Synthetic jet actuators (SJA) are zero net mass flux (ZNMF) devices traditionally constructed by forming a cylindrical cavity with an orifice in either its side or one of its bases (See Figure 1). Piezoelectric disks are used as either one (a) or both (b) of the bases. The disks are then vibrated by means of AC voltages. As the disks move inward and outward, the volume of the cavity changes and air is rapidly ingested and ejected through the orifice. The train of vortices produced outside orifice by this process coalesces into a jet which imparts momentum to the flow field even while the ingestion of air into the actuator maintains the mass transfer of the system at zero. SJAs have potential as active flow control devices for application on trucks, planes, and buildings. The major advantage of SJAs over conventional jets is that they are self-contained, electrically powered devices and do not require a source of compressed air.
This project sees to increase both the velocity and momentum that SJAs are able to produce by means of better understanding the internal and external flow fields and improving the SJA's design accordingly. The parameters being modified include the cavity and orifice geometries, the boundary conditions of the vibrating peizoelectric disks, and the construction of the piezoelectric disks themselves. Experimental data is being collected on a variety of actuator sizes and configurations. These include jet velocity (by means of hot wire anemometry), disk displacement maps, internal pressure distributions, power consumption, and flow field measurements (by means of particle image velocimetry, PIV). These will be compared to a theoretical model of the disks' interaction with the flow field.