Coronary turbulent flow drag reduction micro-rib structure

Abstract

The application discloses a crown-shaped turbulent flow drag-reducing micro-rib structure and belongs to the technical field of aeronautics.The application aims to improve the drag-reducing effect of the micro-rib structure.The application comprises a surface base body and a plurality of drag-reducing small ribs.The drag-reducing small ribs are long strip structures with equal cross sections, extend along the fluid flow direction, are arranged in sequence and at intervals along the direction perpendicular to the fluid flow direction, and comprise a crown body and a rib main body connected in sequence.The cross sections of the crown body and the rib main body are all isosceles trapezoids, the lower bottom surface of the crown body is equal to and aligned with the upper top surface of the rib main body, an isosceles trapezoidal groove is arranged on the upper top surface of the crown body and extends through the length direction of the crown body, the top of the crown body forms two left-right symmetrical convex structures, and the lower bottom surface of the rib main body is connected with the surface base body.The pipe body can generate stronger secondary vortex structures under the same flow field conditions, has a stronger inhibiting effect on the spanwise oscillation of the main flow direction vortex, and thus improves the drag-reducing effect.

Description

Technical Field

[0001] This invention belongs to the field of aerospace engineering technology, and in particular relates to a crown-shaped turbulence drag reduction microrib structure. Background Technology

[0002] Frictional drag accounts for over 50% of the drag in civil aircraft, and this type of drag is independent of the specific aircraft layout, depending solely on the boundary layer state of the fuselage surface. Particularly for aircraft fuselages with long flow directions, due to the high local Reynolds number, most areas are controlled by turbulent boundary layers that generate significant frictional drag due to flow transitions. To meet the requirements of green aviation development, reducing the drag of civil aircraft, especially the frictional drag on the fuselage surface, has become a hot research topic in aircraft drag reduction technology.

[0003] With the development of aerospace materials and high-precision manufacturing technology for complex surfaces, microrib turbulence drag reduction technology, derived from the biomimetic structure of shark skin, has attracted increasing attention due to its advantages of low cost, high returns, simple maintenance, and wide applicability. Its basic principle involves attaching downstream microribs to the fuselage surface, with a height not exceeding the thickness of the bottom of the turbulent boundary layer. The typical cross-section of these ribs is triangular or trapezoidal, with a certain spacing between adjacent ribs. The protruding rib structure, through the lateral flow of airflow, forms a secondary vortex structure, thereby suppressing the spanwise oscillation of quasi-stream vortices within the turbulent boundary layer, reducing flow structure abruptness, suppressing turbulent dissipation, and ultimately reducing turbulent drag.

[0004] Besides drag reduction performance, durability is also a crucial indicator of the overall performance of microrib surface structures. When material quality is comparable, durability is closely related to the microrib structure and its stress characteristics. For the small ribs on the microrib surface, to form a sufficiently strong secondary vortex structure, their tips protrude beyond the boundary layer and are subjected to high-speed airflow, creating a localized high-friction zone. To minimize the size of this high-friction zone, the width of the rib tip is typically minimized. When the rib tip width is close to zero, it corresponds to a triangular cross-section; when the rib tip has a certain width, it corresponds to a trapezoidal cross-section. Because the rib tip width is relatively larger, the durability of trapezoidal cross-section microrib structures is better than that of triangular cross-section microrib structures.

[0005] To understand the influence mechanism of the microrib surface rib structure on drag reduction and durability, it is necessary to explore a more efficient rib structure in order to maximize the drag reduction and durability performance of the rib structure. That is, while obtaining a sufficiently strong secondary vortex, the size of the high friction region at the tip of the rib should be minimized to achieve a perfect balance between drag reduction and durability performance of the rib structure. Summary of the Invention

[0006] This invention aims to find a novel drag-reducing microrib structure, distinct from existing triangular or trapezoidal cross-sections, capable of generating secondary vortex structures of comparable strength while significantly reducing friction at the rib tips. This reduces the high-friction zone of the ribs themselves, lowering their inherent drag and improving drag reduction performance. Furthermore, it weakens airflow wear on the rib tips, enhancing durability. Based on these considerations, this invention proposes a turbulent drag-reducing microrib structure with a crown-shaped cross-section from a vortex control perspective. The crown-shaped structure at the rib tips enhances the ribs' ability to generate secondary vortices. While maintaining the same intensity of secondary vortex generation, the rib height is appropriately reduced, thereby decreasing the additional drag of the ribs themselves, reducing wear, and achieving a dual improvement in drag reduction and durability. The technical solution adopted in this invention is as follows:

