A drag-reducing and friction-reducing bionic texture for wading

Abstract

The present invention discloses a drag-reducing and friction-reducing bionic texture for wading, comprising a base material and a plurality of bionic protrusions provided on the surface of the base material. The bionic protrusions are generally fan-shaped columns, and a curved groove is provided downwardly at the top of the fan-shaped column. The curved groove has a concave steep slope on the side close to the axis of the fan-shaped column, and a concave gentle slope on the side close to the arc surface, forming a vortex groove as a whole. The intersection of the plane passing through the axis of the fan-shaped column and the curved groove is defined as a longitudinal section. All longitudinal sections of the fan-shaped column are the same. The top curve of the longitudinal section is a concave steep slope curve near the center of the fan-shaped column, and a gentle slope curve on the other side. Because the curved groove has a significant vortex effect, the drag-reducing and friction-reducing bionic texture can form a vortex in the seawater environment by flowing seawater, thereby forming a roller effect, converting sliding friction into rolling friction, and enhancing the fluid dynamic pressure effect, with a friction coefficient reduction rate of more than 60%.

Description

Technical Field

[0001] The present invention belongs to the field of bionic materials, and relates to a drag-reducing and friction-reducing bionic material, and in particular to a drag-reducing and friction-reducing bionic texture for wading. Background Art

[0002] Compared to the terrestrial environment, the marine environment is more demanding and complex. Components such as propellers for underwater vehicles are subject to a variety of loads during installation and service. They are also subject to corrosion caused by seawater and / or oil and gas media, as well as the effects of low or high temperature environments they may encounter. Therefore, improving the drag and friction reduction performance of components such as propellers for underwater vehicles is of great significance. To date, various surface engineering technologies such as high-intensity pulsed ion beam surface modification, laser cladding, ion implantation, physical vapor deposition, and laser surface texturing have been applied to improve the wear resistance of metal surfaces.

[0003] Among various surface engineering technologies, laser surface texturing has attracted widespread attention due to its advantages such as fast processing speed, high production efficiency, and good controllability. However, for underwater propellers, the current friction and drag reduction methods are complex and costly to prepare, making them difficult to scale up for industrial production. Achieving friction and drag reduction for underwater propellers requires a new type of surface texturing with a simple preparation process, economical operation, and ease of use. Summary of the Invention

[0004] The purpose of the present invention is precisely based on the above-mentioned problems, and a bionic texture for reducing drag and friction in wading is proposed, which can be applied to the surface drag reduction structure of underwater propellers. Due to the curved grooves on the top of the bionic protrusions, the vortex effect is obvious, and the flow of seawater in the seawater environment can be formed into vortices to form a "roller" effect, converting sliding friction into rolling friction and enhancing the fluid dynamic pressure effect. Compared with the blank sample, the friction coefficient reduction rate is as high as more than 60%.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A drag-reducing and friction-reducing bionic texture for wading comprises a base material and a plurality of bionic protrusions arranged on the surface of the base material. The bionic protrusions are generally fan-shaped columns, and a curved groove is downwardly provided at the top of the fan-shaped column. The curved groove has a steep concave slope on the side close to the axis of the fan-shaped column and a gentle concave slope on the side relatively close to the arc surface, forming an eddy current groove as a whole.

[0007] Furthermore, the intersection of the plane passing through the axis of the fan-shaped column and the curved groove is defined as a longitudinal section, and all longitudinal sections of the fan-shaped column are the same. The top curve of the longitudinal section is a concave steep slope curve close to the center of the fan-shaped column, and is a gentle slope curve in the other section.

[0008] Furthermore, the slopes of the concave steep slope curve and the gentle slope curve are both gradual, and the slope becomes steeper as the side approaches the center of the circle.

[0009] Furthermore, in the longitudinal section, the distance between the lowest point of the top curve and the axis of the sector column is 1 / 2-1 / 5 of the radius of the sector column.

