Anti-drag, antifouling and wear-resistant composite bionic surface layer structure and design method

Abstract

The invention belongs to the technical field of anti-drag, anti-fouling and anti-wear composite functional surfaces, and particularly discloses an anti-drag, anti-fouling and anti-wear composite bionic surface layer, a structure of the composite bionic surface layer and a design method of the composite bionic surface layer. The problem that a synergistic resistance-reducing, antifouling and wear-resisting functional surface technology for the ship body is lacked at present is effectively solved. The design method comprises the following steps: (1) simplifying the surface texture of the mirror clam into a triangular groove; and (2) inclining the trend of the triangular groove by 45 degrees, and then rotating by 90 degrees to form a staggered fence-shaped composite groove. The composite bionic surface layer structure is a fence-shaped composite groove which is based on a triangular groove and is combined with a placoid scale groove in the sharkskin surface. The composite bionic surface layer is arranged on the surface of the ship body. Energy conservation and consumption reduction of the ship body in the water flow are facilitated, marine organism fouling is inhibited, the durability problem caused by impact abrasion of the sand-containing water flow is solved, and an environment-friendly antifouling and drag-reducing bionic design scheme is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of drag reduction, wear resistance and anti-fouling composite functional surfaces, and particularly relates to a composite bionic surface layer structure with drag reduction, anti-fouling and wear resistance and a design method thereof. Background Technique

[0002] The surface friction resistance of medium and low-speed ships accounts for about 50% of the total hull resistance, and this proportion for submarines can reach 70%. When the hull surface is stationary or sailing at low speed, it is very easy to be attached by marine organisms, and there are a variety of organisms attached to the hull surface, including algae, as well as hard-shelled and soft-shelled animals. These organisms form a complex community structure on the hull surface, which is extremely easy to cause fouling, corrosion and weight gain of the ship surface, resulting in a sharp increase in the hull resistance, a decrease in the ship speed and an increase in energy consumption, increasing the risk of equipment failure and the number of repairs, with considerable economic losses and restricting the working performance of the ship at the same time. Therefore, collaborative drag reduction and anti-fouling can significantly reduce the energy consumption of ships, reduce the frequency of maintenance and cleaning, and improve economic benefits.

[0003] The Chinese invention patent with the publication number CN117521369A provides a flexible bionic drag reduction mold based on the placoid scale groove structure of the shark skin surface, including a substrate and rib holes on the substrate, and its numerical simulation result has a drag reduction rate of 12% when the inlet flow velocity is 3 m / s. However, the anti-fouling function is not considered in this research; the Chinese invention patent with the publication number CN109625154A discloses a bionic microcavity drag reduction structure, which is a microcavity array structure on the surface of the matrix, arranged in a feather-shaped array, and there is a mushroom-shaped structure at the top of the interval between adjacent microcavities. This patent believes that the ship hull with this bionic microcavity structure can form a hydrophobic and drag reduction effect. However, the anti-fouling function is not considered in this research; the Chinese invention patent with the publication number CN114160108A discloses an oil-collecting drag reduction bionic porous network composite material for the hull surface. This material uses a stainless steel mesh soaked in ethanol as the support substrate, and then sprays and dries a mixed solution such as modified silica. It imitates the porous network micro-nano structure of the red-necked birdwing butterfly and has the characteristics of lipophilic and hydrophobic, which is beneficial to improving the water resistance of ships in water or oil-water mixed media. However, this structure is very complex and the anti-fouling performance has not been studied.

[0004] In summary, most of the prior art research provides technologies that are beneficial for reducing the frictional resistance of the hull from the perspectives of bionic microgroove coatings, surface structures, and flexible membranes. These technologies have the following problems: (1) The skin surfaces of sharks and dolphins have micro-nano structures and secrete mucus by themselves to inhibit microbial attachment and enable rapid swimming, which does not conform to the actual working conditions of ships. (2) The coatings on the hull surface are prone to local wear and failure under continuous water flow scouring conditions, failing to achieve the expected drag reduction effect; the working conditions of ship navigation and docking for a certain period are likely to cause serious biofouling. (3) The current technologies rarely consider the comprehensive performance of hull drag reduction, antifouling, and wear resistance. Therefore, there is an urgent need to propose an effective surface technology with collaborative drag reduction, antifouling, and wear resistance functions for the hull. Summary of the Invention

[0005] An object of the present invention is to provide a design method for a drag reduction, antifouling, and wear-resistant composite bionic surface layer structure, effectively solving the problem of the current lack of surface technology with collaborative drag reduction, antifouling, and wear resistance functions for the hull.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a design method for a drag reduction, antifouling, and wear-resistant composite bionic surface layer structure, including the following steps: S1. Simplify the surface texture of the mirror clam into triangular grooves; S2. Tilt the direction of the triangular grooves by 45°, and then rotate by 90° to form an interlaced fence-shaped composite groove.

