A NACA 0018 airfoil in freestream velocity is oscillated in longitudinal, transverse, and angle-of-attack directions with respect to the freestream velocity, known as surge, plunge, and pitch. The lift-based equivalence method introduces phase shifts between these three motions to construct in-phase sinusoidal components for maximum lift, waveform construction. Lift cancellation is also determined with the exact negative pitch and plunge motion amplitudes found from the equivalence method to achieve out-of-phase wave destruction. Lift cancellation occurs when a combination of these motions is sought to obtain a constant lift magnitude throughout the oscillation cycle. To achieve both equivalence and cancellation of lift, a prescribed pure pitch amplitude through the Theodorsen theory equates the corresponding equivalent plunge amplitude and pitch-plunge phase shift. These Theodorsen, linear superposition findings of pitch-plunge are leveraged toward the Greenberg theory to determine a closed-form, surge-pitch-plunge solution through the addition of a surge-plunge phase shift and optimal surge amplitude for lift cancellation. The lift cancellation surge-pitch-plunge amplitudes define the equivalence amplitude investigated here and theoretically limit the experiment to combinations of the first lift harmonic of the Greenberg theory. The analytical results are then compared with experimental lift force measurements and dye visualization. The normalized lift differences due to unsteady wake and boundary-layer behavior are examined to explore the extents of the Greenberg theory for these cases of lift-based equivalence and cancellation.
L o a d i n g
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National Renewable Energy Laboratory (NREL) - view all
Update frequencyunknown
Last updated4 days ago
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Overview00120018GreenbergHydrokineticLEVMHKMarineNACANACA 0018Quasi-SteadyTheodersenairfoilcancellationdye visualizationenergyequivalenceexperimentexperimentalfoil theorylab testleading-edge vortexliftlift-basednormalized liftoscillationphase shiftpitchpitch-plungeplungepowersurgesurge-pitch-plungesurge-plungetestwater tunnel
Additional Information
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Dcat Issued2020-01-01T07:00:00Z
Dcat Modified2021-01-14T17:27:40Z
Dcat Publisher NameNorth Carolina State University
Guidhttps://data.openei.org/submissions/7988
Harvest Object Idf43410c7-d85f-434b-a8fc-4ebe161064b2
Harvest Source Id4eb7107f-a2b1-40e3-b36a-8161aa98a56e
Harvest Source TitleOpenEI Data Portal
