Bionic anti-fouling and drag-reducing surface structure, sonar tile and manufacturing method thereof

Abstract

The present invention discloses a bionic anti-fouling and drag-reducing surface structure, a sonar dome and a manufacturing method thereof. The bionic anti-fouling and drag-reducing surface structure includes a substrate and multiple groups of rib units located above the substrate. The rib units include a central main rib and side ribs located on both sides of the central main rib and spaced apart from it. The length of the central main rib is greater than the lengths of the side ribs on both sides of it. The substrate and the rib units are integrally cast and molded after mixing PDMS material with ZIFs solution. The bionic anti-fouling and drag-reducing surface structure proposed by the present invention can effectively reduce the navigation resistance of underwater equipment while having good hydrophobic and anti-fouling properties.

Description

Technical Field

[0001] The present invention relates to the technical field of ship drag reduction, and particularly to a bionic anti-fouling and drag reduction surface structure, anechoic tiles and a manufacturing method thereof. Background Art

[0002] At present, submarines and underwater vehicles face the problems of huge resistance consumption and serious biological fouling during service, which increase the navigation resistance and affect the overall performance. Relevant research points out that a serious biological fouling layer will increase the hull resistance by 50% to 60%. It is estimated that the economic losses caused by hull fouling are as high as $100 billion.

[0003] However, starting from the research on drag reduction mechanism alone often faces many difficulties in the complex marine environment. The drag reduction structure will reduce or even lose its original drag reduction function due to the attachment and fouling of marine organisms. Current research often focuses on the research of biological anti-fouling technology or drag reduction technology, making underwater equipment unable to meet the requirements of efficiency, energy consumption, maintenance cost and long-lasting service life at the same time. Summary of the Invention

[0004] The main purpose of the present invention is to provide a bionic anti-fouling and drag reduction surface structure, anechoic tiles and a manufacturing method thereof, aiming to reduce the navigation resistance of underwater equipment while having good hydrophobic and anti-fouling properties.

[0005] To achieve the above object, the present invention provides a bionic anti-fouling and drag reduction surface structure, including a substrate and multiple groups of rib units located above the substrate. The rib unit includes a central main rib and side ribs located on both sides of the central main rib and spaced from it. The length of the central main rib is greater than the length of the side ribs on both sides of it. The substrate and the rib unit are integrally cast and formed by mixing PDMS material and ZIFs solution.

[0006] Preferably, every four groups of rib units form a minimum anti-fouling and drag reduction structural block. A surrounding wall is provided on the outer periphery of the minimum anti-fouling and drag reduction structural block, and the bottom of the surrounding wall is fixedly connected to the top surface of the substrate.

[0007] Preferably, the surrounding wall is made of photosensitive resin.

[0008] Preferably, the central main rib and the side ribs have the same height, and the height of the surrounding wall is greater than the height of the central main rib.

[0009] Preferably, in the minimum anti-fouling and drag reduction structural block, the central connection lines of the central main ribs of the four groups of rib units form a rhombus.

[0010] Preferably, the surrounding wall encloses to form a rhombus structure.

[0011] Preferably, the side ribs on both sides of the central main rib are equal in length, and the centers of the side ribs on both sides of the central main rib in the length direction are located on the same straight line as the center of the central main rib in the length direction; the side ribs on both sides of the central main rib and the distance between them are equal.

[0012] Preferably, both the central main rib and the side ribs are in the shape of a cuboid.

[0013] The present invention further provides a sound-absorbing tile, on the surface of which the above-mentioned bionic anti-fouling and drag-reducing surface structure is provided.

[0014] The present invention also provides a manufacturing method based on the above-mentioned bionic anti-fouling and drag-reducing surface structure, including the following steps:

[0015] After mixing and stirring the A component of the PDMS material with the ZIFs solution, add the B component of the PDMS material and mix evenly;

[0016] Place the evenly mixed solution in a vacuum container for vacuum pumping to remove excess bubbles in the solution;

[0017] After spraying a silicone release agent on the surface of the silicon substrate negative template, pour the vacuumed solution onto the silicon substrate negative template;

[0018] After drying in an oven, peel the cured silicone sample from the mold to obtain a substrate and rib units.

