Development of piezoelectric-based membranes for synthetic jet actuators: experiments and modeling

A mathematical model was developed to represent the behavior of circular piezoelectric bimorphs in a synthetic jet actuator. Synthetic jet actuators are popular active flow control devices whose application is being widely explored in aerodynamics. The material properties were matched to those of PZT-5A mounted on a substrate. The actuator's geometry consisted of a cylindrical cavity of low height to diameter aspect ratio. A bimorph formed one of the cylinder's bases. The ingestion/expulsion orifice for the synthetic jet actuator was placed in the edge of the cavity so as to allow for either the present single bimorph or future dual bimorph configurations. Simply supported and rigidly supported boundary conditions were assessed around the circumference of the bimorph. The potential of alternate mode shapes occurring in the bimorphs during operation of the synthetic jet was evaluated. A limited parametric study was conducted varying the thickness of the piezoelectric wafers used in the bimorphs and the geometry of the cavity and orifice. Results were obtained for the displacement of the center of the bimorph's surface and the peak velocity of the air being ingested and expulsed through the orifice. These results were compared to values obtained through a mathematical model. Experimental data present in literature were also compared. The mathematical model was seen to have considerable potential for predicting the performance of synthetic jet actuators and their resonant frequencies but failed to capture the effects of acoustic coupling with the cavity, which is a topic of future research.