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Load control is the reduction of extreme aerodynamic forces to enable lighter, more efficient aircraft. Current load control technologies are limited to low frequency disturbances. In this paper the mini-tab, a small, span-wise tab placed on the airfoil upper surface, is investigated as a high frequency alternative through periodic oscillations to identify its unsteady aerodynamic transfer function. Force measurements were conducted on a NACA0012 airfoil at a Reynolds number of 6.6x105 with a deployable mini-tab located at xf/c = 0.85, with actuation performed at reduced frequencies, k ≤ 0.79. The force measurements indicate that the mini-tab has a decreasing effect on lift reduction with increasing actuation frequency. This trend is comparable to Theodorsen’s function, based on the change in circulation. For α = 0°, the normalized peak-to-peak lift reduction decreased from 1 for steady state deployment to around 0.6 at k = 0.79. In addition, a phase lag exists between the mini-tab deployment and the aerodynamic response which increased with actuation reduced frequency, k. However, the measured phase lag is substantially larger than Theodorsen’s prediction. Increasing the angle of attack, α reduced the mini-tab’s effect on lift while increasing the phase angle when comparing equal k values. Particle Image Velocimetry measurements indicate that the delay and reduction in effectiveness of periodic deployment is due to the presence and growth of the separated region behind the mini-tab. Overall, the mini-tab was found to be an effective, dynamic lift reduction device with the separated region behind the mini-tab key to the amplitude and phase delay of lift response.
|Title of host publication
|55th AIAA Aerospace Sciences Meeting, 2017
|American Institute of Aeronautics and Astronautics
|Published - 11 Jan 2017
|55th AIAA Aerospace Sciences Meeting: AiAA SciTech 2017 - Gaylord Texan, Grapevine, Texas, USA United States
Duration: 9 Jan 2017 → 13 Jan 2017
|55th AIAA Aerospace Sciences Meeting
|USA United States
|9/01/17 → 13/01/17
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- 1 Finished
1/04/15 → 1/10/20
Project: Research council