[0007] Further, the width-depth ratio of the triangular groove is: s / h = 1, where s represents the width of the triangular groove and h represents the depth of the triangular groove; in the fence-shaped composite groove, the spacing b between adjacent triangular grooves: b = 2s.

[0008] Further, the value range of the width of the triangular groove is 0.1 mm to 0.2 mm.

[0009] Another object of the present invention is to provide a drag reduction, antifouling, and wear-resistant composite bionic surface layer structure designed by using the design method described in the above embodiments.

[0010] Further, the composite bionic surface layer structure is a fence-shaped composite groove based on triangular grooves and simultaneously combined with the placoid scale grooves on the shark skin surface.

[0011] Another object of the present invention is to provide a drag reduction, antifouling, and wear-resistant composite bionic surface layer made of a resin-based composite material and provided on the hull surface, and the composite bionic surface layer has the structure described in the above embodiments.

[0012] Further, the composite bionic surface layer is pasted on the hull surface at the ship's waterline prone to biofouling, the bottom of the ship prone to wear, and near the propeller.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (1) The composite bionic surface layer with a structure of fence-shaped composite grooves provided by combining the main characteristics of the surface of Dosinia and the surface of shark has the characteristics of drag reduction, wear resistance and inhibition of marine fouling organism attachment, which is beneficial to energy conservation and consumption reduction of the hull in water flow, inhibition of marine organism fouling and solution of the durability problem caused by the impact wear of sediment-laden water flow. It is a green and environment-friendly anti-fouling and drag-reducing bionic design scheme.

[0014] (2) The composite bionic surface layer of the present invention is made of resin-based composite materials. It can be flexibly set on the hull surface by convenient replacement methods such as pasting. At the same time, it can be flexibly prepared according to parameters such as the actual length and draft of the hull. When it is aged in use, a new composite bionic surface layer can be replaced through docking maintenance, which is easy to operate, time-saving and labor-saving. Description of the Drawings

[0015] Figure 1 It is a three-dimensional view of a bionic specimen with a triangular groove on the bionic micro-groove surface.

[0016] Figure 2 It is a three-dimensional view of a bionic specimen with a semi-circular groove on the bionic micro-groove surface.

[0017] Figure 3 It is a three-dimensional view of a bionic specimen with a fence-shaped composite groove on the bionic micro-groove surface.

[0018] Figure 4 It is a graph of the drag reduction rate results of each simulation model in Test Example 2.

[0019] Figure 5 It is a graph of the drag reduction rate results of the fence-shaped composite groove and the triangular groove at different flow velocities in Test Example 2.

[0020] Figure 6 It is a graph of the drag reduction rate results of the bionic surface layer near the waterline of the two-dimensional hull in Test Example 3. Detailed Embodiments

[0021] Embodiment 1: A design method for a drag reduction, anti-fouling and wear-resistant composite bionic surface layer structure includes the following steps: S1. Simplify the surface texture of Dosinia into triangular grooves; S2. Simplify the dermal denticle grooves on the shark skin surface into a 45-degree staggered grid. However, due to the overly complex shape of a single dermal denticle, the orientation of the triangular grooves in step S1 is inclined by 45° and then rotated by 90° to form staggered fence-shaped composite grooves.

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

[0023] The composite bionic surface layer structure of this embodiment is a fence-shaped composite groove based on triangular grooves combined with the placoid scale structure on the shark skin surface. The triangular grooves are based on the surface texture of the mirror clam, and finally a fence-shaped composite groove is formed.

[0024] The composite bionic surface layer with the fence-shaped composite groove of this embodiment is made of a resin-based composite material and can be flexibly set on the hull surface in a convenient replacement way such as pasting, especially in the local area near the ship's waterline where biological fouling is likely to occur, the position on the ship bottom that is easily worn, and the hull near the propeller.

[0025] Since the attachment and reproduction of large algae and marine organisms are one of the main causes of hull biological fouling, and the microbial mucous membranes generated by diatoms and the like provide necessary conditions for the attachment and reproduction of more organisms, and diatoms usually attach to the surface of grooves larger than their own size. The applicant has found through research that the microscopic convex texture size on the surface of the mirror clam is smaller than the size of diatoms and is not easily attached by diatoms. Therefore, this application combines the main characteristics of the surface of the mirror clam and the micro-structure of the shark skin surface, and uses a resin-based composite material to make the composite bionic surface layer, so that it has the characteristics of drag reduction, wear resistance and inhibition of the attachment of marine fouling organisms. Considering the comprehensive performance of micro-groove drag reduction, wear resistance and inhibition of marine organism attachment in the structural design, and inhibiting or making it difficult for marine organisms to form mucus attachment on the material, and it is not easy for organisms to adsorb on the hull surface, which greatly reduces biological reproduction, fouling and corrosion.

