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The effects of icing on the dynamic response of thick aerofoils

Published online by Cambridge University Press:  04 July 2016

C. A. Lucas
C. A. Lucas*
Affiliation:
Australian Artificial Intelligence Institute, Carlton, Australia
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Summary

Vibration of a flexible wing strut of 30% thickness/chord ratio occurred during icing trials of a commuter aircraft. This was caused by the formation of ice on the leading-edge of the strut producing a ‘double-horned’ ice shape. The two horns formed one above the other, having very sharp leading-edges with radii less than 0·6% of the strut chord of 0·23 m.

Wind tunnel testing demonstrated that, over a limited range of incidence angle, the flow around the flexible strut was dominated by a long separation bubble that periodically ‘burst’ and re-attached. This occurred at a reduced frequency of nominally 0·06, based upon the chord of the profile and the free stream velocity. The periodic flow was also spatially highly coherent, producing relatively large unsteady forces compared with the buffet forces generated by incoherent turbulent separated flows.

A high-speed film was made using smoke visualisation of the flow around a 40% rigid scale model of the strut. This was used to correlate the unsteady pressure field, measured at 18 points around the profile, with the dynamic behaviour of the separation bubble.

The periodicity was found to be inherent in the flows over both the flexible and rigid struts for a limited range of incidence, occurring even when structural response was restrained to a level below that at which lock-in occurred between the flow and the response motion. The peak value of the unsteady pressure was measured on the top surface of the upper ice horn. The root mean square value of 18% of the free stream dynamic pressure was measured, with response restrained to below the lock-in threshold.

Type
Research Article
Information
The Aeronautical Journal , Volume 95 , Issue 947 , September 1991 , pp. 231 - 240
Copyright
Copyright © Royal Aeronautical Society 1991 

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References

1. Bowden, D. T., Gensemer, A. E. and Skeen, C. A. Engineering Summary of Airframe Icing Technical Data. Federal Aviation Agency Tech. Rep. ADS-4, 1964.Google Scholar
2. Bell, J. D., Yeoman, K. E. Predicted Ice Shapes. Nomad N22B, Rev. A, 1977.Google Scholar
3. McCullough, G. B., Gault, D. E. Examples of Three Representative Types of Airfoil-Section Stall at Low Speed. NACA TN 2502, 1951.Google Scholar
4. Gault, D. E. A Correlation of Low-Speed Stalling Characteristics with Reynolds Number and Aerofoil Geometry. NACA TN 3963, 1957.Google Scholar
5. Chappel, P. D. Flow separation and stall characteristics of plane, constant-section wings in sub-critical flow. Aeronaut J, January 1968, 72, (685), pp 82–90.Google Scholar
6. Lucas, C. A. A Study of Wing Buffet. PhD Thesis, Cambridge University, 1977.Google Scholar
7. Lucas, C. A. Maull, D. J. The effects of aerofoil profile on wing buffet at low speeds. Aeronaut J, March 1990, 94, (933), pp 86–90.Google Scholar
8. Mabey, D. G., Ashill, P. R. and Welsh, B. L. Aeroelastic oscillations caused by transitional boundary layers and their attenuation. J Aircr, 1987, 24, (7), pp 463–469.Google Scholar
9. Mabey, D. G. Pressure Fluctuations caused by Separated Bubble Flows at Subsonic Speeds. RAE TR 71160, 1971.Google Scholar
10. Koopman, G. H. The vortex wakes of vibrating circular cylinders at low Reynolds numbers. J Fluid Mech, 1967, 28, Part 3, pp 501–512.Google Scholar
11. Powell, A., Schulman, J. Effects of wire resonance on aeolina tones. J Acoust Soc Am, 1962, 34, pp 1146–1147.Google Scholar
12. Protos, A., Goldschmidt, V. W. and Toebes, G. H. Hydroelastic forces on bluff cylinders. Trans J ASME Basic Eng, September 1968, 90, Series D, (3), pp 378–386.Google Scholar
13. Across-Flow Response due to Vortex Shedding: Isolated Circular Cylindrical Structures in Wind or Gas Flows. Engineering Sciences Data Unit No. 78006, Nov. 1980.Google Scholar
14. Fluctuating Loads and Dynamic Response of Bodies and Structures in Fluid Flows - Background Information. Engineering Sciences Data Unit, No. 77032, March 1978.Google Scholar
15. Bragg, M. B. Predicting rime ice accretion on airfoils. AIAA J, 1985, 23, (3), pp 381–387.Google Scholar
16. Atkins, P. B. Experimental Investigations of Aircraft Intake Icing, ARL Tech. Note to be published.Google Scholar
17. Wilder, R. Techniques Used to Determine Artificial Ice Shapes and Ice Shedding Characteristics of Unprotected Airfoil Surfaces. Presented at the FAA Symposium on Aircraft Ice Protection, Washington, DC, April 1969.Google Scholar