Simulation of Microbubbles Drag Reduction on Nonsmooth Surface with Hydrophobic Property

Abstract:

The friction resistance accounts for a large proportion of the total resistance, during the navigation of ships and underwater vehicles. Drag reduction techniques can significantly reduce the friction resistance of the wall and improve the speed of navigation. This paper combine microbubbles drag reduction technology and nonsmooth and hydrophobic surface technology. Building different analysis models, considering the dimples size of nonsmooth surface , the contact angle of surface and wall roughness, study the law between drag reduction and parameters of the wall by gas-liquid two-phase flow model. Under the same conditions, analysis results show that the performance of drag reduction is mainly determined by the dimple size of nonsmooth surface. The lager dimples cause stronger turbulence and loss more energy. The drag reduction effect is declined. There is a linear relationship between the drag reduction and the contact angle of hydrophobic surface. The drag reduction is enhanced by increasing the contact angle. But the principle is complicated between drag reduction and the roughness of the wall. There are different roughness to achieve the best effect under different flow velocities.

• Periodical: Applied Mechanics and Materials (Volumes 300-301)
• Pages: 3-9
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.300-301.3
• Online since: February 2013
• Authors: Ya Lun Hu, Zheng Li, Zhong Xu
• Keywords: Contact Angle of Hydrophobic, Micro-Bubble, Nonsmooth Surface, Roughness

References

[1] Huang Yangshun, Wang Zhen, Wang Jiqiang, Trends in research of drag reduction by micro-bubbles controlling turbulent boundary layer, Ship Engineering, 2003, 25(1).

[2] Cao Huizhe, Cai Weihua, Zhu Mengsheng, Gao Jieqiang, Li Biao, The numerical simulation of the microbubbles drag reduction in the bottom of two-dimensional approximate ship model, Energy Conservation Technology, 2010, 483-487.

[3] Dunischev Yu, Evseev A. R, Sobolev V. S, Utkin E. N, Study of gas-saturated turbulent streams using a laser-doper velocimeter, J. Appl. Mech. Tech. Phys. 16, No. 1, 1975, 16(1): 114.

DOI: 10.1007/bf00853551

[4] Madavan N. K, Deutch S, Merkle C. L, Reduction of turbulent skin-friction by microbubbles, Physics of Fluids, 1984, 27(2): 356-363.

DOI: 10.1063/1.864620

[5] Silberman E, Production of bubbles by the disintegration of gas jets in liquid, Proceedings of the 5th Mdiwestern Conference on Fluid Mechanics, University of Michigan, 1957, 263-284.

[6] Wang Jiamei, Jiang Mansong, Zheng Xiaowei, Zhan Dexin, Study of drag reduction of vessel model by microbubble with different injection forms in the towing basin, J. Huazhong Univ. Of Sci. and Tech., Dec. 2004, 78-80.

[7] Dong Wencai, Guo Rixiu, State of the art of research on resistance reduction by bubbly layer, Ship Building of China, 1998, 100-106.

[8] Hughes N. J, Reischman M. M, Holzman J. M, Digital image analysis of two phase flow data, Proceedings of the 6th Biennial Symposium on Turbulence, University of Missouri, (1979).