[0026] Test Example 1: Verification of the wear resistance of the composite bionic surface layer.

[0027] The following three bionic micro-groove surfaces are used: triangular grooves, semi-circular grooves and the fence-shaped composite groove of Example 1. After modeling, resin materials are 3D printed to prepare bionic specimens respectively.

[0028] The 3D model sizes of each bionic specimen are all 20mm×10mm×2mm, and the three bionic micro-groove surface structures are as Figure 1 、 Figure 2 and Figure 3 shown. Among them, the main dimensional parameters of the triangular grooves and the fence-shaped composite grooves are shown in Table 1; the diameter d of the semi-circular grooves: d = 1mm, d / h' = 1, h' represents the depth of the semi-circular grooves, and the number of grooves of the semi-circular grooves is 5.

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

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

[0031] Erosion experiments on different bionic specimen cushions are carried out using quartz sand with an average particle size of 100μm and a concentration of 12.5%.

[0032] The specific experimental method is as follows: (1) Use a multiphase flow erosion-corrosion tester to conduct sand-laden water erosion wear tests on 45# carbon steel specimens without pasted bionic specimens, 45# carbon steel specimens with bionic specimens with triangular groove surface layers pasted on the surface to be tested, 45# carbon steel specimens with bionic specimens with fence-shaped composite groove surface layers pasted on the surface to be tested, and 45# carbon steel specimens with bionic specimens with semi-circular groove surface layers pasted on the surface to be tested at various impact angles. The impact angle settings in the multiphase flow erosion-corrosion tester include 0°, 30°, 45°, 60°, and 90°.

[0033] (2) After the test, use the weighing method to measure the mass loss rates of different 45# carbon steel specimens.

[0034] When the mass loss rate is positive and the value is smaller, it indicates that the wear resistance of the bionic specimen is better; when the mass loss rate is negative, it means that there is a weight gain on the back of the 45# carbon steel specimen without the pasted bionic specimen due to corrosion and rusting. According to the test results, when the sand concentration is 12.5%, all three bionic specimens have obvious wear resistance. The average value and maximum value of the mass loss rates at each impact angle are shown in Table 2. The wear resistance of the surface layers of triangular grooves and fence-shaped composite grooves is generally better than that of the semi-circular groove surface layer.

[0035] Table 2 Wear resistance test results of the smooth surface of 45# carbon steel specimens and the surface layers pasted with different bionic specimens

[0036] Mass loss rate (%) Polished specimen Semicircular groove Triangular groove Fence-shaped composite groove Average value 0.145 0.014 0.027 0.023 Maximum value 0.152 0.069 0.039 0.037

[0037] Test Example 2: Verification of the drag reduction performance of the composite bionic surface layer.

[0038] Establish the following five simulation models of bionic micro-groove surfaces: triangular grooves, trapezoidal grooves, blade-shaped grooves, semi-circular grooves, and the fence-shaped composite grooves of Example 1; then use the CFD numerical method to simulate the drag reduction effects of different simulation models in water flow. The lower wall surface of the simulated flow field domain is a micro-groove, and the upper wall surface is a smooth surface.

[0039] The magnitude of the friction drag coefficient near the upper and lower wall surfaces can be obtained through the numerical simulation results. Define the drag reduction rate to compare the drag reduction effects of different bionic micro-groove surfaces:

[0040]

[0041] Among them, η represents the drag reduction rate, represents the friction drag coefficient of the smooth surface, represents the friction drag coefficient of the micro-groove surface, F 平板 represents the force received by the smooth surface, F 沟槽Indicates the force acting on the micro-grooved surface.

[0042] The drag reduction rates of each simulation model are as Figure 4 shown. By conducting numerical simulations of the flow field near the micro-grooves and predicting the drag reduction rate, it is estimated that when the water flow velocity remains unchanged, the drag reduction rates of the fence-shaped composite groove, the blade-shaped groove, and the triangular groove are higher than those of the trapezoidal groove and the semi-circular groove; Figure 4 Although the drag reduction effect of the blade-shaped groove surface is also high, this structure is unstable in water flow and is not resistant to erosion and wear. In contrast, the triangular groove and the fence-shaped groove structures are more stable. The fence-shaped composite groove is a bionic surface obtained by cross-combining triangular grooves with two different inclinations. Within the simulated flow velocity range, its drag reduction rate is the highest, and the average drag reduction rate reaches 9.29%, as Figure 5 shown.