[0019] The bionic anti-fouling and drag-reducing surface structure proposed by the present invention has the following beneficial effects:

[0020] (1) This bionic anti-fouling and drag-reducing surface structure has good drag-reducing performance, and the maximum drag reduction rate can reach 10%.

[0021] (2) Each rib unit is arranged in a staggered manner to form a continuous groove structure, which helps to improve the drag reduction effect;

[0022] (3) The non-smooth surface modified by ZIFs particles has both good anti-fouling performance and drag-reducing performance, and the surface contact angle is as high as 150°;

[0023] (4) This bionic anti-fouling and drag-reducing surface structure has the advantages of simple structure, easy implementation, good drag reduction and anti-fouling effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the bionic anti-fouling and drag-reducing surface structure of the present invention;

[0025] Figure 2 is Figure 1 The cross-sectional structural schematic diagram in the A-A direction shown;

[0026] Figure 3This is a schematic diagram of the detailed structure of the rib unit in the bionic anti-fouling and drag-reducing surface structure of the present invention after being modified by ZIFs.

[0027] In the figure, 1 - substrate, 2 - rib unit, 21 - central main rib, 22 - side rib, 3 - enclosure wall, 4 - ZIFs particles.

[0028] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Specific Embodiments

[0029] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the terms "horizontal", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] The present invention provides a bionic anti-fouling and drag-reducing surface structure.

[0032] Referring to Figures 1 to 3 , in this preferred embodiment, a bionic anti-fouling and drag-reducing surface structure includes a substrate 1 and multiple groups of rib units 2 located above the substrate 1. The rib unit 2 includes a central main rib 21 and side ribs 22 located on both sides of the central main rib 21 and spaced apart from it (it means that there is a gap between the side rib 22 and the central main rib 21 to form a groove). The lengths of the central main ribs 21 are all greater than the lengths of the side ribs 22 on both sides of them. The substrate 1 and the rib unit 2 are integrally cast and formed after mixing PDMS (polydimethylsiloxane) material with ZIFs (zeolitic imidazolate framework material) solution. Both the central main rib 21 and the side ribs 22 are in the shape of a cuboid.

[0033] Figure 1 The circle above the middle rib unit 2 and the straight line connecting the centers of the three rib units 2 are auxiliary lines and not specific structures. For the rib unit 2 adopting this structure, through the fluid simulation calculation of the SSTk-w model, using this surface microstructure can effectively reduce the fluid wall shear stress and control the reduction of the fluid vorticity component, thereby realizing the drag reduction function.

[0034] To endow the surface structure with excellent anti-fouling performance, in combination with the contact point theory, the bionic non-smooth surface was modified by compounding with zeolitic imidazolate framework materials (ZIFs) particles to enhance the anti-fouling and hydrophobic functions of the surface. After modification, the rib unit 2 is as shown in the appendix Figure 2 As shown, the ZIFs particles 4 are randomly arranged on the surface of the rib unit 2.

[0035] In this embodiment, with reference to Figure 1 and Figure 2 , taking the example that every four groups of rib units 2 form a minimum anti-fouling and drag-reducing structure block for specific illustration, the periphery of the minimum anti-fouling and drag-reducing structure block is provided with a surrounding wall 3, and the bottom of the surrounding wall 3 is fixedly connected to the top surface of the substrate 1. The surrounding wall 3 is made of photosensitive resin. The photosensitive resin is printed and formed on the substrate 1, thereby realizing the fixed connection between the substrate 1 and the surrounding wall 3. By protecting the minimum anti-fouling and drag-reducing structure block by the photosensitive resin surrounding wall 3, the anti-wear performance of the waterproof and anti-fouling surface is greatly improved, and the service life is extended.

