based on the support ring spacing Δh and the cage height H:

5. The method for maintaining the volume of aquaculture cages based on an annular support structure according to claim 1, characterized in that: Assume that the tension of a single cable is T c , θ is the angle between the cable and the horizontal plane, and the equilibrium equation is constructed: Vertical balance: mT c sinθ=W; Horizontal balance: mT c cosθ=F support ; Where W is the weight of the support ring, F support For support force; Based on the equilibrium equation, the number of cables m is determined.

6. The method for maintaining the volume of aquaculture cages based on an annular support structure according to claim 1, characterized in that: According to the single cable tension T c and allowable elongation ΔL c , calculate the cable elastic modulus E c : Among them, A c is the cross-sectional area of ​​the cable, L c is the cable length.

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