[0010] Furthermore, the fan-shaped tip of the bionic protrusion is directed in the direction of the flow on the surface of the base material.

[0011] Furthermore, the bionic protrusion is a flat sector-shaped column as a whole, that is, the height-to-radius ratio of the sector-shaped column is less than 1.

[0012] Furthermore, the radius of the sector-shaped column is 0.1-100 microns, and the height of the sector-shaped column is 0.1-20 microns.

[0013] Furthermore, the distance between the lowest point of the top curve and the top of the sector column (the deepest depth of the curved groove) is 1 / 2-4 / 5 of the height of the sector column.

[0014] Furthermore, the bionic protrusions are distributed in an array shape on the surface of the base material, and further, can preferably be distributed in a row and column array shape.

[0015] Furthermore, the bionic protrusions account for 5%-40% of the surface area of ​​the base material.

[0016] Furthermore, the bionic protrusion is generated by first defining the longitudinal section shape, rotating the longitudinal section around the axis of the fan-shaped column. β Angle, that is, the bionic protrusion is obtained, β The value range is 30-150 degrees.

[0017] The drag and friction reduction principles of the present invention are as follows:

[0018] The present invention arranges micron-scale bionic protrusions on the surface of the base material. The bionic protrusions are fan-shaped columns as a whole. A curved groove is opened downward from the top of the fan-shaped column. The side of the curved groove close to the axis of the fan-shaped column is a steep concave slope, and the side relatively close to the arc surface is a gentle concave slope, forming an eddy groove as a whole. When the fluid passes through the bionic texture on the surface of the base material, the cross-sectional area of ​​the fluid becomes smaller. When passing through the edge of the fan-shaped column, the fluid is diverted from both sides of the edge tip into the curved groove at the top of the fan-shaped column. Since the curved groove is steep at first and then gentle, the diverted flow hits the side of the texture curved groove first to form a vortex, thereby forming a "roller" effect, converting sliding friction into rolling friction, and enhancing the fluid dynamic pressure effect, so as to achieve the purpose of reducing drag and friction.

[0019] From the above principles, it can be seen that the size level and density of the fan-shaped column, the depth of the curved groove on the top of the fan-shaped column, the depth of the curved groove on the bottom, the aspect ratio, the viscosity of the liquid, etc. all have a relatively large impact on the drag and friction reduction effect.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] (1) The preparation method is simple and easy. The experimental process only requires laser marking equipment and does not involve any organic reagents, which is in line with the green and environmentally friendly route.

[0022] (2) The processing materials are extensive and economical, and can be widely used in propellers made of various materials.

[0023] (3) The eddy current enhancement effect can form a roller-like motion, converting sliding friction into rolling friction.

[0024] (4) Excellent drag and friction reduction effects are achieved, with the friction coefficient reduction rate reaching above . BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the drag and friction reducing bionic texture in an embodiment of the present invention.

[0026] Figure 2 Schematic diagram of a single bionic protrusion structure in the drag and friction reducing bionic texture.

[0027] Figure 3 This is a top view of a single bionic protrusion structure in the drag and friction reducing bionic texture.

[0028] Figure 4 Schematic diagram of the longitudinal section of a single bionic protrusion structure in the drag and friction reducing bionic texture.

[0029] Figure 5 Comparison of friction coefficients of non-textured and textured samples in Example 1 of the present invention.

[0030] Figure 6 Comparison of friction coefficients of non-textured and textured samples in Example 2 of the present invention.

[0031] Figure 7 Comparison of friction coefficients of non-textured and textured samples in Example 3 of the present invention.

[0032] Figure 8 Schematic diagram of the flow field vector of the bionic texture for drag and friction reduction.

[0033] Figure 9 Schematic diagram of bionic texture fluid pressure for drag and friction reduction.

