Drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer structure and design method

Abstract

This invention belongs to the field of drag-reducing, wear-resistant, and antifouling composite functional surface technology, specifically disclosing a drag-reducing, antifouling, and wear-resistant composite biomimetic surface layer, its structure, and design method. It effectively solves the current problem of a lack of synergistic drag-reducing, antifouling, and wear-resistant functional surface technology for ship hulls. The design method includes: (1) simplifying the surface texture of the clam shell into triangular grooves; (2) tilting the direction of the triangular grooves by 45° and then rotating them by 90° to form interlaced fence-shaped composite grooves. The composite biomimetic surface layer structure is a fence-shaped composite groove based on triangular grooves combined with the scute scale grooves of shark skin. The composite biomimetic surface layer is applied to the surface of the ship hull. This invention is beneficial for energy saving and consumption reduction in water flow, inhibiting marine biofouling, and solving the durability problem caused by sandy water flow impact and wear. It is a green and environmentally friendly antifouling and drag-reducing biomimetic design scheme.

Description

Technical Field

[0001] This invention belongs to the field of drag-reducing, wear-resistant, and anti-fouling composite functional surface technology, and particularly relates to a drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer structure and design method. Background Technology

[0002] Surface friction resistance accounts for approximately 50% of the total resistance of low- and medium-speed ships, while this proportion can reach 70% for submarines. When a ship is stationary or traveling at low speeds, its hull surface is highly susceptible to marine organisms, including a wide variety of species such as algae, shellfish, and mollusks. These organisms form complex communities on the hull surface, easily causing fouling, corrosion, and weight gain, leading to a significant increase in hull resistance, reduced speed, and increased energy consumption. This increases the risk of equipment failure and the frequency of maintenance, resulting in substantial economic losses and hindering the ship's operational performance. Therefore, synergistic drag reduction and fouling prevention can significantly reduce ship energy consumption, decrease the frequency of maintenance and cleaning, and improve economic efficiency.

[0003] Chinese invention patent CN117521369A discloses a flexible biomimetic drag-reducing mold based on the scute groove structure of shark skin, including a substrate and rib holes on the substrate. Numerical simulations show a drag reduction rate of 12% at an inlet flow velocity of 3 m / s. However, this study does not consider anti-fouling functionality. Chinese invention patent CN109625154A discloses a biomimetic microcavity drag-reducing structure. This structure is a microcavity array on the substrate surface, arranged in a feather-like array, with mushroom-shaped structures at the top of the gaps between adjacent microcavities. This patent suggests that a ship hull using this biomimetic microcavity structure can achieve hydrophobic and drag-reducing effects. However, this study does not consider anti-fouling functionality. Chinese invention patent CN114160108A discloses a biomimetic porous mesh composite material for oil collection and drag reduction on ship hull surfaces. This material uses a stainless steel mesh soaked in ethanol as a supporting substrate, then sprays a mixed solution of modified silica and other materials and dries it. A porous mesh-like micro / nano structure, modeled after the Red-necked Swallowtail butterfly, has been created. This structure possesses oleophilic and hydrophobic properties, which could help reduce water resistance in water or oil-water mixtures. However, the structure is highly complex, and its antifouling properties have not yet been investigated.

[0004] In summary, most existing research focuses on biomimetic microgroove coatings, surface structures, and flexible films to reduce frictional resistance in ship hulls. However, these technologies suffer from the following problems: (1) Shark and dolphin skin has micro-nano structures and secretes mucus to inhibit microbial adhesion and rapid swimming, which is inconsistent with the actual working conditions of ships. (2) Coatings on the hull surface are prone to local wear and failure under continuous water flow, failing to achieve the expected drag reduction effect; changes in working conditions during ship navigation and berthing over a period of time can easily lead to severe biofouling. (3) Current technologies rarely consider the comprehensive performance of hull drag reduction, antifouling, and wear resistance. Therefore, there is an urgent need to propose effective surface technologies for synergistic drag reduction, antifouling, and wear resistance for ship hulls. Summary of the Invention

[0005] One objective of this invention is to provide a design method for a composite biomimetic surface layer structure that reduces drag, prevents fouling, and is wear-resistant, effectively solving the current problem of the lack of synergistic drag-reducing, fouling-resistant, and wear-resistant functional surface technologies for ship hulls.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a design method for a composite biomimetic surface layer structure with drag reduction, anti-fouling and wear resistance, including the following steps: S1, simplifying the surface texture of the mirror clam into triangular grooves; S2, tilting the direction of the triangular grooves by 45° and then rotating them by 90° to form an interlaced fence-shaped composite groove.

