Enhancement of synthetic jets by means of an integrated valve-less pump

2015

EPJ Web of Conferences

Self Cite

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.

Section: Resultsmentioning

confidence: 99%

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

Broučková

Vít

2015

EPJ Web of Conferences

Self Cite

“…Following the previous experience with SJ actuators (Trávníček et al [8][9][10][11][12]), the full scale axial fan was equipped by electrodynamically driven SJ actuators, located at the IGVs. Namely three SJ actuators were built in the fan casing near the IGVs at the expected separation points.…”

Section: Synthetic Jet Actuators and Experimental Methodsmentioning

confidence: 99%

“…Figure 3 shows that the maxima of the velocity are found at 600 Hz for both variants, which are approximately 32 m/s and 38 m/s, respectively. These maxima are relevant to the first resonance of the actuator resulting from the mechanical energy transformation -namely the kinetic energy of the fluid column and the potential energy of the diaphragm are mutually transformed [8]. Finally, the frequency (600 -700) Hz was chosen as the operating frequency range.…”

Section: Efm 2012mentioning

confidence: 99%

Flow control in axial fan inlet guide vanes by synthetic jets

Cyrus

Wurst

et al. 2013

EPJ Web of Conferences

Abstract. Tested high pressure axial flow fan with hub/tip ratio of 0.70 and external diameter of 600 mm consisted of inlet guide vanes (IGV), rotor and stator blade rows. Fan peripheral velocity was 47 m/s. Air volume flow rate was changed by turning of rear part of the inlet guide vanes. At turning of 20 deg the flow was separated on the IGV profiles. The synthetic jets were introduced through radial holes in machine casing in the location before flow separation origin. Synthetic jet actuator was designed with the use of a speaker by UT AVCR. Its membrane had diameter of 63 mm. Excitation frequency was chosen in the range of 500 Hz -700 Hz. Synthetic jets favourably influenced separated flow on the vane profiles in the distance of (5 -12) mm from the casing surface. The reduction of flow separation area caused in the region near the casing the decrease of the profile loss coefficient approximately by 20%.

“…This method has been also applied to SJ actuator design: two actuator cavities separated by a common diaphragm, so that they operate in the antiphase -see, e.g., Lee and Goldstein (2002), TrávníĀek et al(2004, 2005aand 2005b, and more recently Luo et al (2006).…”

Section: Regular Papermentioning

confidence: 99%

“…The "hybrid synthetic jet" (HSJ) combines the ZNMF jet and a fluidic pumping by a valve-less pump -as described in previous publications by TrávníĀek et al (2005aTrávníĀek et al ( , 2005bTrávníĀek et al ( and 2006, and Chen et al (2006). In contrast to the standard SJ, the HSJ is an intrinsically non-zero-net-mass-flux jet.…”

Section: Introductionmentioning

confidence: 99%

Performance of synthetic jet actuators based on hybrid and double-acting principles

Tesař

Kordík

2008

J Vis

The design of the discussed fluid jet actuator followed two ideas: a double-acting operation of reciprocating pumps, and a hybrid synthetic jet (HSJ) actuation. The entire actuator consists of two basic parts, namely the front (central) and rear chambers, from which fluid is displaced by the opposite sides of the same diaphragm. The actuator operates in a double-acting (antiphase) regime with air as the working fluid. The central chamber generates the standard (zero-net-mass-flux) axisymmetric synthetic jet (SJ), while the rear chamber generates system of several non-zero-net-mass-flux HSJs arranged around the central SJ. A number of variants of HSJs with different geometry were designed, manufactured and tested. Their behavior was investigated experimentally using the smoke visualization, reaction force measurement, hot-wire anemometry, and naphthalene sublimation technique. The tests confirm the efficiency of the present design.