[0036] Through the electron microscope observation of the shark skin sample, it is found that there are staggered placoid scale structures on the sample surface, and several rib structures exist on each placoid scale structure respectively. After staggered arrangement, the rib units will form a continuous groove structure. Relevant research shows that this groove structure is the key to the drag-reducing mechanism of shark skin. By extracting the groove characteristic parameters on the surface of the placoid scale crown, the arrangement mode of the simplified minimum drag-reducing structure block and its internal rib unit 2 is as shown in the appendix Figure 1 As shown.

[0037] Specifically, with reference to Figure 2 , the height of the central main rib 21 is equal to that of the side ribs 22, and the height of the surrounding wall 3 is greater than that of the central main rib 21. In the minimum anti-fouling and drag-reducing structure block, the center connection lines of the central main ribs 21 of the four groups of rib units 2 form a rhombus. The surrounding wall 3 encloses to form a rhombus structure.

[0038] In this embodiment, with reference to Figure 1 and Figure 3 , the lengths of the side ribs 22 on both sides of the central main rib 21 are equal, and the centers of the side ribs 22 on both sides of the central main rib 21 in the length direction are located on the same straight line as the center of the central main rib 21 in the length direction. The distances between the side ribs 22 on both sides of the central main rib 21 are equal.

[0039] Furthermore, multiple groups of rib units 2 are staggered (which means that Figure 1 the rib units 2 in the upper and lower rows are staggered and not in the same column). To prevent the reduction of the hydrophobic performance caused by the wear of the ZIFs particles 4, the surface structures are arranged in a staggered manner in the surrounding wall 3.

[0040] In this embodiment, with reference to Figure 1, the rib units are staggered with the vertices of a rhombus with a side length of 2000 μm as the center, and are surrounded by a surrounding wall 3 of an equilateral rhombus with a side length of 4000 μm and a height of 120 μm on the outside. The rib unit 2 is composed of a central main rib 21 and a pair of side ribs 22. The width of a single rib is 40 μm and the height is 60 μm. The length of the central main rib 21 is about 1000 μm, and the length of the side rib 22 is about 400 μm. Through the fluid simulation calculation of the SST k-ω model, using this surface microstructure can effectively reduce the fluid wall shear stress and control the reduction of the fluid vorticity component, thereby realizing the drag reduction function.

[0041] The manufacturing process of this bionic anti-fouling and drag-reducing surface structure is as follows. Use lithography technology to process a high-precision silicon substrate negative mold, and select a PDMS material with a lower surface energy for the molding of the non-smooth surface by casting. When configuring the PDMS silicone casting material, first, take the component A material of the PDMS material and mix and stir it with the ZIFs solution. After the ZIFs are fully dispersed, mix the mixed solution with the component B material of the PDMS material, and then place it in a vacuum container to evacuate to remove the excess bubbles in the solution. After spraying a layer of silicone mold release agent on the surface of the silicon substrate negative template, pour the solution onto the silicon substrate negative template. After drying in an oven, peel the cured silicone sample from the mold. Finally, print photosensitive resin on the substrate 1 to form the surrounding wall 3.

[0042] The rib units 2 are staggered on the completed non-smooth surface, and its drag reduction mechanism is as follows:

[0043] First, the near-wall velocity of the non-smooth surface is small and shows a low-gradient growth trend; second, the non-smooth surface can effectively inhibit the high turbulent kinetic energy region nearby, reducing the total turbulent kinetic energy; third, the non-smooth surface can reduce the streamwise vorticity component nearby, reducing the transverse velocity of the fluid flow and the momentum loss of the flow. In summary, the staggered rib units 2 have a certain drag reduction effect, and the maximum drag reduction rate can reach 10%.

[0044] ZIFs particles 4 are uniformly dispersed on the completed non-smooth surface, forming a rough surface on the basis of the original non-smooth surface, similar to the papilla structure of the lotus leaf surface, thus constructing a secondary-scale non-smooth surface. After testing, it can effectively improve the anti-biofouling ability, and the surface contact angle is as high as 150°, approaching superhydrophobic materials.

[0045] The bionic anti-fouling and drag-reducing surface structure proposed by the present invention has the following beneficial effects:

[0046] (1) This bionic anti-fouling and drag-reducing surface structure has good drag reduction performance, and the maximum drag reduction rate can reach 10%.