[0043] Experimental Example 3: Influence of installing the bionic surface layer at different positions on the hull on the drag reduction and anti-fouling effects.

[0044] In fact, the main parts of the ship where marine fouling organisms are likely to attach are the underwater part of the hull, the area near the waterline, and the area near the propeller. In order to focus on the influence of the installation position of the bionic surface layer on the effects such as drag reduction and anti-fouling, this experimental example models the installation of the triangular groove bionic surface layer on the hull surface to simplify the computational workload of the numerical simulation. Combining Experimental Example 1 and Experimental Example 2, it can be seen that the wear resistance and drag reduction performance of the triangular groove bionic surface layer are second only to the fence-shaped composite groove bionic surface layer in Example 1. Therefore, under the premise of simplifying the computational workload of the numerical simulation, it is referable to select the triangular groove bionic surface layer for the experiment.

[0045] In this experimental example, a two-dimensional fairing surface model of the hull is established using CAD software, and a triangular groove bionic surface layer is installed at the draft line height T and its nearby positions. The simulation results are shown in Figure 6 , when the triangular groove bionic surface layer is applied to different positions on the hull surface, the drag reduction rate is the highest when s / h = 1; installing the bionic surface layer near the draft line at the bow has a drag reduction effect. Among them, the bionic surface layer installed at T - 0.3T has the highest drag reduction rate; installing the bionic surface layer at the stern has a relatively obvious drag reduction at the propeller position and at a distance of T - 0.2T from the draft line.

[0046] Further numerical simulations of the three-dimensional hull surface flow field are carried out, and the drag reduction rates are shown in Table 3. Installing the triangular groove bionic surface layer (without a propeller) at T - 0.3T at the bow and T - 0.2T at the stern, where T represents the distance from the draft line to the bottom of the ship. The drag reduction rates of installing the triangular groove bionic surface layer at T - 0.3T at the bow and T - 0.2T at the stern are about 10%. In summary, installing the bionic surface layer has a certain drag reduction effect.

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

[0048] Fairing ship At the bow, T - 0.3T At the stern, T - 0.2T Drag force (N) 0.141 0.125 0.128 Drag reduction rate (%) 0 11.35 9.42

[0049] The above test examples illustrate that the composite bionic surface layer of the fence-shaped composite groove provided by the present invention can be applied to the hull and has effective drag reduction, wear resistance and anti-fouling functions. In addition, the size of the composite bionic surface layer provided by the present invention can be prepared according to parameters such as the actual length and draft of the hull and then pasted at different positions on the hull surface; when it is aged during use, a new composite bionic surface layer can be replaced through docking maintenance.

[0050] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A design method for a drag-reducing, anti-fouling and wear-resistant composite bionic surface layer structure, characterized in that: The following steps are involved: S1, simplify the surface texture of the mirror clam into triangular grooves; S2. Tilt the triangular groove 45° and then rotate it 90° to form a staggered fence-shaped composite groove.

2. The design method of the drag-reducing, anti-fouling and wear-resistant composite bionic surface layer structure according to claim 1 is characterized in that: The aspect ratio of the triangular groove is: s / h=1, wherein s represents the width of the triangular groove, and h represents the depth of the triangular groove; in the fence-shaped composite groove, the spacing b between adjacent triangular grooves is: b=2s.

3. The design method of the drag-reducing, anti-fouling and wear-resistant composite bionic surface layer structure according to claim 2 is characterized in that: The width of the triangular groove ranges from 0.1 mm to 0.2 mm.

4. A composite bionic surface layer structure with drag reduction, anti-fouling and wear resistance, characterized in that: The invention is designed by adopting the design method described in any one of claims 1 to 3.

5. The drag-reducing, anti-fouling and wear-resistant composite bionic surface layer structure according to claim 4 is characterized in that: It is a fence-shaped composite groove based on triangular grooves combined with the shield scale grooves on the shark skin surface.

6. A drag-reducing, anti-fouling and wear-resistant composite bionic surface layer, characterized in that: The composite bionic surface layer is made of resin composite material and arranged on the surface of the hull. The composite bionic surface layer has the structure described in any one of claims 4 to 5 or a structure designed by the design method described in any one of claims 1 to 3.

7. The drag-reducing, anti-fouling, and wear-resistant composite bionic surface layer according to claim 6, characterized in that: Stick it on the waterline of the ship which is prone to biofouling, the bottom of the ship which is prone to wear, and the hull surface near the propeller.

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