Design analysis of a piezoelectrically driven synthetic jet actuator

Abstract

Technological advancement is being realized by using piezoelectric synthetic jet actuatorsto generate managing forces and moments with zero-net-mass-flux oscillatory jets forvarious air flow control applications. This paper firstly explores the synthetic jet flowbehavior for a dual-diaphragm piezoelectrically driven synthetic jet actuator. In theexperimental study, a flow visualization system was utilized to acquire the particle streakimages scattered from red fluorescent spheres for examining the synthetic jet flow. Thecenterline velocity of the jet was measured with a hot-wire anemometer. For exploring theformation progression of synthetic jets, the numerical analysis implemented unsteadythree-dimensional conservation equations of mass and momentum with a standardk–ε two-equation turbulent model adopted for turbulence closure. The moving boundary wasalso treated to represent the motion of the piezo diaphragm under actuation.For a complete sinusoidal actuation cycle at an operating frequency of 648 Hz,the synthetic jet flow pattern was simulated and compared with the visualizedimage and measured centerline velocity distribution to validate the computersoftware. In general, the far-field flow structure was fairly similar to a commoncontinuous turbulent air jet; whereas, the predicted time-recurring formation ofa vortex pair was observed in the near field. The surrounding air close to theslot was also drawn into the cavity of the actuator when vortex pairs advectedsufficiently downstream. Numerical experiments were then extended to assess theperformance of synthetic jet actuators by systematically varying the driving voltage,relative phase delay of frequency, width of the slot and depth of the actuatorcavity.