Influence of unsteady wake on a turbulent separation bubble

Abstract

An experimental study was made of turbulent separated and reattaching flow over a blunt body, where unsteady wake was generated by a spoked-wheel type of wake generator with cylindrical rods. The influence of unsteady wake was scrutinized by altering the rotation direction (clockwise and counter-clockwise) and the normalized passing frequency (0 less than or equal to St(H) less than or equal to 0.20). The Reynolds number based on the cylindrical rod was Re-d = 375. A phase-averaging technique was employed to characterize the unsteady wake. The effect of different rotation directions, which gave a significant reduction of x(R), was examined in detail. The wall pressure fluctuations on the blunt body were analyzed in terms of the spectrum and the coherence.