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Control of Delta-Wing Vortex by Apex Strake
Myong Hwan Sohn,Hyoung Seog Chung 한국항공우주학회 2007 International Journal of Aeronautical and Space Sc Vol.8 No.2
The vortex flow characteristics of a double-delta wing, which can change the incidence angle of its apex strake was investigated through the wing-surface pressure measurement and the particle image velocimetry(PIV) measurement of the wing-leeward flow region. The apex strake has sharp edges and can change its incidence angle with a hinge line at the 23% chord position measured from the apex of the main wing. The present study revealed that the incidence-angle change of the apex strake could greatly alter the vortex flow pattern around the double-delta wing and the wing-surface pressure distribution, which suggested that the apex strake could be used as an effective device for the active control of delta-wing vortex flow.
Control of Delta-Wing Vortex by Micro-Fin-Type Leading-Edge Flap
Myong Hwan Sohn,Hyoung Seog Chung,Dong Hyun Cho 한국항공우주학회 2006 International Journal of Aeronautical and Space Sc Vol.7 No.2
The present study examined the effects of micro leading-edge flaps on the vortex characteristic changes of a double-delta wing through pressure measurements of the wing upper surface and PIV measurements of the wing-leeward flow region. The experimental data were collected and analyzed while changing the deflection angle of the leading-edge flaps to investigate the feasibility of using micro leading-edge flaps as flow control devices. The test results revealed that the leading edge modification could greatly alter the vortex flow pattern and the wing surface pressure of the delta wing, which suggested that the leading-edge flaps could be used as an effective device for the control of delta-wing vortex flow.
Sohn, Myong Hwan,Lim, Seungmin,Seo, Kyung Won,Lee, Sang Joon Oxford University Press 2013 Journal of plankton research Vol.35 No.6
<P>The effect of ambient medium viscosity on the motility and flagellar beating motion of the dinoflagellate <I>Prorocentrum minimum</I> was experimentally investigated. <I>Prorocentrum minimum</I> is a thecate desmokont dinoflagellate with two flagella that emerge from the flagellar pore at the anterior end of the cell. A digital holographic particle tracking velocimetry technique was employed to capture the swimming trajectories of hundreds of <I>P. minimum</I> cells and to extract the kinematic motion parameters. The viscosity of the surrounding medium was changed from 1.12 cP (natural sea water at 22°C) to 11.31 cP by adding methylcellulose to increase fluid viscosity. In natural sea water, the swimming speeds of <I>P. minimum</I> cells (<I>n</I> = 77) in a helical motion ranged from 5.4 to 138.4 µm/s with a mean speed of 51.3 ± 27.9 µm/s. The helix radius and pitch of the swimming trajectories are 3.08 ± 0.64 and 25.34 ± 7.96 µm/s, respectively. The longitudinal flagellum beats with a planar wave at a beating frequency of 87.10 ± 10.96 Hz. On the other hand, the transverse flagellum beats with a helical wave at a beating frequency of 45.38 ± 13.61 Hz. As the ambient medium viscosity increases, the beating frequency of flagella decreased and consequently, the swimming speed of <I>P. minimum</I> was reduced.</P>
Control of Delta-Wing Vortex by Micro-Fin-Type Leading-Edge Flap
Sohn, Myong-Hwan,Chung, Hyoung-Seog,Cho, Dong-Hyun The Korean Society for Aeronautical and Space Scie 2006 International Journal of Aeronautical and Space Sc Vol.7 No.2
The present study examined the effects of micro leading-edge flaps on the vortex characteristic changes of a double-delta wing through pressure measurements of the wing upper surface and PIV measurements of the wing-leeward flow region. The experimental data were collected and analyzed while changing the deflection angle of the leading-edge flaps to investigate the feasibility of using micro leading-edge flaps as flow control devices. The test results revealed that the leading edge modification could greatly alter the vortex flow pattern and the wing surface pressure of the delta wing, which suggested that the leading-edge flaps could be used as an effective device for the control of delta-wing vortex flow.
Visualization and Flowfield Measurements of the Vortical Flow over a Double-Delta Wing
Sohn, Myong-Hwan,Jang, Young-IL The Korean Society for Aeronautical and Space Scie 2003 International Journal of Aeronautical and Space Sc Vol.4 No.1
The vortical flow of a 65-deg flat plate delta wing with a leading edge extension(LEX) was examined through off-surface visualization, 5-hole probe and hot-film measurements. The off-surface flow visualization technique used micro water droplets generated by a home-style ultrasonic humidifier and a laser beam sheet. The angles of attack ranged from 10 to 30 degrees, and the sideslip angles ranged from 0 to -15 degrees. The Reynolds number was $1.82{\times}10^5$ for the flow visualization, and $1.76{\times}10^6$ for the 5-hole probe and hot-film measurements. The comparison of the visualization photos and the flow field measurement showed that the two results were in a good agreement for the relative position and the structure of the wing and LEX vortices, even though the flow Reynolds numbers of the two results were much different. The wing vortex and the LEX vortex coil each other while maintaining a comparable strength and identity at zero sideslip. Neither a looping of the wing vortex around the strake vortex, nor the lopsided coiling of the stronger strake and the weaker wing vortices was observed. At non-zero sideslip, the downward movement of the LEX vortex when going downstream was enhanced on the windward side, and the downward and inboard movement of the LEX vortex when going downstream was suppressed on the leeward side. The counterclockwise coiling of the wing and LEX vortices was decreased significantly on the leeward side.
Control of Delta-Wing Vortex by Apex Strake
Sohn, Myong-Hwan,Chung, Hyoung-Seog The Korean Society for Aeronautical and Space Scie 2007 International Journal of Aeronautical and Space Sc Vol.8 No.2
The vortex flow characteristics of a double-delta wing, which can change the incidence angle of its apex strake was investigated through the wing-surface pressure measurement and the particle image velocimetry(PIV) measurement of the wing-leeward flow region. The apex strake has sharp edges and can change its incidence angle with a hinge line at the 23% chord position measured from the apex of the main wing. The present study revealed that the incidence-angle change of the apex strake could greatly alter the vortex flow pattern around the double-delta wing and the wing-surface pressure distribution, which suggested that the apex strake could be used as an effective device for the active control of delta-wing vortex flow.