﻿ 仿生鲨鱼皮滚压成型表面减阻数值模拟研究 Study on Numerical Simulation of Drug Reduction on the Bionic Surface of Shark Skin Fabricated by Roller Embossing

Modeling and Simulation
Vol.07 No.02(2018), Article ID:25202,13 pages
10.12677/MOS.2018.72009

Study on Numerical Simulation of Drug Reduction on the Bionic Surface of Shark Skin Fabricated by Roller Embossing

Xuefeng Yang, Danyang Zhao*

School of Mechanical Engineering, Dalian University of Technology, Dalian Liaoning

Received: May 5th, 2018; accepted: May 23rd, 2018; published: May 30th, 2018

ABSTRACT

U-shaped riblet could be pressed on the polymer films by wire winding roller embossing. In the process, the size and structure characteristic of micro-riblets are significantly influenced by the embossing deformation process parameters and the diameter of stainless steel wires. The numerical simulation of micro-riblet drag reduction has also been performed on basis of the riblets obtained by roll-to-roll embossing process. And the influence of micro-riblet size and structure on turbulent drag reduction has been revealed in three-dimensional incompressible turbulent flow. We find the turbulent drag reduction could be achieved when the micro-riblet size is small enough in the simulation. When the diameter of the micro-riblet is 0.02 mm, the drag reduction rate could be up to 10%. The influence of external interference on micro-riblet drag reduction is further studied by adding turbulence through a vortex generator and it intuitively shows vortex structure on micro-riblet also affects drag reduction. The micro-riblet drag reduction effect is more obvious when the flow is under the interference of turbulence.

Keywords:Wire Winding, Roller Embossing, Micro-Riblet Structure, Drag Reduction, Vortex Structure

1. 引言

2. 微沟槽结构的确定

2.1. 滚压成型

2.2. 流体域网格的划分

2.3. 边界条件的设置

1) 流体域的入口设置为速度入口；

2) 流体域的出口设置为自由流出口；

Figure 1. Schematic of roller embossing

Figure 2. The fluid domain

Figure 3. Grid distribution of computing domain

3) 流体域的其他壁面设置为无滑移壁面条件。

3. 减阻数值模拟及结果分析

${R}_{e}=\frac{v{d}_{H}}{\upsilon }$ (1)

$\eta =\frac{{F}_{s}-{F}_{g}}{{F}_{s}}×100%$ (2)

3.1. 理想型微沟槽结构的减阻模拟

Table 1. The states of flow field

Figure 4. Contrast curves of wall shear stress and wall frictional resistance on smooth surface and riblet surface

3.2. 实际成型微沟槽结构的减阻模拟

Figure 5. Drag reduction rate of semicircular riblets with different diameters

Figure 6. Distribution of shear stress on smooth surface and riblet surface

(a) (b)

Figure 7. Velocity vector diagram on smooth surface and riblet surface. (a) Smooth surface; (b) Riblet surface

Figure 8. Embossing results on polymer films

Figure 9. Contrast curves of wall shear stress and wall frictional resistance

Figure 10. Drag reduction rate of riblet surface with different depths

0.33、0.41和0.5时，沟槽面表现出了增阻的效果，并且都随着流速的增加，阻力增加越大，深宽比越大，阻力增加越大，最大增阻43%。

Figure 11. Distribution of shear stress on smooth surface and riblet surface

(a)(b)

Figure 12. Velocity vector diagram on smooth surface and riblet surface. (a) Smooth surface; (b) Riblet surface

3.3. 带有涡发生器的微沟槽结构的减阻模拟

Figure 13. Computing domain with vortex generator

Figure 14. Contrast curves of wall shear stress and wall frictional resistance

3.4. 减阻机理分析

Figure 15. Drag reduction rate of riblet surface with different depth

Figure 16. Contrast curves of wall shear stress and wall frictional resistance

(a) (b)

Figure 17. Velocity vector diagram on smooth surface and riblet surface. (a) Smooth surface; (b) Riblet surface

4. 结论

Study on Numerical Simulation of Drug Reduction on the Bionic Surface of Shark Skin Fabricated by Roller Embossing[J]. 建模与仿真, 2018, 07(02): 63-75. https://doi.org/10.12677/MOS.2018.72009

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NOTES

*通讯作者