Oscillatory plunging motion applied to an airfoil near stall

Mark A. Agate, Jesse Little, Hermann Fasel, Andreas Gross

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

The effects of high frequency (k = 0.70), low amplitude (h = 3.2% and 4.8%) oscillatory plunging motion on the X-56A airfoil are examined at Re = 2.0 × 105using wind tunnel experiments and implicit large eddy simulations. The objective of this work is to understand the fundamental physics associated with laminar separation bubbles in an unsteady environment that is representative of the motion experienced by high aspect ratio wings. For a nominal angle of attack of 10◦ and a wing motion with k = 0.70 and h = 3.2%, the static CLmaxis exceeded by about 20% thus delaying lift stall (static stall occurs at 12.25°). The moment coefficient oscillates around the static values with only minor deviations. Experiments, simulations, and unsteady inviscid theory (Theodorsen) show only minor differences in this case. For a nominal angle of attack of 12° for a wing motion with k = 0.70 and h = 4.8%, the results begin to deviate largely from the inviscid theory. CLmaxis exceeded by about 32% and lift stall occurs at angles of attack far beyond static stall. However, a strong moment stall occurs due to a “bursting” of the laminar separation bubble just before the bottom of the oscillation cycle as the maximum acceleration is approached. These results are confirmed experimentally through surface pressure and particle image velocimetry data. The lift coefficient obtained from the simulation differs from the experimental lift coefficient due to subtle variations in the bubble shedding dynamics, but the qualitative behavior is very similar. Efforts to assess the influence of grid resolution on the observed discrepancies between the experiment and simulation are ongoing.

Original languageEnglish (US)
Title of host publicationAIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Electronic)9781624104473
DOIs
StatePublished - 2017
Event55th AIAA Aerospace Sciences Meeting - Grapevine, United States
Duration: Jan 9 2017Jan 13 2017

Publication series

NameAIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting

Other

Other55th AIAA Aerospace Sciences Meeting
CountryUnited States
CityGrapevine
Period1/9/171/13/17

ASJC Scopus subject areas

  • Aerospace Engineering

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    Agate, M. A., Little, J., Fasel, H., & Gross, A. (2017). Oscillatory plunging motion applied to an airfoil near stall. In AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting [AIAA 2017-0998] (AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting). American Institute of Aeronautics and Astronautics Inc.. https://doi.org/10.2514/6.2017-0998