Tip Vortices of Oscillating Wings

Time-dependent structure and circulation of tip vortices shed from oscillating wings may influence various aerodynamic aspects: induced drag, gust response, aircraft wake hazard, formation flight, helicopter blades in forward flight, etc. As the wing pitches or plunges both the trajectory and strength of vortices are expected to vary. Water tunnel and wind tunnel experiments will be conducted for oscillating wings to investigate these aspects. Flow visualization, force measurements, Particle Image Velocimetry measurements will be performed. Vortex trajectories will be studied for different wing oscillation frequencies. Quantitative measurements of the velocity field will allow the analysis of the most energetic unsteady modes and instabilities by means of Proper Orthogonal Decomposition method. Active and passive flow control methods will be investigated to explore how the unsteady tip vortices can be controlled for specific purposes.