Comparison of synthetic jet actuators based on sharp-edged and round-edged nozzles

Abstract

Abstract. Axisymmetric synthetic jet actuators based on a loudspeaker and on two types of flanged nozzles were tested and compared experimentally. The first type of the nozzle was a sharp-edged circular hole. The second one had a special design with fillets at inner and outer nozzle exit and with a small step in the middle of the nozzle. The function of the step was to prevent the flow reattachment during the extrusion stroke. The actuators with the two types of nozzles were operated at resonance and were compared first qualitatively using a simple phase locked flow visualization. Then the hot-wire anemometer was used to measure velocity distributions along nozzle axis and velocity profiles at the nozzle exit. Comparison of the nozzles was based on evaluation of the characteristic velocity and integral quantities (volumetric, momentum, and kinetic energy fluxes). It was found out that these quantities, which were evaluated at the nozzle exit, differ substantially for both nozzles. On the other hand the velocity flow field in farther distances from the nozzle exit area did not exhibit such prominent differences.

Synthetic jet actuator with two opposite diaphragms

“…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].…”

“…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]. The results were even higher (43.3% for momentum flux and 70.8% for kinetic energy flux) for other measured parameters.…”