A V-shaped drag reduction structure and a straight pipe section with the V-shaped drag reduction structure

Abstract

A V-shaped drag reduction structure and a straight pipe section with the V-shaped drag reduction structure, comprising a first drag reduction section and a second drag reduction section coaxially communicated with each other and matched in interface structure, the first drag reduction section and the second drag reduction section are both hollow quadrangular prism structures with plane side walls, the opposite side surfaces of the first drag reduction section and the second drag reduction section are mirror-symmetric along the axis, and the interface of the first drag reduction section and the second drag reduction section is rectangular; the air inlet and the air outlet are rectangular structures equal in structure, the width of the air inlet is smaller than that of the interface of the first drag reduction section and the second drag reduction section, and the height of the air inlet is smaller than that of the interface of the first drag reduction section and the second drag reduction section. By the continuous V-shaped convex design, the sharp ridge line is utilized to actively induce the regular flow field structure, the near-wall velocity gradient is reduced, and the frictional resistance along the straight pipe section is reduced by more than 20%, the energy-saving effect is remarkable, the manufacturing process is simple, and the V-shaped drag reduction structure has a broad market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving technology for pipeline fluid transportation and distribution, specifically relating to a V-shaped drag-reducing structure and a straight pipe section with a V-shaped drag-reducing structure. Background Technology

[0002] Building energy consumption accounts for a significant portion of global energy consumption, representing more than one-third of the total. Among these, HVAC systems are particularly prominent, accounting for approximately 30% to 50% of total building energy consumption. As the core power equipment of this system, the energy consumption of fans is primarily used to overcome fluid flow resistance in duct systems. This resistance can be categorized into two types: one is local resistance loss caused by components such as tees, elbows, and reducers; the other is frictional resistance loss along straight pipe sections. Currently, much research focuses on optimizing local pipe components, while systematic research on flow resistance in straight pipe sections remains insufficient. Therefore, effectively reducing frictional resistance in straight pipe sections has significant engineering value and research implications for improving energy efficiency and achieving energy conservation and emission reduction goals.

[0003] Existing drag reduction technologies mainly focus on micro / nanoscale surface structures, such as constructing superhydrophobic surfaces, arranging microgroove structures, and biomimetic non-smooth surfaces. However, due to complex manufacturing processes, high costs, and insufficient durability in real operating environments, the large-scale application of these technologies in building ventilation duct systems still faces challenges. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a V-shaped drag reduction structure and a straight pipe section with the V-shaped drag reduction structure, thereby solving the drag reduction problem of the straight pipe section constituting the main body of the system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention includes: A V-shaped drag reduction structure includes a first drag reduction section and a second drag reduction section that are coaxially connected and have matching connecting surface structures. Both the first and second drag reduction sections are hollow quadrangular prism structures with planar sidewalls. The opposite sides of the first and second drag reduction sections are mirror-symmetrical along their axes, and the connecting surface between the first and second drag reduction sections is rectangular. The free ends of the first and second drag reduction sections are respectively an air inlet and an air outlet, which are rectangular structures with equal structures. The width of the air inlet is less than the width of the connecting surface between the first and second drag reduction sections, and the height of the air inlet is less than the height of the connecting surface between the first and second drag reduction sections.

[0006] Preferably, the length of the first drag reduction section axis L1 is greater than the length of the second drag reduction section axis L2.

[0007] Preferably, the total length of the axis of the first drag reduction section and the second drag reduction section is L, the value of L1 / L is in the range of 0.5~1 and not equal to 1, and the value of L2 / L is in the range of 0~0.5 and not equal to 0.

[0008] Preferably, L1 / L=0.8 and L2 / L=0.2.

[0009] Preferably, the height of the air inlet is H, and the height of the interface between the first and second drag-reducing sections is H+2h. h h h / H ranges from 0.05 to 0.15; the width of the air inlet is W, and the width of the interface between the first and second drag-reducing sections is W+2h. w h w The value of / W ranges from 0.05 to 0.15.

[0010] Preferably, h h / H=0.1, h w / W=0.1.

[0011] Preferably, the value of H is 120mm-630mm and the value of W is 160mm-1250mm.

[0012] Preferably, H is 200mm, W is 200mm, and L is 1200mm.

[0013] Preferably, the Reynolds number is 1.3 × 10⁻⁶. 5 ~2.4×10 5 .

[0014] A straight pipe section with a V-shaped drag reduction structure includes two coaxial pipes with identical structures. The pipes are hollow prisms with rectangular cross-sections. The pipe section also includes a V-shaped drag reduction structure coaxially connected between the two pipes. The V-shaped drag reduction structure is the V-shaped drag reduction structure disclosed in this application. The ports of the two pipes are matched with the air inlet and air outlet structures, and the inner cavity of the V-shaped drag reduction structure is connected to the inner cavities of the two pipes.

[0015] Compared with the prior art, the advantages of the present invention are: (1) A V-shaped drag reduction structure and a straight pipe section with a V-shaped drag reduction structure, through its continuous V-shaped protrusion design, utilizes its sharp edges to actively induce a regular flow field structure, reduce the near-wall velocity gradient, and thus significantly reduce friction loss along the pipe.