[0034] 100-propeller base material, 200-bionic protrusion, 210-fan-shaped column, 211-axis, 220-curved groove, 230-longitudinal section, 231-left vertical line, 232-right vertical line, 233-top curve, 234-bottom horizontal line, 240-lowest point. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0037] Example 1

[0038] like Figures 1 to 4 As shown, a drag and friction reducing bionic texture for underwater propellers includes a propeller base material 100 and an array of bionic protrusions 200 processed on the surface of the propeller base material 100. The density of the bionic protrusions 200 is 25% (accounting for the surface ratio of the propeller base material).

[0039] like Figure 2 As shown, the bionic protrusion 200 is a fan-shaped column 210 as a whole, and a curved groove 220 is provided downwardly at the top of the fan-shaped column. The curved groove 220 is a steep concave slope on the side close to the axis 211 of the fan-shaped column, and a gentle concave slope on the side relatively close to the arc surface, forming a vortex groove as a whole.

[0040] like Figure 2 As shown, the intersection of the plane passing through the axis line 211 of the sector column 210 and the curved groove 220 is defined as the longitudinal section 230. All longitudinal sections 230 of the sector column are the same, as shown in FIG. Figure 4 As shown, the top curve 233 of the longitudinal section 230 is close to the center of the fan-shaped column ( Figure 4 The middle right section) is a concave steep slope curve, relative to the other section ( Figure 4 The middle left section) is a gentle slope curve.

[0041] In this embodiment, the bionic protrusion 200 is generated as follows:

[0042] like Figure 3 and 4As shown, the longitudinal section of the bionic protrusion 200 is composed of a bottom horizontal line 234, a left vertical line 231, a right vertical line 232 and a top curve 233. The length of the bottom horizontal line 234 is the radius R = 10 microns of the fan-shaped column 210, the height of the vertical lines on the left and right sides is the height H = 3 microns of the fan-shaped column 210, and the top curve 233 is a concave smooth curve. The distance L = 0.25R = 2.5 microns between the lowest point 240 of the concave smooth curve and the right vertical line 232 is the depth H1 = 0.75H = 2.25 microns. The longitudinal section 230 is rotated around the right vertical line 232. β =90 degrees, that is, a single bionic protrusion is obtained; the bionic protrusions are selected to be distributed in an array on the surface of the substrate material, and the array method is a row and column array; the array density is 25%.

[0043] As a preferred embodiment, the direction of the fan-shaped tip of the bionic protrusion (the direction of the fan-shaped column edge) is the direction of the flow on the surface of the base material. Figure 3 As shown, the direction of the arrow is the flow direction of the fluid relative to the surface of the base material.

[0044] The above-mentioned structure is defined on the propeller surface using CAD, imported into the laser processing equipment, and laser processing is performed on the material surface twice.

[0045] It should be noted that Figure 1 The propeller base material is flat. In fact, the propeller base material is selected according to the actual shape. Figure 1 The diagram is only used to express the distribution morphology of the bionic protrusions on the matrix material, and does not mean that they can only be set on the surface of a planar structure. For a curved matrix material, it is sufficient that the axis of the fan-shaped column 210 coincides with or is parallel to the normal of the curved surface. Generally speaking, relative to the macroscopic structure of the matrix material, for the size of the fan-shaped column 210, the matrix material near the fan-shaped column 210 can be approximately regarded as a plane.

[0046] (1) Preparation of drag-reducing and friction-reducing bionic textures

[0047] A laser marking machine was used for processing, and the processing parameters were: linear speed 500 mm / s, processing power 2 J, laser frequency 30 Khz, and processing times 2 times.

[0048] (2) Friction reduction measurement method

[0049] The pin-on-disc rotation friction test was conducted on a pin-on-disc friction and wear testing machine: a UPE (ultra-high molecular weight polyethylene) pin with a diameter of 6.35 mm and a length of 19 mm was subjected to rotational friction against a 316L stainless steel disc with a diameter of 25 mm and a thickness of 10 mm.

