Parametric Investigation of Sweeping Jet Actuation for Near-Wall Flow Recovery in a Curved Channel

This study presents a planar particle image velocimetry (PIV) investigation of near-wall velocity deficit mitigation in a compact curved channel using sweeping jet actuation. A compact sweeping jet oscillator was developed based on a simplified fluidic oscillator configuration and integrated into the curved wall region of the channel. The effects of jet incidence angle, actuator placement, array layout, and jet-to-freestream velocity ratio were examined within a fixed streamwise measurement window near the curved wall. The analysis focuses on time-averaged in-plane velocity fields and representative streamwise velocity profiles, with emphasis on changes in the near-wall low-speed region and local streamwise velocity recovery. The results show that sweeping jet actuation can weaken the measured near-wall low-speed region and promote local streamwise velocity recovery within the planar PIV window. Among the tested cases, a jet incidence angle of 60° and actuator placement at the beginning of the bend produced a more balanced local recovery response. The comparison between different array layouts indicates that the observed recovery is affected by the combined influence of actuator spacing, actuator number, and total actuation input; therefore, it should not be interpreted as an isolated spacing effect. The present results provide a systematic low-speed experimental basis for selecting sweeping jet incidence angle, actuator placement, array configuration, and equivalent actuation input in compact curved channel flow control applications. The findings clarify how different actuation parameters affect local near-wall velocity deficit mitigation and streamwise velocity recovery within a controlled optical access configuration.