@article{bd58efb81708474881b98deb04200c20,
title = "Numerical simulation of plunging wing section at high angles of attack",
abstract = "In the near-stall regime, the shedding of coherent structures can result in large unsteady aerodynamic loads. Under such conditions, high-aspect-ratio wings will experience some degree of structural motion. Simulations and experiments for a chord-based Reynolds number of Re = 200;000 are carried out for a wing section with an X-56A airfoil to investigate the effect of a harmonic heaving/plunging motion on the unsteady aerodynamics. The reduced frequency of the structural motion is 0.35 < k < 1.4, and the amplitude is 3.2-9.6% based on chord length. For a plunging motion at a 10 deg mean angle of attack, the unsteady lift is in good agreement with the Theodorsen theory. As the mean angle of attack is increased up to 14 deg, the flow begins to separate intermittently from the suction side of the wing. The onset of flow separation and the shedding of the resultant stall vortex depend on the frequency and amplitude of the structural motion. Steady spanwise disturbances that are introduced at the leading edge are found to strengthen the stall vortex. For a 16 deg angle of attack, the wing section is fully stalled. However, when subjected to a low-amplitude plunging motion, the flow intermittently reattaches and the mean lift is increased.",
author = "A. Gross and M. Agate and J. Little and Fasel, {H. F.}",
note = "Funding Information: This research was funded by the U.S. Air Force Office of Scientific Research under grant number FA9550-14-1-0184, with Douglas Smith serving as Program Manager. High Performance Computing (HPC) resources were provided by the U.S. Department of Defense (DOD) HPC Modernization Program. Additionally, this research was conducted with government support under and awarded by the DOD, U.S. Air Force Office of Scientific Research, National Defense Science and Engineering Graduate Fellowship (32 CFR 168a). Funding Information: With support from the U.S. Air Force Office of Scientific Research, a multitiered collaborative research project has been executed at the University of Arizona (UA) and the New Mexico State University (NMSU) to investigate the flow physics of wing sections undergoing structural motions that are typical for high-aspect-ratio aircraft. When the primary wing bending mode was excited, the wing was undergoing a heaving/plunging motion normal to the chord line at a relatively low reduced frequency and low amplitude. Scaled model flight experiments and wind-tunnel experiments (UA), as well as simulations (UA and NMSU), were carried out in a synergistic manner where the flight experiments provided the relevant parameter space (frequency and amplitude of wing motion) for the wind-tunnel experiments and simulations. The airfoil of the X-56A was chosen for this combined research program. The X-56A Multi-Utility Technology Testbed was designed as a flight platform for investigating the active flutter control of lightweight flexible structures [1]. Publisher Copyright: {\textcopyright} 2018 by the American Institute of Aeronautics and Astronautics, Inc.",
year = "2018",
doi = "10.2514/1.J056763",
language = "English (US)",
volume = "56",
pages = "2514--2527",
journal = "AIAA Journal",
issn = "0001-1452",
publisher = "American Institute of Aeronautics and Astronautics Inc. (AIAA)",
number = "7",
}