Abstract
The effect of internal acoustic excitation on the leading-edge, separated boundary layers and the aerodynamic performance of NACA23015 cross section airfoil are examined as a function of excitation location with ranging frequency range (50-400) Hz of the introduced acoustic. Tests are separately conducted in two sections, open type wind tunnels at the Reynolds number of 3.3x105 for measurement at angle of attack (0, 3, 6, 9 &12) deg. and 3x104 for the visualization at angle of attack (12) deg. based on the airfoil chord. Results indicated that the excitation frequency and the excitation location are the key parameters to alter the flow properties and thus to improve the aerodynamic performance. The most effective excitation frequency is found to be equal to the shear layer instability frequency and on excitation location close to the separation point. Moreover, the lift is increased and drag reduced dramatically. The corresponding boundary layers are visualized to be reattached to the surface.
References
[2] Yarusevych S., J. G. Kawall & P.Sullivan , “Influence of Acoustic Excitation on Airfoil Performanc at Low Reynolds Numbers”, J.Fluids Engineering, Vol.128, 2006.
[3] Fei-Bin Hsiao, Chin-Fung Liu, and Jong-Yaw Shyut, "Control of Wall Separated Flow by Internal Acoustic Excitation", Aiaa Journal, Vol. 28, No. 8,1990.
[4] R. C. Change, F. B. Hsiao, R. N. Shyu, "Forcing Level Effects of Internal Acoustic Excitation on the Improvement of Airfoil Performance", Journal of Aircraft, Vol. 129, No. 5, Sep. - Oct. 1992.
[5] Hsiao F. B., J. J. Jihand and R. N. Shyn, “The Effect of Acoustics on Flow Passing A High-AOA Airfoil”, Journal of Sound and Vibration, Vol. 199, No.2, 1997.
[6] Naveh T, Seifert A, Wygnanski I. “Sweep Effect on Parameters Governing Control of Separation by Periodic excitation”, AlAA Journal, Vol. 35, No.3, 1998.
[7] Alan. P.J. and Harper, “ Low Speed Wind Tunnel Testing ” John Willey and
Sons. Int. 1966.
Copyright: Open Access authors retain the copyrights of their papers, and all open access articles are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided that the original work is properly cited. The use of general descriptive names, trade names, trademarks, and so forth in this publication, even if not specifically identified, does not imply that these names are not protected by the relevant laws and regulations. While the advice and information in this journal are believed to be true and accurate on the date of its going to press, neither the authors, the editors, nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.