Optimization of a piezoelectric acoustical compressor

Abstract

A one-dimensional, axisymmetric, linear finite element model describing a fluid interacting with a piezoelectric actuator is developed. This system is used to generate finite amplitude standing waves in an acoustic cavity with rigid walls. The model includes the effects of viscous and thermal damping of the fluid at the boundary of the cavity, and material damping in the piezoelectric actuator. Two types of piezoelectric actuators are considered, a stacked layer actuator, and a bending bimorph actuator. The resulting finite element equations are used to determine the optimum shape for the acoustic cavity that results in the highest pressure for the least input power. Optimal chambers were found that could generate ± 19 psi at 1700 Hz for 50 watts of power using air as a working fluid and ± 70 psi at 950 Hz for 42 watts of power using R-134A as a working fluid. The optimization results were verified against the commercial finite element code ANSYS and published experimental data.