Active flow control for NACA 6-series airfoil at Re = 64,200

Earlier research for the NACA 64₃-618 airfoil has shown that lift-curve and stall behavior change noticeably when the chord Reynolds number is reduced significantly below its design value. For the same airfoil and a Reynolds number based on chord of Re = 64,200, separation control by pulsed vortex generator jets and a two-dimensional volume forcing that was motivated by a plasma actuator were investigated. Pulsed vortex generator jets with moderate jet velocities and the two-dimensional volume forcing were found to introduce coherent spanwise structures that are highly effective for separation control. A linear stability analysis of the time-averaged flow showed that span wise disturbances are amplified by an instability mechanism, which explains why both control strategies are highly efficient Angled pulsed vortex generator jets with large jet velocities were found to introduce streamwise vortices and to result in earlier transition. Although the control is highly effective, it is not very efficient, as streamwise vortices are not supported by the flow.