Novel methods for evaluation of the Reynolds number of synthetic jets

Kordík, Jozef; Broučková, Zuzana; Vít, Tomáš; Pavelka, Miroslav; Trávníček, Z.

doi:10.1007/s00348-014-1757-x

Cited by 12 publications

(10 citation statements)

References 54 publications

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“…However, a usable application of LEM frequently needs additional measurements such as cavity pressure cyclesPersoons and O'Donovan [51]. To overcome this disadvantage, another method of SJ velocity evaluation has recently been proposed by Kordík et al [52]. This method is based on simple measurements of the actuator electrical inputs (alternating current and voltage).…”

Section: Introductionmentioning

confidence: 99%

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Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

Broučková

Vít

Trávníček

2015

EPJ Web of Conferences

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Abstract. The present study deals with a slot synthetic jet (SJ) issuing from an actuator into quiescent surroundings and driven by a piezoceramic transducer. The actuator slot width was 0.36 mm, with a drive frequency proposed near the theoretical natural frequency of the actuator. The working fluid was water at room temperature. The present experiments used flow visualization (a laser-induced fluorescence technique) and laser Doppler vibrometry methods. Flow visualization was used to identify SJ formation, to demonstrate its function, and to estimate SJ velocity. Laser Doppler vibrometry was used to quantify diaphragm displacement and refine operating parameters. Phase averaging yielded a spatial and temporal diaphragm deflection during the actuation period. Taking incompressibility and continuity into consideration, the velocity in the actuator slot and the Reynolds number of the SJ were evaluated as 0.21 m/s and 157, respectively. The present results confirmed a SJ actuator function at the resonance frequency of approximately 46 Hz, which corresponds closely with the theoretical evaluation. The laser Doppler vibrometry results corresponded closely with an estimation of SJ velocity by the present flow visualization.

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Section: Introductionmentioning

confidence: 99%

“…This method is based on simple measurements of the actuator electrical inputs (alternating current and voltage). However, none of the models is a self-salvable key, and the method [52] is only valid for well-defined loudspeaker-based actuators using air as the working fluid.…”

Section: Introductionmentioning

confidence: 99%

Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

Broučková

Vít

Trávníček

2015

EPJ Web of Conferences

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“…, (8) where is the counter-electromotive force, which contributes to the voltage drop across the loudspeaker clamps; for details, see [16], [22], [58];…”

Section: Appendix a -Derivation Of Functions Andmentioning

confidence: 99%

“…The actuators of SJs use moving pistons (see [3]- [9]), piezoceramic composite diaphragms (see [10]- [15]), or electro-dynamically driven diaphragms (see [16]- [22]) for generation of the pulsations. The diaphragm or piston usually creates one side of a closed cavity that is connected with the ambiance by a nozzle.…”

Section: Introductionmentioning

confidence: 99%

Energetic efficiencies of synthetic and hybrid synthetic jet actuators driven by electrodynamic transducers

Kordík

Trávníček

Pavelka

2015

Experimental Thermal and Fluid Science

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“…Therefore, many authors concentrated their efforts on location and prediction of the SJ actuator resonances (see e.g. [32][33][34][35][36][37][38][39][40][41][42][43][44]). Having a SJ actuator operating at a resonance frequency, there still exist other ways how to enhance its exploitable outlet quantities such as volumetric flux, momentum or kinetic energy fluxes.…”

Section: Introductionmentioning

confidence: 99%

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

Kordík

Trávníček

2017

EPJ Web Conf.

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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.

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Novel methods for evaluation of the Reynolds number of synthetic jets

Cited by 12 publications

References 54 publications

Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

Energetic efficiencies of synthetic and hybrid synthetic jet actuators driven by electrodynamic transducers

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

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