Publisher : The Society of Naval Architects of Korea
DOI : 10.3744/SNAK.2015.52.4.356
Title & Authors
Visualization of Microbubbles Affecting Drag Reduction in Turbulent Boundary Layer Paik, Bu-Geun; Yim, Geun-Tae; Kim, Kwang-Soo; Kim, Kyoung-Youl; Kim, Yoo-Chul;
Microbubbles moving in the turbulent boundary layer are visualized and investigated in the point of frictional drag reduction. The turbulent boundary layer is formed beneath the surface of the 2-D flat plate located in the tunnel test section. The microbubble generator produces mean bubble diameter of 30 – 50 μm. To capture the micro-bubbles passing through the tiny measurement area of 5.6 mm2 to 200 mm2, the shadowgraphy system is employed appropriately to illuminate bubbles. The velocity field of bubbles reveals that Reynolds stress is reduced in the boundary layer by microbubbles’ activity. To understand the contribution of microbubbles to the drag reduction rate more, much smaller field-of-view is required to visualize the bubble behaviors and to find the 2-D void fraction in the inner boundary layer.
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Jacob, B. Olivieri, A. Campana, E.F. & Piva, R., 2010. Drag Reduction by Microbubbles in a Turbulent Boundary Layer. Physics of Fluids, 22, pp.115104-11.
Kim, D.S. Kim, H.T. & Kim, W.J., 2003. Experimental Study of Friction Drag Reduction in Turbulent Flow with Microbubble Injection. Journal of the Society of Naval Architects of Korea, 40(3), pp.1-8.
Kim, J. Moin, P. & Moser R., 1987. Turbulence Statistics in Fully Developed Channel Flow at Low Reynolds number. Journal of Fluids Mechanics, 177, pp.133-166.
Kim, J.H. Oh, J.Y. Seo, D.W. & Lee, S.H., 2011. A Study on the Characteristics of an Air Cavity Attached under a Flat Plate. Journal of the Society of Naval Architects of Korea, 48(5), pp.396-403.
Paik, B.G. Kim, K.Y. & Ahn, J.W., 2009. Measurements of High Velocity Gradient Flow using Bubble Tracers in a Cavitation Tunnel. Journal of Fluids Engineering, 131, pp.091301.
Paik, B.G. Kim, K.Y. Cho, S.R. Ahn, J.W. Cho, S.R. Kim, K.R. & Chung, Y.U., 2013. Study on the Drag Performance of the Flat Plates Treated by Antifouling Paints. Journal of the Society of Naval Architects of Korea, 50(6), pp.399-406.