Control of Helicopter Rotor Tip Vortex Structure using Blowing Devices

Numerical simulations are performed on a single bladed hovering rotor using the compressible Reynolds averaged Navier Stokes equations. An overset mesh system is used to accurately resolve the flow in the tip vortex region. The results from the simulations are compared with existing experimental data for the same configuration. The effect of steady spanwise and streamwise blowing on the structure of the tip vortex is studied. Both methods significantly diminished the swirl velocities and increased the core radius of the tip vortex, with only a marginal reduction in rotor thrust. The mechanisms causing the accelerated diffusion of vorticity are investigated. The overall numerical results suggest that these concepts hold promise in reducing the strength of rotor tip vortices.