VORTICES ISSUED FROM THE ROTOR BLADE TIPS OF A HELICOPTER IN FORWARD FLIGHT
Colored emissions at the blade tips show the cycloidal shape of the vortices as well as their lengthwise distribution. In
this example of unsteady three-dimensional flow, the knowledge of vortex paths and of their evolution as a function of various
parameters (rotor tilt angle, number of blades, etc.) sheds some liqht on the unwanted interaction effects of the vortices on
the following blades.
Image created by Henri Werlé. Reproduced with permission from his spectacular
collection Courants et Couleurs published in 1974 by ONERA, the French Aerospace Lab.
For further information, see
On the Flow of Fluids Made Visible,
Leonardo, Vol. 8, No. 4. (Autumn, 1975), pp. 329-331.