[0007] A crown-shaped turbulence drag-reducing microrib structure includes a surface substrate and several drag-reducing ribs. The drag-reducing ribs are elongated structures with uniform cross-sections, extending along the fluid flow direction. Several drag-reducing ribs are arranged sequentially at intervals perpendicular to the fluid flow direction. Each drag-reducing rib includes a crown and a rib body connected vertically. The cross-sections of both the crown and the rib body are isosceles trapezoidal. The upper base of the crown cross-section is longer than the lower base, and the lower base of the rib body cross-section is longer than the upper base. The lower base of the crown and the upper top surface of the rib body are aligned equally. An isosceles trapezoidal groove is provided on the upper top surface of the crown. The upper base of the isosceles trapezoidal groove is longer than the lower base. The isosceles trapezoidal groove is arranged through the crown along its length, forming two symmetrical protrusions at the top of the crown. The lower base of the rib body is connected to the surface substrate.

[0008] Furthermore, the drag-reducing ribs extend in a straight line or in a wavy shape along the fluid flow direction.

[0009] Furthermore, the spacing between adjacent drag-reducing ribs is set as s (μm), the height of the drag-reducing ribs is set as h (μm), the height of the rib body is set as h1 (μm), the depth of the isosceles trapezoidal groove is set as h2 (μm), the bottom width of the rib body is set as s1 (μm), the included angle between the two inclined surfaces of the rib body is set as a1 (°), the top width of the crown is set as s2 (μm), the included angle between the two inclined surfaces of the crown is set as a2 (°), the groove opening width of the isosceles trapezoidal groove is set as s3 (μm), and the included angle between the two inclined surfaces of the isosceles trapezoidal groove is set as a3 (°).

[0010] For the turbulent boundary layer flow field where the drag-reducing rib is located, the fluid density is set as ρ, with units of kg / m³. 3 The kinematic viscosity is ν, and the unit is mm. 2 / s, the local frictional shear stress is τ, in Pa, and the frictional velocity is ut, in m / s. The frictional velocity ut is then calculated using the following formula:

[0011] ut=(τ / ρ)0.5 ;

[0012] Let the viscosity scale be δv, with units of μm. Then, the viscosity scale δv is calculated by the following formula:

[0013] δv=ν / ut;

[0014] Let the dimensionless spacing between adjacent drag-reducing ribs be s+, which is calculated using the following formula:

[0015] s += s / δv;

[0016] The ratio of the width s to the height h of the drag-reducing rib is set as the width-to-height ratio rh, which is calculated by the following formula:

[0017] rh = h / s.

[0018] Furthermore, let's define the ratio of the height h1 of the rib body to the overall height h of the drag-reducing rib as the relative height rh1, the ratio of the depth h2 of the isosceles trapezoidal groove to the crown height (h-h1) as the relative depth rh2, the ratio of the bottom width s1 of the rib body to the distance s between two adjacent drag-reducing ribs as the relative width rs1, the ratio of the top width s2 of the crown to the bottom width s1 of the rib body as the relative width rs2, and the ratio of the groove width s3 of the isosceles trapezoidal groove to the top width s2 of the crown as the relative groove width rs3. Then, rh1 is calculated using the following formula:

[0019] rh1=h1 / h;

[0020] rh2 is calculated using the following formula:

[0021] rh2 = h2 / (h - h1);

[0022] rs1 is calculated using the following formula:

[0023] rs1 = s1 / s;

[0024] rs2 is calculated using the following formula:

[0025] rs2 = s2 / s1;

[0026] rs3 is calculated using the following formula:

[0027] rs3 = s3 / s2.

[0028] Furthermore, the values ​​of s+ range from 10 to 30, rh ranges from 0.2 to 1, rh1 ranges from 0.5 to 0.8, rh2 ranges from 0.2 to 0.8, rs1 ranges from 0.3 to 0.5, rs2 ranges from 0.6 to 1, rs3 ranges from 0.4 to 0.8, a1 ranges from 20° to 60°, a2 ranges from 20° to 60°, and a3 ranges from 50° to 120°.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The crown-shaped turbulent drag reduction microrib structure proposed in this invention draws on the structural characteristics of vortex generators. The crown at the top of the drag reduction rib can generate stronger secondary vortices under the same flow field conditions, which has a stronger suppression effect on the spanwise oscillation of the mainstream flow vortex, thereby achieving the purpose of improving drag reduction effect.

