Effect of an axial jet on vortex merging

David Marles, Ismet Gursul

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Experiments were conducted to understand the effect of an axial jet on the merging process of a simulated flap-edge and wing-tip corotating vortex pair in the near wake. Cross-flow velocity measurements and flow visualization were performed for the three realistic jet positions on both equal and unequal strength like-signed vortices for a range of momentum coefficients. The main finding was that the initial jet position has a vastly contrasting effect on the merging process. If the jet turbulence rapidly interacts with only one of the vortices, severe diffusion of that vortex occurs which ultimately wraps around and becomes consumed by the unaffected vortex structure. The jet causes a reduction in the vortex spacing and an increase in the rotation angle; hence, merging is promoted. If the jet turbulence does not directly interact with either vortex but instead interferes with the mechanism in the outer-recirculation region that advects vorticity to a larger radius, then merging can be retarded. In this case, an increase in vortex spacing and reduction in rotation angle were observed. Increasing the momentum coefficient, hence, introducing more turbulence into the flow, has a greater effect on the merging process. © 2008 American Institute of Physics.
Original languageEnglish
Article number047101
Number of pages16
JournalPhysics of Fluids
Issue number4
Early online date20 Apr 2008
Publication statusPublished - Apr 2008


  • Wakes
  • Turbulent flow
  • Flow velocity
  • Jets
  • Vortex flow
  • Flow simulation
  • Flow visualization


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