Helical-perturbation device for cylinder-wing vortex generators
A new device has been developed for introducing helical perturbations by means of low-level fluid injection into the cylinder boundary layer of a flow-aligned cylinder-wing vortex generator. Its basic characteristics have been analyzed and experimentally evaluated at moderate Reynolds numbers. When the cylinder boundary layer is tripped and there is no strong swirl, then in the near wake, the device lowers the mean rate of drop of the Strouhal number with Reynolds number by one-half