[0031] 2. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a larger spanwise space ratio, which can effectively isolate the influence of the mainstream flow on the flow at the bottom of the drag reduction microrib, further reducing the flow velocity at the bottom, thereby reducing the frictional resistance in the bottom region of the drag reduction microrib and achieving the purpose of improving the drag reduction effect.

[0032] 3. The crown-shaped turbulence drag reduction microrib structure proposed in this invention forms an isosceles trapezoidal groove between two symmetrical protrusions, which can reduce the exposed area ratio of the high friction zone and reduce the friction resistance of the crown at the top of the drag reduction rib, thereby achieving the purpose of improving the drag reduction effect.

[0033] 4. The crown-shaped turbulent drag-reducing microrib structure proposed in this invention has an isosceles trapezoidal groove that can enhance the three-dimensional flow effect at the tip of the drag-reducing rib and weaken the scouring effect of high-speed airflow on the drag-reducing rib itself. While reducing the frictional resistance at the tip of the drag-reducing rib, it also reduces structural wear, thereby achieving a simultaneous improvement in drag reduction performance and durability.

[0034] 5. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a crown with an isosceles trapezoidal groove at the top. Compared with the top of the conventional trapezoidal cross-section rib, it has a smaller structural stiffness. While maintaining the ability to generate secondary vortices, it can weaken the scouring effect of high-speed airflow on the drag reduction rib itself through local deformation, thereby achieving a simultaneous improvement in drag reduction performance and durability.

[0035] 6. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a crown size that is significantly larger than the top size of conventional small rib structures. This allows for the use of wear-resistant materials in the crown portion through a step-by-step fabrication process, thereby achieving simultaneous improvement in drag reduction performance and durability. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the present invention when the microribs extend in a straight line;

[0037] Figure 2 This is a schematic diagram of the structure of the present invention when the micro-ribs are extended in a waveform;

[0038] Figure 3 This is a schematic diagram of the cross-sectional structure of two adjacent microribs;

[0039] Figure 4 This is a schematic diagram of the cross-sectional dimensions of two adjacent microribs;

[0040] Figure 5 This is a comparative schematic diagram showing the secondary vortex characteristics formed by the drag-reducing ribs and trapezoidal cross-section microribs of the present invention under the same crossflow action;

[0041] Figure 6 This is a schematic diagram comparing the flow vortex and secondary vortex structural characteristics of the present invention and the trapezoidal cross-section microrib structure under the same crossflow action;

[0042] Figure 7 This is a comparison diagram of the flow velocity profile of the present invention and the trapezoidal cross-section microrib structure;

[0043] Figure 8 This is a comparison diagram of the spanwise velocity profile of the present invention and the trapezoidal cross-section microrib structure.

[0044] In the figure, 1. Surface substrate, 2. Drag-reducing rib, 3. Rib body, 4. Crown, 5. Isosceles trapezoidal groove, 6. Protruding structure. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0046] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as bolted connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can be found to achieve this function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a bolted connection can be chosen for detachable connections.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0048] Example: Figures 1 to 8 As shown, a crown-shaped turbulence drag reduction microrib structure includes a surface substrate 1 and several drag reduction ribs 2. The drag reduction ribs 2 are elongated structures with equal cross-sections and extend along the fluid flow direction. Several drag reduction ribs 2 are arranged sequentially at intervals perpendicular to the fluid flow direction. Each drag reduction rib 2 includes a crown 4 and a rib body 3 connected vertically. The cross-sections of the crown 4 and the rib body 3 are both isosceles trapezoids. The upper base of the cross-section of the crown 4 is longer than the lower base, and the lower base of the cross-section of the rib body 3 is longer than the upper base. The lower base surface of the crown 4 and the upper top surface of the rib body 3 are aligned equally. An isosceles trapezoidal groove 5 is provided on the upper top surface of the crown 4. The upper base of the cross-section of the isosceles trapezoidal groove 5 is longer than the lower base. The isosceles trapezoidal groove 5 is arranged through the length direction of the crown 4, so that the top of the crown 4 forms two symmetrical protrusions 6. The lower base surface of the rib body 3 is connected to the surface substrate 1.