[0050] Test conditions: load 10N, speed 300, 500, 700r / min (linear speed 0.785m / s, 1.309m / s, 1.833m / s)

[0051] (3) Comparative analysis of friction reduction results

[0052] Compared with the untextured 316L stainless steel sample, the friction coefficient did not decrease.

[0053] Its friction coefficient is compared with Figure 5 shown.

[0054] Example 2

[0055] A drag and friction reducing bionic texture for underwater propellers includes a propeller base material and arrayed bionic protrusions processed on the surface of the propeller base material. The density of the bionic protrusions is 30% (of the surface ratio of the propeller base material). The bionic protrusions are generated as follows:

[0056] See also Figure 4 As shown, the bionic protrusion is composed of a longitudinal section consisting of a bottom horizontal line, left and right vertical lines, and a top curve. The length of the bottom horizontal line is R = 10 microns, the height of the left and right vertical lines is H = 3 microns, the depth of the lowest point 240 of the concave smooth curve is H1 = 0.75H = 2.25 microns, the top curve is a concave smooth curve, and the distance between the lowest point of the concave smooth curve and the right vertical line is L = 0.25R = 2.5 microns. The longitudinal section is rotated around the right vertical line. β =60 degrees, that is, a single bionic protrusion is obtained; the bionic protrusions are selected to be distributed in an array on the surface of the substrate material, and the array method is a row and column array; the array density is 30%.

[0057] The above-mentioned structure is defined on the propeller surface using CAD, imported into the laser processing equipment, and laser processing is performed on the material surface twice.

[0058] (1) Preparation of drag-reducing and friction-reducing bionic textures

[0059] A laser marking machine was used for processing, and the processing parameters were: linear speed 500 mm / s, processing power 2 J, laser frequency 30 Khz, and processing times 2 times.

[0060] (2) Friction reduction measurement method

[0061] The pin-on-disc rotation friction test was carried out on a pin-on-disc friction and wear testing machine: a UPE (ultra-high molecular weight polyethylene) pin with a diameter of 6.35 mm and a length of 19 mm was subjected to rotational friction against a 316L stainless steel disc with a diameter of 25 mm and a thickness of 10 mm.

[0062] Test conditions: load 10N, speed 300, 500, 700r / min (linear speed 0.785m / s, 1.309m / s, 1.833m / s) (3) Comparative analysis of friction reduction results

[0063] Compared with the untextured 316L stainless steel sample, the friction coefficient is reduced by 60%.

[0064] Its friction coefficient is compared with Figure 6 shown.

[0065] Example 3

[0066] A drag and friction reducing bionic texture for underwater propellers includes a propeller base material and arrayed bionic protrusions processed on the surface of the propeller base material. The density of the bionic protrusions is 35% (of the surface ratio of the propeller base material). The bionic protrusions are generated as follows:

[0067] See also Figure 4 As shown, the bionic protrusion is composed of a longitudinal section consisting of a bottom horizontal line, left and right vertical lines, and a top curve. The length of the bottom horizontal line is R = 10 microns, the height of the left and right vertical lines is H = 3 microns, and the top curve is a concave smooth curve. The distance between the lowest point of the concave smooth curve and the right vertical line is L = 0.25r = 2.5 microns. The depth of the lowest point 240 of the concave smooth curve is H1 = 0.75H = 2.25 microns. The longitudinal section is rotated around the right vertical line. β =120 degrees, that is, a single bionic protrusion is obtained; the bionic protrusions are selected to be distributed in an array on the surface of the substrate material, and the array method is a row and column array; the array density is 35%.

[0068] The above-mentioned structure is defined on the propeller surface using CAD, imported into the laser processing equipment, and laser processing is performed on the material surface twice.

[0069] (1) Preparation of drag-reducing and friction-reducing bionic textures

[0070] A laser marking machine was used for processing, and the processing parameters were: linear speed 500 mm / s, processing power 2 J, laser frequency 30 Khz, and processing times 2 times.

