On the flow physics and vortex behavior of rectangular orifice synthetic jets

Kumar, Abhay; Saha, A.; Panigrahi, Pradipta Kumar; Karn, Ashish

doi:10.1016/j.expthermflusci.2019.01.020

Cited by 19 publications

(7 citation statements)

References 18 publications

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“…The rectangular vortex ring shows broadly two types of vortex deformations: one that leads to axial switching of vortex ring and the other that causes bifurcation or splitting of vortex ring. The axial switching is common in rectangular vortex rings, as reported by many researchers in the past (Heertch 1976;Krothapalli et al 1981;Zaman 1996;Watson et al 2003 ;Kumar, et al 2019). It has been reported as the primary mechanism underlying the enhanced entrainment properties of non-circular jets relative to those of comparable circular jets.…”

Section: Introductionmentioning

confidence: 83%

“…Figure 1b shows the dimensions of the cavity and the diaphragm. It should be noted that the dimensions of the cavity, diaphragm, the water tank and the positioning of the orifice has been kept identical to the previously reported study (Kumar et al 2019). The actuator lies at a distance of 250 mm from the bottom of the tank as well as from the free surface, and the orifice of hydraulic diamter 12 mm (hydraulic diameter) yields a low blockage ratio of 2.4 %.…”

Section: Introductionmentioning

confidence: 95%

“…Therefore, the factors controlling the bifurcation process may behave differently in case of a synthetic jet. In an earlier work, we had investigated the flow physics and vortex behavior of rectangular orifice synthetic jets through LIF and Hot wire measurements and reported the occurrence of vortex bifurcation (Kumar et al 2019), although no clear understanding was gaiend as to what causes such bifurcation of rectangular orifice synthetic jets. Since the detailed mechanism of vortex bifurcation was not understood or discussed, a new series of experiments investigating the mechanism of vortex bifurcation was left as a future work.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The mechanism of vortex bifurcation vis-à-vis axial switching in rectangular synthetic jets

Kumar

Saha

Panigrahi

et al. 2021

European Journal of Mechanics - B/Fluids

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The mechanism of vortex bifurcation vis-à-vis axial switching in rectangular synthetic jets

Kumar

Saha

Panigrahi

et al. 2021

European Journal of Mechanics - B/Fluids

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“…This parameter is used as a formation criterion of SJ. It must be noted, that in this case the equivalent diameter was used [40], the hydraulic diameter [41], or another parameter e.g., slot width [5,42]. The formation criterion was fulfilled in the whole measuring range.…”

Section: Time-mean Reaction Force Measurementsmentioning

confidence: 99%

Synthetic Jet Actuators with the Same Cross-Sectional Area Orifices-Flow and Acoustic Aspects

2021

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In this paper, synthetic jet actuators (SJAs) with three different orifice shapes (circular, square, and slot) with the same cross-section area were investigated. The SJA efficiency and the synthetic jet (SJ) Reynolds number were calculated based on the time-mean reaction force measurement. The momentum velocity was measured with hot-wire anemometry and additionally, the sound pressure level (SPL) was measured. The efficiency was equal maximally to 5.3% for each orifice shape, but the square orifice characterized the higher Reynolds number. The compared centerline (axial) velocities and the radial velocity profile at a distance of 112 mm were similar for each orifice type. The SPL measurement results were surprisingly constant in relation to each other. The square orifice generates the lowest SPL, approximately 2.8dB lower than the circular orifice, and approximately 4.2dB lower than the slot orifice, at each investigated real power. Finally, the differences to other papers and limitations of the approach to comparing orifices presented in the present paper were indicated.

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“…This absence of net mass flux obviates the need for any additional pumping fluid, pump, moving components such as valves, piston etc. In addition, experiments carried out on synthetic jets have demonstrated that the vortex pairs predominate in the vicinity of the synthetic jet (Kumar et al 2019). These vortex pairs entrain more fluid from surroundings and along with a larger volume flux, a synthetic jet also widens more swiftly in comparison to a continuous jet (Swift, 2003).…”

Section: Introductionmentioning

confidence: 99%

The effect of a parallel free surface upon a submerged shallow synthetic jet

et al. 2020

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The interaction of a submerged shallow synthetic jet with a parallel free surface has gathered substantial interest, owing to its relevance to the operation of marine vehicles viz. ships that move close to the water surface. However, despite exhaustive research on the perturbation on a free surface, very few studies have experimentally investigated the effect of unconfined water surface height on the evolution and propagation of a submerged synthetic jet. This study experimentally investigates a synthetic jet submerged in a quiescent flow at shallow depths ejecting parallel to the free surface, through qualitative analysis and quantitative measurements. The qualitative study includes the visualization of the flow using Plane Laser Induced Fluorescence (PLIF) technique, whereas the velocity measurements are carried out by a five-beam Laser Doppler Velocimetry (LDV) probe. The primary objective of these analysis and measurements is to gain a physical insight into the characteristics of vortex ring in a synthetic jet ejected from a fixed orifice at different water depths and at varying Reynolds number. Our studies indicate that the behavior of the vortex rings drastically changes as the depth of the jet crosses a certain threshold. Although no significant change in the path of synthetic jet is observed beyond a threshold depth in our experiments, the jet trajectory shows an interesting dependence on the Reynolds number based on circulation for shallow water depths. It has been found that in the shallow depths, the vortex ring drifts upwards and interacts with the free surface at lower Reynolds number, whereas for larger Reynolds number, the vortex ring rebounds near the free surface and moves downward. Based on our observations, it can be concluded that the phenomenon of upward/downward flection of vortex rings depends both upon its circulation and water depth.

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On the flow physics and vortex behavior of rectangular orifice synthetic jets

Cited by 19 publications

References 18 publications

The mechanism of vortex bifurcation vis-à-vis axial switching in rectangular synthetic jets

The mechanism of vortex bifurcation vis-à-vis axial switching in rectangular synthetic jets

Synthetic Jet Actuators with the Same Cross-Sectional Area Orifices-Flow and Acoustic Aspects

The effect of a parallel free surface upon a submerged shallow synthetic jet

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