Study of a Synthetic Jet as a Building Block for Turbulence Facilities

Our work studies the development of multi-orifice synthetic jets (SJs). We show that scaling arguments for our multi-orifice jet are consistent with the development of a single-orifice SJ. In the context of using these SJs as actuators in a turbulence box, we focus on optimizing the turbulent kinetic energy (TKE). TKE is not typically investigated, with most literature focusing on velocity profiles and development. Our hexagonally packed orifice geometry minimizes axis switching and develops into a merged axisymmetric jet. Because multiple orifices lead to more TKE-producing shear layer structures, our latest iteration of testing focuses on an increasing number of orifices. The maximum number of orifices that fit within the loud speaker diaphragm decreases with increasing orifice diameter, but a balance may be struck between number and size of the created shear layers. Additionally we use a pressure probe to track the usage of the jet reservoir. With increasing total orifice area we expect that the diaphragm will need to deflect more to compensate for a faster loss in pressure. The geometries and operating conditions for our SJ must thus be tuned to ensure an optimal level of turbulence is achieved in a facility which uses such SJs as building blocks for creating turbulence.