UNSTEADY PRESSURE MEASUREMENTS FOR PARALLEL VORTEX-AIRFOIL INTERACTION AT LOW-SPEED

Two-dimensional vortex-airfoil interaction at airfoil chord Reynolds n umber 6 x 10(4) is studied experimentally by immersing an instrumented NACA 0012 airfoil downstream of a vortex generator airfoil that pitch es in a tailored nonsinusoidal form, A clockwise rotating vortex is ge nerated to approach the target airfoil from left to right, When the vo rtex interacts with a nonlifting airfoil, it creates rather sharp and local variations of surface pressure in the vicinity of the leading ed ge, For airfoils at an angle of attack (alpha = 5 and 10 deg), the pre ssure variations appear to be spread over nearly the entire surface, N evertheless, a greater magnitude in the amplitude of transient Lift is noted on the airfoil at high angle of attack (alpha = 10 deg), primar ily because of a low-pressure plateau region formed on the upper surfa ce that occurs when the vortex moves downstream of the trailing edge, The amplitude of transient lift is also found to increase with a reduc tion in the vertical separation between the vortex generator and the a irfoil.