[0016] (2) A V-shaped drag reduction structure and a straight pipe section with a V-shaped drag reduction structure, by optimizing the duct wall, can reduce the frictional resistance along the straight pipe section by more than 20%, and achieve significant energy saving effect.

[0017] (3) A V-shaped drag reduction structure and a straight pipe section with a V-shaped drag reduction structure. The overall structure is based on macroscopic design and has the characteristics of regular geometric shape and clear boundary features. It is easy to achieve mass production through metal forming processes such as extrusion molding and molding or molding processes. While ensuring drag reduction effect, it also has excellent processing and manufacturing feasibility and has broad market application prospects. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0019] In the attached diagram: Figure 1 This is a schematic diagram of the V-shaped drag reduction structure of the present invention.

[0020] Figure 2 for Figure 1 Front view and geometric parameter diagram of the drag-reducing structure duct.

[0021] Figure 3 for Figure 1 Top view and geometric parameter diagram of the drag-reducing structure duct.

[0022] Figure 4 Comparison diagram of turbulent dissipation in Example 1 Figure 5 This is a comparison chart of friction drag coefficients at different Reynolds numbers for Comparative Example 2. The labels in the diagram represent: 1. Air inlet; 2. Air outlet; 3. V-shaped drag reduction structure, 3-1 first drag reduction section, 3-2 second drag reduction section. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are for illustrative purposes only and are not intended to limit the scope of the invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] Example 1 like Figure 1-3As shown, this embodiment discloses a V-shaped drag reduction structure, including a first drag reduction section 3-1 and a second drag reduction section 3-2 that are coaxially connected and have matching connecting surface structures. Both the first drag reduction section 3-1 and the second drag reduction section 3-2 are hollow quadrangular prism structures with flat sidewalls. The opposite sides of the first drag reduction section 3-1 and the second drag reduction section 3-2 are mirror-symmetrical along their axes, and the connecting surface between the first drag reduction section 3-1 and the second drag reduction section 3-2 is rectangular. The free ends of the first drag reduction section 3-1 and the second drag reduction section 3-2 are respectively an air inlet 1 and an air outlet 2. The air inlet 1 and the air outlet 2 are rectangular structures with equal structures. The width of the air inlet 1 is less than the width of the connecting surface between the first drag reduction section 3-1 and the second drag reduction section 3-2, and the height of the air inlet 1 is less than the height of the connecting surface between the first drag reduction section 3-1 and the second drag reduction section 3-2. Its function is as follows: Through its continuous V-shaped protrusion design, the whole structure actively induces a regular flow field structure by using its sharp edges, reducing the near-wall velocity gradient and thus significantly reducing friction loss. At the same time, the structure is based on macroscopic design and has the characteristics of regular geometry and clear boundary features, which makes it easy to achieve mass production through extrusion molding, compression molding and other processes, ensuring drag reduction effect while having excellent processing and manufacturing feasibility.

[0025] Specifically, the length L1 of the first drag-reducing section 3-1 is greater than the length L2 of the second drag-reducing section 3-2; the total length of the axes of the first drag-reducing section 3-1 and the second drag-reducing section 3-2 is L, the value of L1 / L is 0.5~1 and not equal to 1, the value of L2 / L is 0~0.5 and not equal to 0, and in this embodiment L1 / L=0.8 and L2 / L=0.2.

[0026] Specifically, the height of air inlet 1 is H, and the height of the interface between the first drag reduction section 3-1 and the second drag reduction section 3-2 is H+2h. h h h The value of / H ranges from 0.05 to 0.15; the width of the air inlet 1 is W, and the width of the interface between the first drag-reducing section 3-1 and the second drag-reducing section 3-2 is W+2h. w h w The value of / W ranges from 0.05 to 0.15; in this embodiment, h h / H=0.1, h w / W=0.1.

[0027] Specifically, H is 120mm-630mm and W is 160mm-1250mm; in this embodiment, H is 200mm, W is 200mm and L is 1200mm.

[0028] Specifically, the Reynolds number is 1.3 × 10⁻⁶. 5 ~2.4×10 5 In this embodiment, it is 1.7 × 105 .

[0029] Example 2 This embodiment discloses a straight pipe section with a V-shaped drag reduction structure, including two coaxial pipes with identical structures. The pipes are hollow prisms with rectangular cross-sections. The embodiment also includes a V-shaped drag reduction structure 3 coaxially connected between the two pipes. The V-shaped drag reduction structure 3 is the V-shaped drag reduction structure of Embodiment 1. The ports of the two pipes are matched with the structures of the air inlet 1 and the air outlet 2, and the inner cavity of the V-shaped drag reduction structure 3 is connected to the inner cavities of the two pipes.

[0030] Comparative Example 1 Energy dissipation analysis was performed on a conventional duct of the same size and the drag-reducing structure of the V-shaped straight duct section in Example 1.

