0
TECHNICAL PAPERS

Airfoil Performance at Low Reynolds Numbers in the Presence of Periodic Disturbances

[+] Author and Article Information
S. Yarusevych1

 University of Toronto, Department of Mechanical and Industrial Engineering, 5 King’s College Rd., Toronto, Ontario, M5S 3G8, Canadayarus@mie.utoronto.ca

J. G. Kawall

 Ryerson University, Department of Mechanical and Industrial Engineering, 350 Victoria St., Toronto, Ontario, M5B 2K3, Canadagkawall@ryerson.ca

P. E. Sullivan

 University of Toronto, Department of Mechanical and Industrial Engineering, 5 King’s College Rd., Toronto, Ontario, M5S 3G8, Canadasullivan@mie.utoronto.ca

1

Corresponding author.

J. Fluids Eng 128(3), 587-595 (Oct 10, 2005) (9 pages) doi:10.1115/1.2175165 History: Received March 04, 2005; Revised October 10, 2005

The boundary-layer separation and wake structure of a NACA 0025 airfoil and the effect of external excitations in presence of structural vibrations on airfoil performance were studied experimentally. Wind tunnel experiments were carried out for three Reynolds numbers and three angles of attack, involving hot-wire measurements and complementary surface flow visualization. The results establish that external acoustic excitation at a particular frequency and appropriate amplitude suppresses or reduces the separation region and decreases the airfoil wake, i.e., produces an increase of the lift and∕or decrease of the drag. The acoustic excitation also alters characteristics of the vortical structures in the wake, decreasing the vortex length scale and coherency. Optimum excitation frequencies were found to correlate with the fundamental frequencies of the naturally amplified disturbances in the separated shear layer. The results suggest that acoustic waves play a dominant role in exciting the separated shear layer of the airfoil. Moreover, low-frequency structural vibrations are found to have a significant effect on airfoil performance, as they enhance the sound pressure levels within the test section.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Tunnel test section

Grahic Jump Location
Figure 2

Mean-velocity profiles, x∕c=1, α=10°

Grahic Jump Location
Figure 3

Euu spectra, x∕c=2

Grahic Jump Location
Figure 4

Evv spectra for Rec=150×103, x∕c=3

Grahic Jump Location
Figure 5

Test section resonance characteristics: (a) sound pressure and (b) airfoil surface acceleration

Grahic Jump Location
Figure 6

Separated shear layer spectra, α=10deg; vertical dashed lines indicate the margins of the effective frequency ranges

Grahic Jump Location
Figure 7

Effect of excitation on mean profiles for Rec=57×103, x∕c=2

Grahic Jump Location
Figure 8

Effect of excitation on mean profiles for Rec=100×103, x∕c=2

Grahic Jump Location
Figure 9

Effect of excitation on Evv spectra for Rec=57×103, x∕c=3

Grahic Jump Location
Figure 10

Effect of excitation on Evv spectra for Rec=100×103, x∕c=3

Grahic Jump Location
Figure 11

Effect of excitation on Evv spectrum for Rec=150×103 at α=10°, x∕c=3

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In