[0049] The drag-reducing rib 2 extends in a straight line or in a wave shape along the fluid flow direction.

[0050] Let the spacing between adjacent drag-reducing ribs 2 be s (in μm), the height of drag-reducing ribs 2 be h (in μm), the height of the rib body 3 be h1 (in μm), the depth of the isosceles trapezoidal groove 5 be h2 (in μm), the bottom width of the rib body 3 be s1 (in μm), the included angle between the two inclined surfaces of the rib body 3 be a1 (in °), the top width of the crown 4 be s2 (in μm), the included angle between the two inclined surfaces of the crown 4 be a2 (in °), the groove width of the isosceles trapezoidal groove 5 be s3 (in μm), and the included angle between the two inclined surfaces of the isosceles trapezoidal groove 5 be a3 (in °).

[0051] For the turbulent boundary layer flow field where the drag-reducing rib 2 is located, the fluid density is set as ρ, with units of kg / m³. 3 The kinematic viscosity is ν, and the unit is mm. 2 / s, the local frictional shear stress is τ, in Pa, and the frictional velocity is ut, in m / s. The frictional velocity ut is then calculated using the following formula:

[0052] ut=(τ / ρ) 0.5 ;

[0053] Let the viscosity scale be δv, with units of μm. Then, the viscosity scale δv is calculated by the following formula:

[0054] δv=ν / ut;

[0055] Let the dimensionless spacing between adjacent drag-reducing ribs 2 be s+, which is calculated by the following formula:

[0056] s += s / δv;

[0057] The ratio of the width s to the height h of the drag-reducing rib 2 is set as the width-to-height ratio rh, which is calculated by the following formula:

[0058] rh = h / s.

[0059] Define the ratio of the height h1 of the rib body 3 to the overall height h of the drag-reducing rib 2 as the relative height rh1; the ratio of the depth h2 of the isosceles trapezoidal groove 5 to the height (h-h1) of the crown 4 as the relative depth rh2; the ratio of the bottom width s1 of the rib body 3 to the distance s between two adjacent drag-reducing ribs 2 as the relative width rs1; the ratio of the top width s2 of the crown 4 to the bottom width s1 of the rib body 3 as the relative width rs2; and the ratio of the groove width s3 of the isosceles trapezoidal groove 5 to the top width s2 of the crown 4 as the relative groove width rs3. Then rh1 is calculated by the following formula:

[0060] rh1=h1 / h;

[0061] rh2 is calculated using the following formula:

[0062] rh2 = h2 / (h - h1);

[0063] rs1 is calculated using the following formula:

[0064] rs1 = s1 / s;

[0065] rs2 is calculated using the following formula:

[0066] rs2 = s2 / s1;

[0067] rs3 is calculated using the following formula:

[0068] rs3 = s3 / s2.

[0069] rh1, rh2, rs1, rs2, and rs3 are all dimensionless parameters.

[0070] To achieve drag reduction during turbulence, the drag-reducing rib 2 structure requires the following values ​​under the corresponding fluid flow conditions: s+ ranges from 10 to 30, rh ranges from 0.2 to 1, rh1 ranges from 0.5 to 0.8, rh2 ranges from 0.2 to 0.8, rs1 ranges from 0.3 to 0.5, rs2 ranges from 0.6 to 1, rs3 ranges from 0.4 to 0.8, a1 ranges from 20° to 60°, a2 ranges from 20° to 60°, and a3 ranges from 50° to 120°.

[0071] Figure 5This diagram illustrates a comparison between the local flow field at the tip of the trapezoidal cross-section microrib and the present invention. The upper part shows the secondary vortex characteristic diagram of the local flow field at the tip of the drag-reducing microrib 2 of the present invention, while the lower part shows the secondary vortex characteristic diagram of the local flow field at the tip of the trapezoidal cross-section microrib. Figure 6 This demonstrates a comparison of the flow field of the present invention with that of the trapezoidal cross-section microrib. The upper part shows the flow field directional vortex and secondary vortex characteristic diagram of the overall flow field of the drag-reducing microrib 2 of the present invention, and the lower part shows the flow field directional vortex and secondary vortex characteristic diagram of the overall flow field of the trapezoidal cross-section microrib.

[0072] Figure 7 This is a comparison diagram of the flow velocity profile of the present invention and the trapezoidal cross-section microrib structure. Figure 8 This is a comparison diagram of the spanwise velocity profile of the present invention and the trapezoidal cross-section microrib structure.