[0031] The resistance to flow in a pipe originates from the irreversible dissipation of mechanical energy caused by the viscosity of the fluid. As flow proceeds, the total mechanical energy of the fluid decays as it is continuously converted into internal energy; this process can be precisely described by a dissipation function. Therefore, the core physical objective of reducing flow resistance lies in reducing the energy dissipation rate within the fluid through various methods.

[0032] Figure 4 This demonstrates the case where the Reynolds number is 1.7 × 10⁻⁶. 5 A comparison of turbulent dissipation rate cloud maps of the inner walls of the two types of ducts under this typical operating condition reveals that energy dissipation in ordinary ducts is relatively uniformly distributed in the flow field space and is widespread throughout the entire flow domain. Flow field analysis shows that the V-shaped drag-reducing structure, through its specific geometry, actively controls the near-wall turbulent structure. Energy dissipation is no longer uniformly distributed but highly concentrated at the beginning and end of the V-shaped drag-reducing structure; simultaneously, a stable secondary flow forms in the middle region of the drag-reducing structure, and the dissipation intensity is significantly reduced. This confirms that the structure achieves global drag reduction by guiding and localizing energy dissipation.

[0033] Comparative Example 2 To evaluate the drag reduction performance of the V-shaped drag-reducing duct of the present invention, at a Reynolds number of 1.3 × 10⁻⁶... 5 -2.4×10 5 Within the specified range, the friction coefficients of ordinary ducts of the same size and the V-shaped drag-reducing duct of this invention were compared. The results show that the friction coefficients of the straight duct sections of the V-shaped drag-reducing structure disclosed in this invention are significantly lower than those of ordinary ducts, exhibiting stable and wide drag-reduction adaptability. The maximum reduction in friction coefficient reaches 50.66%, demonstrating broad engineering application prospects and significant energy-saving and emission-reduction economic benefits.

[0034] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0035] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0036] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content invented by this disclosure.

Claims

1. A V-shaped drag-reducing structure, characterized in that, It includes a first drag-reducing section (3-1) and a second drag-reducing section (3-2) that are coaxially connected and have matching connecting surface structures. Both the first drag-reducing section (3-1) and the second drag-reducing section (3-2) are hollow quadrangular prism structures with flat sidewalls. The opposite sides of the first drag-reducing section (3-1) and the second drag-reducing section (3-2) are mirror symmetrical along their axes, and the connecting surface between the first drag-reducing section (3-1) and the second drag-reducing section (3-2) is rectangular. The free ends of the first drag reduction section (3-1) and the second drag reduction section (3-2) are respectively the air inlet (1) and the air outlet (2). The air inlet (1) and the air outlet (2) are rectangular with the same structure. The width of the air inlet (1) is less than the width of the connecting surface between the first drag reduction section (3-1) and the second drag reduction section (3-2), and the height of the air inlet (1) is less than the height of the connecting surface between the first drag reduction section (3-1) and the second drag reduction section (3-2).

2. The V-shaped drag-reducing structure as described in claim 1, characterized in that, The length L1 of the first drag reduction section (3-1) is greater than the length L2 of the second drag reduction section (3-2).

3. The V-shaped drag-reducing structure as described in claim 2, characterized in that, The total length of the axis of the first drag reduction section (3-1) and the second drag reduction section (3-2) is L. The value of L1 / L is in the range of 0.5~1 and not equal to 1, and the value of L2 / L is in the range of 0~0.5 and not equal to 0.

4. The V-shaped drag-reducing structure as described in claim 3, characterized in that, L1 / L=0.8, L2 / L=0.

2.

5. The V-shaped drag-reducing structure as described in any one of claims 1-4, characterized in that, The height of the air inlet (1) is H, and the height of the interface between the first drag-reducing section (3-1) and the second drag-reducing section (3-2) is H+2h. h h h The value of / H ranges from 0.05 to 0.15; the width of the air inlet (1) is W, and the width of the interface between the first drag-reducing section (3-1) and the second drag-reducing section (3-2) is W+2h. w h w The value of / W ranges from 0.05 to 0.

15.

6. The V-shaped drag-reducing structure as described in claim 5, characterized in that, h h / H=0.1,h w / W=0.1。 7. The V-shaped drag-reducing structure as described in claim 6, characterized in that, The value of H is 120mm-630mm, and the value of W is 160mm-1250mm.

8. The V-shaped drag-reducing structure as described in claim 7, characterized in that, H is 200mm, W is 200mm, and L is 1200mm.

9. The V-shaped drag-reducing structure as described in claim 8, characterized in that, The Reynolds number is 1.3 × 10⁻⁶. 5 ~2.4×10 5 .

10. A straight pipe section with a V-shaped drag-reducing structure, comprising two coaxial and identical pipes, wherein the pipes are hollow prisms with rectangular cross-sections, characterized in that, It also includes a V-shaped drag reduction structure (3) coaxially connected between the two pipelines, wherein the V-shaped drag reduction structure (3) is the V-shaped drag reduction structure according to any one of claims 1-9; The ports of the two pipelines are matched with the structures of the air inlet (1) and the air outlet (2), and the inner cavity of the V-shaped drag reduction structure (3) is connected to the inner cavity of the two pipelines.

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