Maximization of integral outlet quantities of an axisymmetric synthetic jet actuator based on a loudspeaker

Abstract

The goal of this paper is to find an optimal nozzle size of an axisymmetric synthetic jet actuator based on a loudspeaker. The desirable maximized output quantities are: volumetric flow, momentum flux, and kinetic energy flux. To evaluate these quantities velocity profiles were measured using a hot-wire probe at the actuator nozzle exit. Six different nozzle diameters and three supplied real power levels were tested to find the maxima of the quantities. The actuator operated always at resonance during experiments. It was found out that the momentum flux and the kinetic energy flux reach distinguishable local maxima at particular diameters of the nozzle. Besides, the maxima of the particular quantities do not coincide and the best nozzle size slightly increases with the supplied real power to the actuator.

Synthetic jet actuator with two opposite diaphragms

“…where ωps is the frequency of pneumatic spring of the actuator cavity: (11) and ωn = 2πfn (12) CR represents the ratio of air stiffness (air in the cavity of volume Vc and cross-section area Sc) to membrane stiffness. If CR << 1, the membrane dynamics is uncoupled from the acoustic oscillator.…”

“…Due to many applications, SJs are produced with the use of many types of different actuators (in terms of construction and type) so as to increase the SJ efficiency or velocity. Kordík and Trávníček [10,11] studied the dependence between the integral quantities (volumetric flux, momentum flux and kinetic energy flux) of SJs and the nozzle geometry. They demonstrated that the use of a nozzle with rounded edges increases the SJ characteristic velocity even by 18.5%, as compared to the same SJA with a sharp-edged nozzle [10].…”