[0047] (2) Each rib unit is staggered to form a continuous groove structure, which helps to improve the drag reduction effect;

[0048] (3) The non-smooth surface modified by ZIFs particles 4 has both good anti-fouling performance and drag reduction performance, and the surface contact angle is as high as 150°.

[0049] (4) This bionic anti-fouling and drag reduction surface structure has the advantages of simple structure, easy implementation, good drag reduction and anti-fouling effects.

[0050] The present invention further provides a sonar tile.

[0051] In this preferred embodiment, a sonar tile has a bionic anti-fouling and drag reduction surface structure on its surface. For the specific structure and beneficial effects of the bionic anti-fouling and drag reduction surface structure, please refer to the above embodiments and will not be elaborated here.

[0052] The present invention further provides a manufacturing method of the bionic anti-fouling and drag reduction surface structure.

[0053] In this preferred embodiment, a manufacturing method of the bionic anti-fouling and drag reduction surface structure based on the above includes the following steps:

[0054] Step S10: After mixing and stirring the PDMS material component A with the ZIFs solution, add the PDMS material component B and mix evenly.

[0055] Step S20: Place the evenly mixed solution in a vacuum container and evacuate it to remove excess bubbles in the solution.

[0056] Step S30: After spraying a silicone mold release agent on the surface of the silicon substrate negative template, pour the evacuated solution onto the silicon substrate negative template.

[0057] Step S40: After drying the silicon substrate negative template after pouring in an oven, peel the cured silicone sample from the mold to obtain the substrate 1 and the rib unit 2.

[0058] The manufacturing method of the bionic anti-fouling and drag reduction surface structure proposed by the present invention has low manufacturing cost, simple manufacturing process and long service life, and is suitable for large-scale mass production.

[0059] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A bionic anti-fouling and drag-reducing surface structure, characterized in that, It includes a substrate and multiple groups of rib units located above the substrate. The rib units include a central main rib and side ribs located on both sides of the central main rib and spaced apart from it. The length of the central main rib is greater than the lengths of the side ribs on both of its sides. The substrate and the rib units are integrally formed by casting after mixing PDMS material with ZIFs solution; every four groups of rib units form a minimum anti-fouling and drag-reducing structural block. A surrounding wall is provided on the outer periphery of the minimum anti-fouling and drag-reducing structural block. The bottom of the surrounding wall is fixedly connected to the top surface of the substrate; the surrounding wall is made of photosensitive resin; the central main rib and the side ribs have the same height, and the height of the surrounding wall is greater than the height of the central main rib; both the central main rib and the side ribs are in the shape of a cuboid.

2. The bionic anti-fouling and drag-reducing surface structure according to claim 1, characterized in that, In the minimum anti-fouling and drag-reducing structural block, the center connection lines of the central main ribs of the four groups of rib units form a rhombus.

3. The bionic anti-fouling and drag-reducing surface structure according to claim 1, characterized in that, The surrounding wall encloses to form a rhombus structure.

4. The bionic anti-fouling and drag-reducing surface structure according to claim 1, characterized in that, The side ribs on both sides of the central main rib have equal lengths, and the centers in the length direction of the side ribs on both sides of the central main rib and the center in the length direction of the central main rib are on the same straight line; the side ribs on both sides of the central main rib are equidistant from each other.

5. A sonar tile, characterized in that, Its surface is provided with the bionic anti-fouling and drag-reducing surface structure as described in any one of claims 1 to 4.

6. A manufacturing method of a bionic anti-fouling and drag-reducing surface structure according to any one of claims 1 to 4, characterized in that, It includes the following steps: After mixing and stirring the A component material of PDMS material with ZIFs solution, add the B component material of PDMS material and mix evenly. Place the evenly mixed solution in a vacuum container for vacuum pumping to remove excess bubbles in the solution. After spraying silicone release agent on the surface of the silicon substrate negative template, pour the vacuumed solution onto the silicon substrate negative template. After drying in an oven, peel the cured silicone sample from the mold to obtain the substrate and the rib units.

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