Evolution of a Synthetic Jet with Triangular Orifice Geometry at Varying Skew Angles in a Laminar Boundary Layer

Synthetic jets have been widely investigated as an actuator for active flow control. The present experimental study investigates the interaction of a finite aspect ratio synthetic jet actuator having a triangular orifice geometry with a laminar boundary layer over a flat plate, and the effect of the skew angle of the orifice on this interaction. The skew angles studied are 0°, 45°, 90°, 135°, and 180°, with 0° corresponding to the jet orifice oriented parallel to the flow with the tip of the triangle pointing downstream. The study was conducted using Stereoscopic Particle Image Velocimetry (SPIV). Results show that the near field is highly unsteady at all orientations. Moreover, the triangular orifice produces a pair of counter-rotating vortices with the far-field characteristics varying significantly with skew angle. While at a skew angle of 0° a pair of symmetric vortices are present, only a single dominant vortex is present at 45° skew. The vortices produced are also found to be stronger and extend farther downstream when the orientation is such that the base of the triangle is upstream of the tip. The variation in the number and strength of the vortices with skew could prove a synthetic jet with a triangular orifice to be a versatile actuator.