Vortex formation of a finite span synthetic jet

The effects of different geometries and input parameters on the flow structures of a finite span synthetic jet are explored in quiescent flow experiments using stereoscopic PIV. Common geometrical parameters, such as neck height, and orifice aspect ratio are varied along with the jet performance characteristics such as Strouhal numbers and Reynolds numbers. Orifice neck heights of 2, 4 and 6mm were tested at aspect ratios of 6, 12, and 18. Jet Strouhal numbers of 0.115 to 0.157 were tested at Reynolds numbers of 615. It is found that as the aspect ratio was increased the size of the vortical structures decreases, the vorticity dissipation rate increases, and axis switching occurred farther away from the orifice. The neck length had a large effect on the structures' size and strength, their dissipation rate, and the jet's spreading. Moreover, the driving frequency was found to affect the vortical structures spreading due to the streamwise spacing between structures, as well as drastically affecting dissipation of the structures in both planes.