Experimental techniques applied to the study of wingtip vortices are of great interest for the
Fluid Mechanics Community. The available experimental techniques to obtain new insights into
trailing vortices, focus on quantitative methods, e.g. Particle Image Velocimetry (PIV)1,2. In fact,
this technique requires high costs associated not only to equipments but also to image
processing that is a complex, and time consuming task. A novel, easier, faster and cheaper
experimental procedure is presented in this research work to compute experimentally the
vortex structure in comparison to a theoretical model.
Different theoretical models have described the velocity field for every cross section along
the axial coordinate, once the vortex was created at the wing tip. These models depend on
several parameters and provide the axial evolution of the velocity field. We used in this study a
q-vortex or Batchelor’s3 model, based only on two free parameters: swirl value, q, and the
virtual origin in the axial coordinate, z0. These parameters have been processed with the
experimental trailing vortex formed by a NACA0012 aerofoil over a Reynolds number range of
105. The experimental setup consists of one smoke wire device together with a laser beam, and a
digital camera installed in a subsonic wind tunnel. A smoke segment was generated upstream
the model, but near the wing edge. This line followed the main stream passing through the wing
tip. Lift forces produced the characteristic vortex pattern, highlighted by the swirling smoke
segment, and whose topological structure was recorded by a digital camera. Several sections at
different axial distances from the wing edge have been analyzed. The integration of the velocity
field in the theoretical model allowed us to know two theoretical parameters in order to obtain
similar experimental streaklines at a given axial position, as shown in figure 1. The experimental
results using this procedure were in agreement with those found in the literature1.
Buscar en Dimension