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Effect of tracer particle characteristics on visualisation of delta wing vortices

Published online by Cambridge University Press:  04 July 2016

D. I. Greenwell*
Affiliation:
QinetiQ Bedfordshire, UK

Abstract

Preliminary investigations of the effect of tracer particle characteristics on flow visualisation in a steady delta wing leading-edge vortex are presented, using both 3D simulations of particle trajectories and a simplified analysis of the radial equilibrium conditions. It is shown that many of the flow structures apparently seen in wind and water tunnel visualisation studies of delta wing vortices may in fact be artefacts of the tracer particle characteristics. In particular the ‘smoke tube’ or ‘hole’ effect often seen in smoke flow visualisation in wind tunnels does not (contrary to popular usage) indicate the size of the viscous subcore, and is not a reliable indicator of the vortex structure. The implications for both visualisation studies and optical flow measurement techniques are discussed.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 2002 

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