Near wake vortex shedding and noise control using sweeping jet actuators

An experimental study was carried out to investigate the effectiveness of using sweeping jet actuators to suppress the vortex shedding associated with blunt trailing edges. Several configurations implementing sweeping jet actuators were considered for this study and were compared against the use of equivalent steady jets, through aerodynamic force measurements, time-averaged Particle Image Velocimetry (PIV) and hotwire anemometry measurements. The comparison of the fluctuating components of the measured aerodynamic forces, have demonstrated the advantageous reduction in the unsteady forces associated with using sweeping jet actuators over the use of steady blowing jets. PIV data captured at different spanwise locations relative to the jet outlet, showed that sweeping jets managed to suppress a significant scale of the vortex formation. On the other hand, the steady jets did not seem to fully suppress the main vorticities in a similar manner, breaking them into a set of smaller vortices instead. This agrees with spectral results obtained from hotwire velocity measurements, showing higher tonal reductions in the near wake region for the sweeping jet configurations. The study suggests the favourability of using sweeping jets for vortex suppression, provided that the scale of the sweeping component of the jets is accessing the core of the vortex.