Comparative Study on Multi-Actuator Interaction of Different Fluidic Actuators Over a Flat Plate

An experimental investigation was conducted to characterize the interaction and the mixing of the jet emitted from various types of fluidic actuator arrays over a flat plate under incoming flow conditions. The experiments were conducted in the low-speed wind tunnel at the University of Alabama in Huntsville (UAH). Three different types of fluidic actuators (i.e., sweeping jet (SWJ) featuring unsteady high exhaust velocity and large influence area, diverging jet (DVJ) featuring intermediate influence area, and straight jet (STJ) featuring high exhaust velocity) were investigated in the present study. Five 3D-printed actuators were combined into an array configuration, with the exit nozzles positioned orthogonally into the incoming flow boundary layer. Under the same flow rate, various free stream velocities were selected to investigate the flow mixing behavior. During the experiment, both Planar and Stereo PIV setups are used to characterize the behavior of both individual actuator and the actuators in array configuration from streamwise and spanwise planes. The results show that the exhaust jet from the SWJ oscillates at a high frequency, while DVJ and STJ show relatively steady behavior. The oscillation motion of the SWJ induced a significantly stronger lateral velocity compared to the other two steady jet actuators. Such lateral velocity leads to a strong interaction between two adjacent actuators. The Planar PIV results along the freestream direction illustrate that STJ has a large vertical influence area, as all the momentum of the jet is concentrated in the vertical direction. The Stereo PIV investigation reveals that while the SWJ induces a complex flow mixing structure at the downstream positions, the STJ results in a stronger steady vortex along the freestream direction.