Vortex Wake Development and Aircraft Dynamics

  • J. E. Hackett
  • J. G. Theisen


The written paper describes and augments material delivered semiformally in Session III of the Symposium, as commentary to a movie. The computed aircraft response results were reported at the end of Session VI of the Symposium.

Calculations of the sinuous instability of a trailing pair are extended, using a nonlinear vortex modeling technique, and the effects of initial parameters are examined, particularly the ini­tially assumed wavelength. Realistic-looking tresses obtained were demonstrated using computer graphics.

More complex modes of vortex decay may be demonstrated by flow visualization in water, using the hydrogen bubble technique. Vortex bursting is shown to be possible before and/or after the “wavy” mode. These small-scale measurements are shown to be consistent with flight measurements.

In another series of experiments, smoke injected into the core of the trailing vortex behind a 13-foot-span C-130 wind-tunnel model, mounted in a 23-foot by 16-foot working section, showed remarkable coherence until the adverse pressure gradient in the wind-tunnel diffuser caused vortex bursting. The effects, on vortex burst posi­tion in the diffuser, of auxiliary blowing into or near the vortex core are discussed qualitatively.

The results of a computer simulation are discussed concerning the dynamic response and loads induced on an aircraft which enters the trailing vortex of a lead aircraft of large size. In the study, McCormick’s or Owen’s semi-empirical theories were judged as preferable for vortex decay estimates with distance behind the aircraft. However, the simulation results were only available using vortex core magnitudes from classical theory. The calcu­lated normal load factors and maximum angular motions (with and without control) were close to those reported for recent FAA and NASA tests with a CV-990 or DC-8 flying into the wake of a DC-9 or a jumbo jet.


Vortex Ring Vortex Core Lift Coefficient Roll Angle Vortex Pair 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Crow, S. C., “Stability Theory for a Pair of Trailing Vortices,” B.S.R.L. Document D1–82–0918.Google Scholar
  2. 2.
    Bisgood, P. L., Maltby, R. L., and Dee, F. W., “Some Work on the Behavior of Vortex Wakes at the Royal Aircraft Establishment,” Paper presented in Session IV of the 1970 Aircraft Wake-Turbulence Symposium.Google Scholar
  3. 3.
    Parks, P. C., “A New Look at Vortex Dynamics,” Paper presented in Session V of the 1970 Aircraft Wake Turbulence Symposium.Google Scholar
  4. 4.
    Hackett, J. E., and Evans, M. R., “Vortex Wakes behind High Lift Wings,” AIAA Paper 69–740, 1969.Google Scholar
  5. 5.
    Owen, P. R., “The Decay of a Turbulent Trailing Vortex,” The Aeronautical Quarterly, February 1970, pp. 69–78.Google Scholar
  6. 6.
    Scruggs, R. M., and Marris, A. W., “Axial Periodicity in Vortices,” Lockheed-Georgia Research Memorandum ER-9098, 1968.Google Scholar
  7. 7.
    Theisen, J. G., “Vortex Periodicity in Wakes,” AIAA Paper No. 67–34, 1967.Google Scholar
  8. 8.
    Scorer, R. S., “Local Instability in Curved Flow,” Journal of Fluid Mechanics, Vol. 25, Part 3, pp. 557–576.Google Scholar
  9. 9.
    Piercy, N. A. V., Aerodynamics, English Universities Press, Ltd., London, England, 2nd Ed., 1947.Google Scholar
  10. 10.
    Theisen, J. G., “V/STOL Stability and Control in Turbulence,” AMS/AIAA Paper at National Aerospace Meteorology Conference, New Orleans, Louisiana, May 1968.Google Scholar
  11. 11.
    Theisen, J. G., and Haas, J., “Turbulence Upset and Other Studies on Jet Transport Aircraft,” Journal of Aircraft, July-Aug. 1969.Google Scholar
  12. 12.
    McCormick, B. W., Tangier, J. L., and Sherrieb, H. E., “Structure of Trailing Vortices,” Journal of Aircraft, May-June 1968.Google Scholar
  13. 13.
    Boswinkle, R. W., “Vortex Wake Turbulence,” Paper presented at the Flight Safety Foundation 23rd International Air Safety Seminar, Washington, D. C., October 1970.Google Scholar

Copyright information

© Plenum Press, New York 1971

Authors and Affiliations

  • J. E. Hackett
    • 1
  • J. G. Theisen
    • 1
  1. 1.Lockheed-Georgia CompanyUSA

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