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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