[0073] Under the same crossflow conditions, compared to the trapezoidal cross-section ribs, the drag-reducing ribs 2 of this invention can generate stronger secondary vortices under the same flow field conditions, and have a stronger suppressive effect on the spanwise oscillation of the mainstream flow vortex. At the same time, the larger spanwise space ratio can also effectively isolate the influence of the mainstream flow on the bottom flow of the microrib structure, further reducing the bottom flow velocity.

[0074] Numerical simulations were performed based on the RANS equations, using a trapezoidal cross-section microrib as a control. This trapezoidal cross-section microrib has the same width, base length, aspect ratio (0.5), and 30° angle between its two sides, and extends along a straight line as the drag-reducing rib 2. The calculated drag reduction rate of the trapezoidal cross-section turbulent drag-reducing microrib structure was 7.98%, while the drag reduction rate of the proposed microrib structure was 10.89%. This demonstrates that the proposed crown-shaped turbulent drag-reducing microrib structure increases the drag reduction rate by 36.46% compared to the trapezoidal structure. The flow-direction and spanwise velocity profiles show that the crown-shaped turbulent drag-reducing microrib structure significantly shifts the velocity profile upwards, thus reducing drag.

[0075] From the perspective of vortex control, this invention proposes a turbulence drag reduction microrib structure with a crown-shaped cross-section. The drag-reducing rib 2 of the microrib structure consists of two parts: a rib body 3 and a crown 4. The rib body 3 is an isosceles trapezoid, and the crown 4 is an inverted isosceles trapezoid with a through trapezoidal groove on its top surface. Overall, the cross-section of the drag-reducing rib 2 is symmetrical on both sides, with concave broken lines on both sides. The top of the cross-section of the drag-reducing rib 2 has a left and right separated protrusion structure 6.

[0076] Compared with the prior art, the present invention has the following advantages:

[0077] 1. The crown-shaped turbulent drag reduction microrib structure proposed in this invention draws on the structural characteristics of vortex generators. The crown 4 at the top of the drag reduction rib 2 can generate stronger secondary vortices under the same flow field conditions, which has a stronger suppression effect on the spanwise oscillation of the mainstream flow vortex, thereby achieving the purpose of improving drag reduction effect.

[0078] 2. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a larger spanwise space ratio of crown 4, which can effectively isolate the influence of mainstream flow on the bottom flow of drag reduction rib 2, further reduce the bottom flow velocity, thereby reducing the frictional resistance in the bottom region of drag reduction rib 2 and achieving the purpose of improving drag reduction effect.

[0079] 3. The crown-shaped turbulent drag reduction microrib structure proposed in this invention forms an isosceles trapezoidal groove 5 between two symmetrical protrusions 6, which can reduce the exposed area ratio of the high friction zone and reduce the friction resistance of the crown 4 at the top of the drag reduction rib 2, thereby achieving the purpose of improving the drag reduction effect.

[0080] 4. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has an isosceles trapezoidal groove 5 that can enhance the three-dimensional flow effect at the top of the drag reduction rib 2, weaken the scouring effect of high-speed airflow on the drag reduction rib 2 itself, reduce the frictional resistance at the top of the drag reduction rib 2, and reduce structural wear, thereby achieving a simultaneous improvement in drag reduction performance and durability.

[0081] 5. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a crown 4 with an isosceles trapezoidal groove 5 at the top. Compared with the top of the conventional trapezoidal cross section of the small rib, it has a smaller structural stiffness. While maintaining the ability to generate secondary vortices, it can weaken the scouring effect of high-speed airflow on the drag reduction small rib 2 itself through local deformation, thereby achieving simultaneous improvement in drag reduction performance and durability performance.

[0082] 6. The crown-shaped turbulent drag reduction microrib structure proposed in this invention has a crown 4 with a size that is significantly larger than the top size of a conventional small rib structure. This allows for the use of wear-resistant materials in the crown 4 part through a step-by-step preparation method, thereby achieving simultaneous improvement in drag reduction performance and durability.

