Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations

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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.

Citation Formats

North Carolina State University. (2020). Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations [data set]. Retrieved from https://mhkdr.openei.org/submissions/348.
Export Citation to RIS
Elfering, Kelsey, Granlund, Kenneth. Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations. United States: N.p., 01 Jan, 2020. Web. https://mhkdr.openei.org/submissions/348.
Elfering, Kelsey, Granlund, Kenneth. Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations. United States. https://mhkdr.openei.org/submissions/348
Elfering, Kelsey, Granlund, Kenneth. 2020. "Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations". United States. https://mhkdr.openei.org/submissions/348.
@div{oedi_348, title = {Lift Equivalence and Cancellation for Airfoil Surge-Pitch-Plunge Oscillations}, author = {Elfering, Kelsey, Granlund, Kenneth.}, abstractNote = {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.}, doi = {}, url = {https://mhkdr.openei.org/submissions/348}, journal = {}, number = , volume = , place = {United States}, year = {2020}, month = {01}}

Details

Data from Jan 1, 2020

Last updated Jan 14, 2021

Submitted Dec 4, 2020

Organization

North Carolina State University

Contact

Chris Vermillion

919.515.5244

Authors

Kelsey Elfering

North Carolina State University

Kenneth Granlund

North Carolina State University

DOE Project Details

Project Name Device Design and Robust Periodic Motion Control of an Ocean Kite System for Marine Hydrokinetic Energy Harvesting

Project Lead Carrie Noonan

Project Number EE0008635

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