[0071] (2) Friction reduction measurement method

[0072] The pin-on-disc rotation friction test was conducted on a pin-on-disc friction and wear testing machine: a UPE (ultra-high molecular weight polyethylene) pin with a diameter of 6.35 mm and a length of 19 mm was subjected to rotational friction against a 316L stainless steel disc with a diameter of 25 mm and a thickness of 10 mm.

[0073] Test conditions: load 10N, speed 300, 500, 700r / min (linear speed 0.785m / s, 1.309m / s, 1.833m / s)

[0074] (3) Comparative analysis of friction reduction results

[0075] Compared with the untextured 316L stainless steel sample, the friction coefficient is reduced by 14.8%.

[0076] Its friction coefficient is compared with Figure 7 shown.

[0077] In summary, the present invention proposes a drag-reducing and friction-reducing bionic texture for underwater propellers, wherein a drag-reducing and friction-reducing bionic texture similar to pangolin scales is laser-processed on the surface of the material, wherein the bionic protrusion area accounts for 5%-40%, and the shape of the pangolin scales is a uniformly distributed shield scale shape. The present invention uses fan-shaped columns with a concave curved surface on the top to imitate the shield scale shape to achieve a similar bionic effect. The preparation method of the drag-reducing and friction-reducing bionic texture is to set the density and individual size as required in CAD, and to split the individual texture by a layered and superimposed processing method, and to process multiple times to achieve a depth gradient structure at the bottom of the texture. Due to the gradient depth structure at the bottom of the texture, the vortex effect is obvious. The new bionic texture can form vortices in the seawater environment to form a "roller" effect, convert sliding friction into rolling friction, and enhance the fluid dynamic pressure effect. Compared with the blank sample, the friction coefficient reduction rate is as high as 60%. This bionic texture preparation method is simple and easy. The experimental process only requires laser processing equipment and does not involve any organic reagents. It conforms to the green and environmentally friendly route and can be widely used for underwater propeller surface texturing.

[0078] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A drag and friction reducing bionic texture for underwater propellers, characterized by: The bionic protrusions are formed on the surface of the substrate and are formed into a fan-shaped column. A curved groove is formed downward from the top of the fan-shaped column. The curved groove has a steep downward slope on the side close to the axis of the fan-shaped column and a gentle downward slope on the side close to the arc surface, forming a vortex groove as a whole. The intersection of the plane passing through the axis of the sector column and the curved groove is defined as the longitudinal section. All longitudinal sections of the sector column are the same. The top curve of the longitudinal section is a concave steep slope curve near the center of the sector column, and the other section is a gentle slope curve. The fan-shaped tip of the bionic protrusion is directed toward the flow direction of the surface of the base material; the radius of the fan-shaped column is 0.1-100 microns, and the height of the fan-shaped column is 0.1-20 microns.

2. The drag-reducing and friction-reducing bionic texture according to claim 1, characterized in that: The slopes of the concave steep slope curve and the gentle slope curve are both gradual, and the slope becomes steeper as the side approaches the center of the circle.

3. The drag-reducing and friction-reducing bionic texture according to claim 1, characterized in that: In the longitudinal section, the distance between the lowest point of the top curve and the axis of the sector column is 1 / 2-1 / 5 of the radius of the sector column.

4. The drag and friction reducing bionic texture according to claim 1, characterized in that: The bionic protrusion is a flat fan-shaped column as a whole.

5. The drag and friction reducing bionic texture according to claim 1, characterized in that: The bionic protrusions are distributed in an array shape on the surface of the base material.

6. The drag and friction reducing bionic texture according to claim 1, characterized in that: The bionic protrusions occupy 5%-40% of the surface area of ​​the base material.

7. The drag-reducing and friction-reducing bionic texture according to claim 1, characterized in that: The bionic protrusion is generated by first defining the longitudinal section shape, rotating the longitudinal section around the axis of the fan-shaped column, and then β Angle, that is, the bionic protrusion is obtained, β The value range is 30-150 degrees.

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