FLOW INDUCED NOISE & CAVITATION CONTROL LAB.

AUTHENTIC DISCOVERY OF CAVITATION

RECENT ACHIEVEMENTS

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01 Bubbly Flow by Air Injection on an Inclined Hydrofoil

Physics of Fluids 33, 042209; DOI: 10.1063/5.0043221

Flow features resulting from air injection through a hole on an inclined hydrofoil in a free stream flow are investigated. The hydrofoil was oriented at different angles of inclination in the test section at the free stream velocity, 3, 5 and 7 m/s (Fn=30~70). The air jet emanating from the hole at various air injection rates (Cq) was characterized by high-speed imaging. Geometric features of the air jet, such as jet width, angle, effective diameter and thickness are measured from the high-speed images. Depending on Fn and Cq, several jet domains such as unstable jet, cloudy puff, buoyant-bifurcating jet, and stable-buoyant jet domains were observed upon air injection at Rn~1000 for various hydrofoil inclinations.

02 Experimental Investigation of Artificial Supercavitation

Physics of Fluids 31, 052106; DOI: 10.1063/1.5092542

Experimental investigation on drag characteristics and flow physics of ventilated supercavitating objects with different body shapes were conducted. The test model consists of a disk-type cavitator with two different fore bodies (slender and blunt shape) and three different rear bodies (flat, shrinkage, and expanded shape). The drag forces acting on different body-combinations in fully wetted conditions are measured and the results show that the drag coefficients strongly depend on the body shapes. It explains in detail through particle image velocimetry measurements. The drag characteristics are systematically examined over a broad range of ventilation rates.

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03 Coherent Structure of Turbulent Cavitating Flow

Fluids, 5(4) (invited paper); DOI: 10.3390/fluids5040198

In many practical submerged objects, various types of cavitation such as bubble, sheet, and cloud cavitation occur according to flow conditions. In this work, the series process consisting of inception, growth, and desinence of the partial cavity was investigated, and also noise generated during the process was also measured. The results show that the periodic behavior of cavitation clouds is directly reflected in the noise characteristics. In addition, the visualization of coherent structures within the sheet and cloud cavity provides a qualitative understanding of hairpin vortices and their packets, which play a dominant role in turbulent cavitating flows.

RESEARCH AREAS

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Dept. of Naval Architecture and Ocean Engineering, College of Engineering, Chungnam National University,

99 Daehak-ro, Yuseong-gu, Daejon, 34134, KOREA