Hybrid Lumped-Element and Finite Element Model for Novel Synthetic Jet Actuator Shapes

Abstract

A modeling approach was developed that combines lumped-element and finite element methods for analysis of synthetic jet actuator (SJA) geometries that deviate significantly from an ideal Helmholtz resonator. The diaphragm was modeled using the finite element method (FEM) coupled to lumped-element equations that govern the fluid flow. The loss coefficient was estimated based on the geometry of the cavity and orifice. A pressure acoustic FEM model of the cavity and orifice was used to determine a characteristic resonance frequency to use in place of the Helmholtz resonance frequency that appeared in the lumped element equations. The results were validated using experimental data for SJAs with geometries that deviate significantly from the Helmholtz resonator idealization. The combination of replacing the Helmholtz frequency with a more accurate characteristic frequency and using a computed value for the loss coefficient was shown to provide more accurate performance predictions for low-profile SJA designs.