[0007] Furthermore, the width-to-depth ratio of the triangular trench is s / h = 1, where s represents the width of the triangular trench and h represents the depth of the triangular trench; in the fence-shaped composite trench, the spacing b between adjacent triangular trenches is b = 2s.

[0008] Furthermore, the width of the triangular groove ranges from 0.1 mm to 0.2 mm.

[0009] Another objective of this invention is to provide a drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer structure, designed using the design method described in the above embodiments.

[0010] Furthermore, the composite biomimetic surface layer structure is a fence-shaped composite groove based on triangular grooves combined with the shield-scale grooves of shark skin.

[0011] Another objective of this invention is to provide a drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer, made of resin-based composite material, and applied to the surface of a ship hull. The composite biomimetic surface layer has the structure described in the above embodiments.

[0012] Furthermore, the composite biomimetic surface layer is adhered to the ship's waterline, the bottom of the ship, and the hull surface near the propeller, which are prone to biofouling.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The present invention provides a composite biomimetic surface layer with a fence-shaped composite groove structure, which combines the main features of the microstructure of the surface of the mirror clam and the surface of the shark. It has the characteristics of drag reduction, wear resistance and inhibition of marine fouling organism attachment. It is beneficial to the energy saving and consumption reduction of the ship in the water flow, the inhibition of marine biological fouling and the solution of the durability problem caused by the impact and wear of sandy water flow. It is a green and environmentally friendly anti-fouling and drag reduction biomimetic design scheme.

[0014] (2) The composite bionic surface layer of the present invention is made of resin composite material. It can be flexibly set on the surface of the ship by means of easy replacement such as pasting. At the same time, it can be flexibly prepared according to the actual length of the ship, draft and other parameters. When it ages, it can be replaced by a new composite bionic surface layer through dry dock maintenance. It is easy to operate and saves time and effort. Attached Figure Description

[0015] Figure 1 This is a three-dimensional image of a biomimetic sample with triangular grooves on the surface of the biomimetic microgroove.

[0016] Figure 2 This is a three-dimensional image of a biomimetic sample with a semi-circular groove surface.

[0017] Figure 3 This is a three-dimensional image of a biomimetic sample with a fence-shaped composite groove surface.

[0018] Figure 4 The graph shows the drag reduction results for each simulation model in Experiment Example 2.

[0019] Figure 5 This is a graph showing the drag reduction results of the fence-shaped composite trench and the triangular trench at different flow velocities in Experiment Example 2.

[0020] Figure 6 This is a graph showing the drag reduction results of the biomimetic surface layer near the waterline of the two-dimensional hull in Experiment Example 3. Detailed Implementation

[0021] Example 1: A design method for a drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer structure, comprising the following steps: S1, simplifying the surface texture of the clam into triangular grooves; S2, simplifying the dermal grooves on the surface of shark skin into a 45-degree interlaced grid. However, since the shape of a single dermal scale is too complex, the orientation of the triangular grooves in step S1 is tilted by 45° and then rotated by 90° to form an interlaced fence-shaped composite groove.

[0022] The width-to-depth ratio of the triangular trench is s / h = 1. In the fence-shaped composite trench, the spacing b between adjacent triangular trenches is b = 2s. Wherein, s represents the width of the triangular trench, and the value of s ranges from 0.1mm to 0.2mm; h represents the depth of the triangular trench.

[0023] The composite biomimetic surface layer structure in this embodiment is a fence-shaped composite groove based on triangular grooves combined with the shield scale structure of shark skin. The triangular grooves are based on the surface texture of a mirror clam, ultimately forming a fence-shaped composite groove.

[0024] The composite biomimetic surface layer with the fence-shaped composite groove of this embodiment is made of resin composite material and can be flexibly installed on the hull surface by means of easy replacement such as pasting, especially in areas near the waterline of the ship that are prone to biofouling, in areas where the bottom of the ship is easily worn, and on the hull near the propeller.

