The control the tip vortex flow characteristics in the near field behind an oscillating NACA 0015 airfoil at Reynolds numbers Re = 1.65 x 105 by means of a full-span trailing-edge flap (TEF) flow-control actuator was tested in a wind tunnel. The oscillating wing was chosen to simulate the quasiperiodic first harmonic angle of attack variations that are found on helicopter rotors during lowspeed forward flight. The instantaneous velocities of the tip vortex were measured by a miniature triple hot-wire probe and were subsequently ensemble averaged over 40-80 oscillating cycles to obtain phased-locked averages of the flow properties at various phase positions during the cycle. Both positive and negative flap deflections, actuated at different start times, were tested. The negative flap motion was found to be most effective in displacing the vortex position with earlier actuations leading to larger vertical vortex displacements. Negative flap deflections strengthened the vortex, moved the centroid further outboard, decreased the peak vorticity and increased the vortex size. The positive trailing-edge flap motion, however, resulted in a more concentrated tip vortex of reduced vortex strength located further inboard. The lift-induced drag was decreased (increased) for positive (negative) trailing-edge flap, compared to a baseline wing.
Active trailing-edge flap control of oscillating-wing tip vortex
Aktive Kontrolle des Spitzenwirbels an einem schwingenden Tragflügel durch Verstellung einer Klappe
AIAA Journal (online) ; 44 , 11 ; 2746-2754
2006
9 Seiten, 7 Bilder, 1 Tabelle, 24 Quellen
Article (Journal)
English