Development of a Trailing Vortex Formed With Spanwise Tip Blowing Available to Purchase

Trailing vortices were formed with strong core jets and high turbulence levels in a wind tunnel using a NACA 0015 rectangular semi-span wing having a full span aspect ratio of 5 and a chord Reynolds number of 10⁵. The jet on the vortex core was generated by air blown from the wing tip through small holes arranged along the periphery of the wing cross-section. Experiments covered a wide range of tip jet blowing rates for a wing incidence of 5°. Measurements of mean velocity, mean vorticity and turbulence kinetic energy were made up to 32 chords downwind using a hot wire probe. At zero wing incidence the flow was observed to have the form of a jet in cross-flow with counter-rotating streamwise vortices of zero net circulation and a very high turbulence level. With the wing at incidence, the tip vortex envelopes the jet and as it develops its diameter grows and the jet velocity and circumferential velocity decline sharply. Further downwind the vortex formed with tip jets evolves into an axisymmetric form similar to a natural vortex but with a diameter up to 5 times larger. The turbulence intensities measured on the core without blowing were ∼2.5% of the free stream velocity while with blowing they were ∼15% in the near wake and ∼9% in the far wake.