[0025] Since the attachment and reproduction of large algae and marine organisms is one of the main causes of biofouling on ship hulls, and the microbial mucus produced by diatoms and other organisms provides the necessary conditions for further attachment and reproduction, and diatoms usually attach to grooved surfaces larger than themselves, the applicant's research found that the microscopic raised textures on the surface of the mirror clam are smaller than the size of diatoms, making them less susceptible to diatom attachment. Therefore, this application combines the main characteristics of the microstructure of the mirror clam surface and shark skin surface, and uses resin-based composite materials to create a composite biomimetic surface layer, which combines drag reduction, wear resistance, and inhibition of marine fouling biofouling. The structural design considers the comprehensive performance of microgrooves in reducing drag, resisting wear and corrosion, and inhibiting marine biofouling. By inhibiting or making it difficult for marine organisms to form slime attachment, the biofouling on the ship hull surface is greatly reduced, thus reducing biofouling, fouling, and corrosion.

[0026] Experimental Example 1: Verification of the wear resistance of composite biomimetic surface layer.

[0027] The following three types of biomimetic microgroove surfaces were used: triangular groove, semi-circular groove and fence-shaped composite groove of Example 1. After modeling, resin materials were 3D printed to prepare biomimetic samples respectively.

[0028] The 3D model dimensions of each biomimetic sample are 20mm × 10mm × 2mm. The surface structures of the three biomimetic microgrooves are as follows: Figure 1 , Figure 2 and Figure 3 As shown in Table 1, the main dimensional parameters of the triangular and fence-shaped composite trenches are shown in Table 1; the diameter d of the semi-circular trench is d = 1 mm, d / h′ = 1, where h′ represents the depth of the semi-circular trench, and the number of semi-circular trenches is 5.

[0029] Table 1. Dimensional parameters of triangular trenches and fence-shaped composite trenches

[0030] type s(mm) h(mm) s / h Number of grooves triangular groove 1.6 1.6 1 6 Fence-shaped composite trench 1.6 1.6 1 4

[0031] Erosion experiments were conducted on different biomimetic sample pads using quartz sand with an average particle size of 100 μm and a concentration of 12.5%.

[0032] The specific experimental method is as follows: (1) A multiphase flow erosion corrosion tester was used to conduct sand-containing water flow impact wear tests at various impact angles on 45# carbon steel samples without attached biomimetic samples, 45# carbon steel samples with attached biomimetic samples with triangular grooves on the surface of the test surface, 45# carbon steel samples with attached biomimetic samples with grid-shaped composite grooves on the surface of the test surface, and 45# carbon steel samples with attached biomimetic samples with semi-circular grooves on the surface of the test surface. The impact angle settings in the multiphase flow erosion corrosion tester include 0°, 30°, 45°, 60° and 90°.

[0033] (2) After the test, the mass loss rate of different 45# carbon steel samples was measured by weighing.

[0034] A positive mass loss rate, especially a smaller value, indicates better wear resistance of the biomimetic specimen. A negative mass loss rate indicates weight gain due to corrosion and rust on the back of the 45# carbon steel specimen without the biomimetic specimen attached. Test results showed that all three biomimetic specimens exhibited significant wear resistance at a sand concentration of 12.5%. Table 2 shows the average and maximum mass loss rates at various impact angles. Overall, the triangular groove and fence-shaped composite groove surface layers showed better wear resistance than the semi-circular groove surface layer.

[0035] Table 2. Abrasion resistance test results of smooth surface and different biomimetic sample surface layers on 45# carbon steel specimens.

[0036] Quality loss rate (%) Smooth sample semi-circular groove triangular groove Fence-shaped composite trench average value 0.145 0.014 0.027 0.023 Maximum value 0.152 0.069 0.039 0.037

[0037] Experimental Example 2: Verification of drag reduction performance of composite biomimetic surface layer.

[0038] Five biomimetic microgroove surface simulation models were established: triangular groove, trapezoidal groove, knife-edge groove, semi-circular groove, and the fence-shaped composite groove of Example 1. Then, CFD numerical methods were used to simulate the drag reduction effect of different simulation models in water flow. The lower wall of the simulated flow field was a microgroove, and the upper wall was a smooth surface.

[0039] The frictional resistance coefficients near the upper and lower walls can be obtained through numerical simulation. A drag reduction ratio is defined to compare the drag reduction effects of different biomimetic microgroove surfaces:

[0040]

[0041] Where η represents the drag reduction ratio. The coefficient of friction resistance of a smooth surface. F represents the frictional resistance coefficient of the microgroove surface. 平板 F represents the force acting on a smooth surface. 沟槽This represents the force acting on the surface of the microgroove.

