Finite element analysis and performance evaluation of synthetic jet actuators

Abstract

The primary objective of active flow control research is to develop a cost-effective technology that has the potential for revolutionary advances in aerodynamic performance and maneuvering compared to conventional approaches. The development of such systems have many implications for aerospace vehicles including: reducing mechanical complexity and hydraulic failure, reducing noise and weight, lowering energy and fuel consumption, lowering downtime and maintenance, enhancing maneuvering and agility with enhanced aerodynamic performance and safety. Interest in active flow control for aerospace applications has stimulated the recent development of innovative actuator designs that create localized disturbances in a flowfield. A novel class of devices, known as synthetic jet actuator, has been demonstrated to exhibit promising flow control capabilities including separation control and thrust vectoring. The basic components of a synthetic jet actuator are made of cavity and oscillating materials. The synthetic jet actuator developed at NASA LaRC has a small housing in which a cylindrical cavity is enclosed by two metal diaphragms, 50 mm in diameter, placed opposite each other. A circular piezoelectric wafer is attached to the center of the outside face of each metal diaphragm. The pair of piezoelectric metal diaphragms is operated with a 180° phase differential at the same sinusoidal voltage and frequency. With actuation, a synthetic jet issues from a 35.5mm long by 0.5mrn wide slot on the top of the device. In this study, a finite element model of synthetic jet actuator developed at NASA LaRC is investigated. The developed finite element model can be utilized to design and determine the performance of synthetic jet actuator. The analysis includes the FE model of circular plate, FE model of piezoelectric actuator/circular plate, piezoelectric (electrical field) /circular plate (structural field)/cavity (flow field) coupled system and experimental validation. The phase-average jet center velocity and amplitude of input voltage of piezoelectric actuator are predicted by this finite element model. The theoretical prediction is validated experimentally in this study.