EFFECTS OF LEADING AND TRAILING-EDGE FLAPS ON THE AERODYNAMICS OF AIRFOIL VORTEX INTERACTIONS/

A numerical procedure has been developed for predicting the two-dimens ional parallel interaction between a free convecting vortex and a NACA 0012 airfoil having leading and trailing edge integral-type flaps. Sp ecial emphasis is placed on the unsteady flap motion effects which res ult in alleviating the interactions at subcritical and supercritical o nset flows. The numerical procedure described here is based on the imp licit finite-difference solutions to the unsteady two-dimensional full potential equation. Vortex-induced effects are computed using the Bio t-Savart Law with allowance for a finite core radius. The vortex induc ed velocities at the surface of the airfoil are incorporated into the potential flow model via the use of the velocity ''transpiration'' app roach. Flap motion effects are also modeled using the transpiration ap proach. For subcritical interactions, our results indicate that traili ng edge flaps can be used to alleviate the impulsive loads experienced by the airfoil. For supercritical interactions, our results demonstra te the necessity of using a leading edge flap, rather than a trailing edge flap, to alleviate the interaction. Results for various time-depe ndent flap motions and their effect on the predicted temporal sectiona l loads, differential pressures, and the free vortex trajectories are presented.