[0042] The drag reduction ratio of each simulation model is as follows: Figure 4 As shown. Through numerical simulation of the flow field near the microgroove and prediction of drag reduction rate, it was estimated that when the water flow velocity is constant, the drag reduction rate of the fence-shaped composite groove, the knife-edge groove, and the triangular groove is higher than that of the trapezoidal groove and the semi-circular groove. Figure 4 While the blade-shaped groove surface also offers high drag reduction, this structure is unstable in water flow and susceptible to erosion and wear. In contrast, triangular and fence-shaped groove structures are more stable. The fence-shaped composite groove, a biomimetic surface created by combining two types of triangular grooves with different angles, exhibits the highest drag reduction rate within the simulated flow velocity range, averaging 9.29%. Figure 5 As shown.

[0043] Experimental Example 3: The effect of installing biomimetic surface layers at different locations on drag reduction and antifouling performance.

[0044] In reality, the main areas of marine fouling on ships are the underwater hull, near the waterline, and near the propeller. To focus on the impact of the installation location of the biomimetic surface layer on its drag reduction and antifouling effects, this experimental example models a triangular groove biomimetic surface layer installed on the hull surface to simplify the computational workload of the numerical simulation. Combining Experimental Examples 1 and 2, it is evident that the wear resistance and drag reduction performance of the triangular groove biomimetic surface layer are second only to the fence-shaped composite groove biomimetic surface layer in Example 1. Therefore, the selection of the triangular groove biomimetic surface layer for this experiment, while simplifying the computational workload of the numerical simulation, is a reliable reference.

[0045] This experimental example utilizes CAD software to create a two-dimensional smooth surface model of the hull, with a triangular grooved biomimetic surface layer placed at and near the waterline height T. Simulation results are shown below. Figure 6 The triangular groove biomimetic surface layer was applied to different locations on the hull surface, and the drag reduction rate was the highest when s / h = 1. The biomimetic surface layer installed near the waterline on the bow had a drag reduction effect, with the biomimetic surface layer installed at T-0.3T having the highest drag reduction rate. The biomimetic surface layer installed at the stern had a significant drag reduction effect at the propeller position and at a distance of T-0.2T from the waterline.

[0046] Further numerical simulations of the three-dimensional hull surface flow field yielded drag reduction rates, as shown in Table 3. Triangular grooved biomimetic surface layers (without propellers) were added at T-0.3T at the bow and T-0.2T at the stern, where T represents the distance from the waterline to the hull bottom. The drag reduction rate of these triangular grooved biomimetic surface layers at these locations was approximately 10%. In conclusion, the addition of biomimetic surface layers has a certain drag reduction effect.

[0047] Table 3. Drag reduction rate of the biomimetic surface layer near the waterline of the three-dimensional hull.

[0048] Guangshun Shipbuilding Bow T-0.3T At the stern, T-0.2T Resistance (N) 0.141 0.125 0.128 Drag reduction rate (%) 0 11.35 9.42

[0049] The above test examples demonstrate that the composite biomimetic surface layer with a fence-shaped composite groove provided by this invention can be applied to ship hulls and has effective drag reduction, wear resistance, and antifouling functions. Furthermore, the dimensions of the composite biomimetic surface layer provided by this invention can be prepared according to parameters such as the actual length and draft of the ship hull and then pasted onto different locations on the hull surface; when it ages, it can be replaced with a new composite biomimetic surface layer through dry-dock maintenance.

[0050] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A composite biomimetic surface layer structure for drag reduction, stain prevention, and wear resistance, characterized in that, The composite biomimetic surface layer structure is a fence-shaped composite groove based on triangular grooves combined with the scute scale grooves of shark skin. The design method for the composite biomimetic surface layer structure includes the following steps: S1. Simplify the surface texture of the clam shell into triangular grooves; S2. Tilt the direction of the triangular trench by 45° and then rotate it by 90° to form an interlaced fence-shaped composite trench. The width-to-depth ratio of the triangular groove is: ,in, Indicates the width of the triangular groove. The depth of the triangular groove is indicated; the width of the triangular groove ranges from 0.1 mm to 0.2 mm. In a fence-shaped composite trench, the spacing between adjacent triangular trenches : .

2. A drag-reducing, stain-resistant, and wear-resistant composite biomimetic surface layer, characterized in that, Made of resin-based composite material, it is applied to the surface of the ship hull, and the composite biomimetic surface layer has the composite biomimetic surface layer structure as described in claim 1.

3. The drag-reducing, anti-fouling, and wear-resistant composite biomimetic surface layer according to claim 2, characterized in that, Apply to areas prone to biofouling, such as the waterline, the bottom of the ship, and the hull surface near the propeller.

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