Acoustic and Flow Aspects of Synthetic Jet Actuators with Chevron Orifices

Smyk, Emil; Markowicz, Marek

doi:10.3390/app11020652

Cited by 12 publications

(18 citation statements)

References 37 publications

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“…The loudspeaker STH M. 18.200.8.MCX was used. The same actuator but with other orifices was used in [29].…”

Section: Methodsmentioning

confidence: 99%

“…It made that the vortex ring is not circular but more complex, but dissipate faster than vortices in the case of the circular nozzle. Smyk and Markowicz [29] showed that the time-average centerline velocity is the same for chevron and circular SJ in a distance x/d = 6, where x is an axial distance from the orifice and d is an orifice diameter. During, the centerline momentum velocity was the same, regardless of the type of orifice.…”

Section: Introductionmentioning

confidence: 99%

“…Smyk and Markowicz [29] investigated the SPL of SJA with a chevron orifice. The orifice had the same number of chevrons but differed in the height of cutouts.…”

Section: Introductionmentioning

confidence: 99%

“…In the paper [29], it was noticed that the sharp edge in the bottom of the chevron orifice can cause an increase in the SPL. So, if it is true, the rounding of this orifice can decrease the SPL generated by SJA.…”

Section: Introductionmentioning

confidence: 99%

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Sharp and Rounded Cutouts in a Chevron Orifice and Them Impact on the Acoustic and Flow Parameters of Synthetic Jet

Smyk

2021

Applied Sciences

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The application of a synthetic jet actuator in workplaces entails the necessity of noise reduction, which they generate. One of the methods to achieve this is the use of the chevron orifice or nozzle. Therefore, the impact of different numbers of chevrons and rounding of cutouts in the orifice on the actuator efficiency and the sound pressure level was tested. The chevron orifices were compared to the circular orifice. The time-mean reaction force method was used to measured efficiency and flow parameters, and the noise was measured according to the ISO 3746:2010. The rounded cutouts had an advantageous impact on the actuator efficiency at the power P >1 W, while the efficiency of the actuator with classic chevron orifice was smaller than with circular orifice. The noise generated by the actuator with the chevron orifice was smaller from 0.6 to 1.6 dB than by the actuator with the circular orifice, at the number of chevrons equal to 7 or more. The rounding of cutouts in the chevron orifice can advantageously impact the parameters of synthetic jet actuators.

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“…The loudspeaker STH M. 18.200.8.MCX was used. The same actuator but with other orifices was used in [29].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Smyk and Markowicz [29] investigated the SPL of SJA with a chevron orifice. The orifice had the same number of chevrons but differed in the height of cutouts.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sharp and Rounded Cutouts in a Chevron Orifice and Them Impact on the Acoustic and Flow Parameters of Synthetic Jet

Smyk

2021

Applied Sciences

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“…There are many studies and research projects treating the jet noise reduction [5,6], but the simplest technique is to manufacture chevrons on the nozzle without having high loss of the propulsion force [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Impact of Using Chevrons Nozzle on the Acoustics and Performances of a Micro Turbojet Engine

Cican

Deaconu

2021

Applied Sciences

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This paper presents a study regarding the noise reduction of the turbojet engine, in particular the jet noise of a micro turbojet engine. The results of the measurement campaign are presented followed by a performances analysis which is based on the measured data by the test bench. Within the tests, beside the baseline nozzle other two nozzles with chevrons were tested and evaluated. First type of nozzle is foreseen with eight triangular chevrons, the length of the chevrons being L = 10 percentages from the equivalent diameter and an immersion angle of I = 0 deg. For the second nozzle the length and the immersion angle were maintained, only the chevrons number were increased at 16. The micro turbojet engine has been tested at four different regimes of speed. The engine performances were monitored by measuring the fuel flow, the temperature in front of the turbine, the intake air flow, the compression ratio, the propulsion force and the temperature before the compressor. In addition, during the testing, the vibrations were measured on axial and radial direction which indicate a normal functioning of the engine during the chevron nozzles testing. Regarding the noise, it was concluded that at low regimes the noise doesn’t presents any reduction when using the chevron nozzles, while at high regimes an overall noise reduction of 2–3 dB(A) was achieved. Regarding the engine performances, a decrease in the temperature in front of the turbine, compression ratio and the intake air and fuel flow was achieved and also a drop of few percent of the propulsion force.

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