An experimental investigation is carried out to study the unsteady near wake behind an oscillating airfoil. The airfoil is given the harmonic pitching motion about the one-quarter chord axis. The reduced frequency is varied from 0.1 to 0.3. The mean incidence angle and the amplitude of oscillation are 0° and 7.4°, respectively. Streamwise velocity and the Reynolds stress profiles are measured by hot-wire anemometry. The unsteady wake of the present work undergoes various states of change. The measurement data are presented in conjunction with the various flow states of the pitching airfoil. Effect of the reduced frequency on the wake properties are discussed.