[0083] The above embodiments are merely illustrative examples of the present invention and do not limit its scope of protection. Those skilled in the art can make partial changes to them, as long as they do not exceed the spirit and essence of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A crown-shaped turbulence drag reduction microrib structure, characterized in that: It includes a surface substrate (1) and several drag-reducing ribs (2). The drag-reducing ribs (2) are elongated structures with equal cross-sections. The drag-reducing ribs (2) extend along the fluid flow direction. Several drag-reducing ribs (2) are arranged alternately along the direction perpendicular to the fluid flow. The drag-reducing ribs (2) include a crown (4) and a rib body (3) connected vertically. The cross-sections of the crown (4) and the rib body (3) are both isosceles trapezoids. The upper base of the cross-section of the crown (4) is longer than the lower base. The rib body (3) The lower base of the cross section of the crown (4) is longer than the upper base, and the lower base of the crown (4) and the upper top surface of the rib body (3) are aligned. An isosceles trapezoidal groove (5) is provided on the upper top surface of the crown (4). The upper base of the cross section of the isosceles trapezoidal groove (5) is longer than the lower base. The isosceles trapezoidal groove (5) is provided through the length direction of the crown (4), so that the top of the crown (4) forms two left-right symmetrical protrusions (6). The lower base of the rib body (3) is connected to the surface substrate (1).

2. The crown-shaped turbulence drag reduction microrib structure according to claim 1, characterized in that: (2) The drag-reducing rib extends in a straight line or in a wave shape along the fluid flow direction.

3. The crown-shaped turbulence drag reduction microrib structure according to claim 1, characterized in that: The spacing between adjacent drag-reducing ribs (2) is set as s, in μm; the height of drag-reducing ribs (2) is h, in μm; the height of the rib body (3) is h1, in μm; the depth of the isosceles trapezoidal groove (5) is h2, in μm; the bottom width of the rib body (3) is s1, in μm; the angle between the two inclined surfaces of the rib body (3) is a1, in °; the top width of the crown (4) is s2, in μm; the angle between the two inclined surfaces of the crown (4) is a2, in °; the groove width of the isosceles trapezoidal groove (5) is s3, in μm; and the angle between the two inclined surfaces of the isosceles trapezoidal groove (5) is a3, in °. For the turbulent boundary layer flow field where the drag-reducing rib (2) is located, the fluid density is set to ρ, with units of kg / m³. 3 The kinematic viscosity is ν, and the unit is mm. 2 / s, the local frictional shear stress is τ, in Pa, and the frictional velocity is ut, in m / s. The frictional velocity ut is then calculated using the following formula: as=(τ / ρ) 0.5 ; Let the viscosity scale be δv, with units of μm. Then, the viscosity scale δv is calculated by the following formula: δv=ν / ut; Let the dimensionless spacing between adjacent drag-reducing ribs (2) be s+, and s+ be calculated by the following formula: s += s / δv; The width s and height h of the drag-reducing rib (2) are set as the width-to-height ratio rh, which is calculated by the following formula: rh = h / s.

4. The crown-shaped turbulence drag reduction microrib structure according to claim 3, characterized in that: Define the ratio of the height h1 of the rib body (3) to the overall height h of the drag-reducing rib (2) as the relative height rh1, the ratio of the depth h2 of the isosceles trapezoidal groove (5) to the height (h-h1) of the crown (4) as the relative depth rh2, the ratio of the bottom width s1 of the rib body (3) to the distance s between two adjacent drag-reducing ribs (2) as the relative width rs1, the ratio of the top width s2 of the crown (4) to the bottom width s1 of the rib body (3) as the relative width rs2, and the ratio of the groove width s3 of the isosceles trapezoidal groove (5) to the top width s2 of the crown (4) as the relative groove width rs3. Then rh1 is calculated by the following formula: rh1=h1 / h; rh2 is calculated using the following formula: rh2 = h2 / (h - h1); rs1 is calculated using the following formula: rs1 = s1 / s; rs2 is calculated using the following formula: rs2 = s2 / s1; rs3 is calculated using the following formula: rs3 = s3 / s2.

5. The crown-shaped turbulence drag reduction microrib structure according to claim 4, characterized in that: The values ​​of s+ range from 10 to 30, rh ranges from 0.2 to 1, rh1 ranges from 0.5 to 0.8, rh2 ranges from 0.2 to 0.8, rs1 ranges from 0.3 to 0.5, rs2 ranges from 0.6 to 1, rs3 ranges from 0.4 to 0.8, a1 ranges from 20° to 60°, a2 ranges from 20° to 60°, and a3 ranges from 50° to 120°.

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