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ISSN Druckformat: 1065-3090
ISSN Online: 1940-4336
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A VISUALIZATION STUDY OF TIP VORTEX ROLL-UP OF AN OSCILLATING WING
ABSTRAKT
A flow visualization study was made to examine qualitatively the unsteady wing-tip vortex roll-up of an oscillating wing. A rectangular wing of aspect ratio 4 with NACA 0012 airfoil cross-section was mounted on one side of the wind tunnel wall, and the wing was pitched sinusoidally about the quarter chord. Both the mean incidence and the amplitude of oscillation were set at 15°. The reduced frequency of the oscillation was 0.09. Visualized flow patterns both in streamwise and in cross-sectional planes with smoke wire and light sheet arrangement are presented. The vortical flow pattern at various angles of attack clearly demonstrates the periodic vortex roll-up behavior. When the wing is in pitch-up motion, the flow remains attached to the wing, whereas the flow becomes separated during the pitch-down motion. The visualized vortex cores during the pitch-up motion are thus well defined and regular. On the contrary, the vortex cores during the pitch-down motion are of irregular shape, reflecting the roll-up from the separated flow. With reference to the tip-vortex strength (i.e., the circulation) data, the size of the visualized vortex core is seen to increase with the strength of the vortex for both pitch-up and pitch-down cases.
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Chang Jo Won, Yoon Yong Hyun, Eun Hee-bong, Near-Wake Characteristics of an Oscillating NACA 4412 Airfoil, 21st AIAA Applied Aerodynamics Conference, 2003. Crossref
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Chang Jo Won, Eun HeeBong, Reduced frequency effects on the near-wake of an oscillating elliptic airfoil, KSME International Journal, 17, 8, 2003. Crossref
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Chang Jo Won, Near-Wake Characteristics of an Oscillating NACA 4412 Airfoil, Journal of Aircraft, 41, 5, 2004. Crossref
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Luo S. C., Lua K. B., Goh E. K. R., Side Force on an Ogive Cylinder: Effects of Surface Roughness, Journal of Aircraft, 39, 4, 2002. Crossref
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Yoon Y., Chang J., Tan M., Camber effects in the near-wake of oscillating airfoils, 40th AIAA Aerospace Sciences Meeting & Exhibit, 2002. Crossref
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Chang Jo Won, Park Seung O., Measurements in the Tip Vortex Roll-Up Region of an Oscillating Wing, AIAA Journal, 38, 6, 2000. Crossref
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Chang Jo Won, Yoon Yong Hyun, Camber Effects on the Near Wake of Oscillating Airfoils, Journal of Aircraft, 39, 4, 2002. Crossref
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Lee Jeonghan, Cho Kyungseok, Lee Soogab, Application of Acoustic Analogy to Automotive Engine-Cooling Fan Noise Prediction, AIAA Journal, 38, 6, 2000. Crossref