Vectoring and small-scale motions effected in free shear flows using synthetic jet actuators

Abstract

Novel fluidic actuators based on synthetic jet technology are used to effect thrust vectoring and manipulate small-scale motions in conventional air jets. Synthetic jets operate without net mass injection (and thus are comprised entirely of entrained fluid), have finite streamwise momentum, and are synthesized by the time-harmonic formation of a train of two-dimensional vortices at the edge of a sharp orifice. In the present experiments, millimeter-scale high aspect ratio actuator jets are placed along the long sides and near the exit plane of a primary rectangular jet scaling one to two orders of magnitude larger. The primary jet can be vectored either towards or away from the actuator jets at angles exceeding 30 deg (and 80 deg when pairs of actuator jets are operated in concert). The actuation frequency is at least an order of magnitude higher than the unstable frequency of the primary jet and thus results in direct excitation of small scale motions and enhanced turbulent dissipation. (Author)