Experimental investigation of counter-rotating four vortex aircraft wake

Alexander Allen, Christian Breitsamter

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


An experimental investigation on the wake vortex formation and evolution of a four vortex system of a generic model in the near field and extended near field as well as the behaviour and decay in the far field region has been conducted by means of hot-wire anemometry in a wind tunnel. The results were obtained during an experimental campaign as part of the EC project "FAR-Wake". The model used consists of a wing-tail plane configuration with the wing producing positive lift and the tail plane negative lift. The circulation ratio of tail plane to wing is -0.3 and the span ratio is 0.3. Thus, a four vortex system with counter-rotating neighboured vortices exists. The model set-up was chosen on the condition to create a most promising four vortex system with respect to accelerate wake vortex decay by optimal perturbations enhancing inherent instability mechanisms. The flow field has been investigated for a half plane of the entire wake up to a distance of 48 span dimensions downstream of the model. The results obtained at 1, 12, 24 and 48 span distances are shown as non-dimensional axial vorticity and vertical turbulence intensities. A significant decay in peak vorticity, swirl velocity and circulation is observable during the downward motion of the vortices. Spectral analysis of the unsteady velocity data reveals a peak in the power spectral density distributions indicating the presence of a dominating instability. Using two hot-wire probes cross spectral density distributions have also been evaluated, which highlight the co-operative instability leading to a rapid wake vortex decay within 30 span dimensions downstream.

Original languageEnglish
Pages (from-to)114-129
Number of pages16
JournalAerospace Science and Technology
Issue number2-3
StatePublished - Mar 2009


  • Correlation
  • Decay
  • Experiment
  • Instabilities
  • Wake vortices


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