Active Control of a Synthetic Jet-Actuated Three-Dimensional Turbulent Wall Jet

An experimental study is presented on the active control of a three-dimensional turbulent wall jet at [Formula: see text] using eight synthetic jet actuators at the nozzle exit. The unforced three-dimensional wall jet exhibits a downstream lateral growth rate that is roughly 5.5 times greater than the vertical growth, making it appealing in applications such as film cooling and separation control. The unforced development is compared to the forced wall jet in the development region containing the onset of the large lateral spread. The exploration of each case consists of two-dimensional velocity field measurements in the plane parallel to the wall and offset from the wall by half of the nozzle diameter and unsteady wall pressure field measurements. Significant control authority over the lateral growth can be achieved with synthetic jet actuation at the nozzle, both with in-phase and out-of-phase actuation. Operating the actuators out-of-phase is especially significant where the lateral growth was measured to increase by 140% over the unforced wall jet. Additionally, this study finds that the standard deviation in the wall pressure fluctuations off the jet centerline is correlated with the lateral growth of the three-dimensional wall jet. These findings suggest that the three-dimensional turbulent wall jet is a promising feedback flow control case study, as the multipoint time-resolved wall pressure measurements may be practically implemented in closed-loop control approaches.