Experimental investigation of influence of Reynolds number on synthetic jet vortex rings impinging onto a solid wall

Xu, Yang; He, GuoSheng; Kulkarni, Varun; Wang, Jinjun

doi:10.1007/s00348-016-2287-5

Cited by 26 publications

(12 citation statements)

References 33 publications

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“…There are two commonly used methods for forming a vortex ring: (a) a piston‐cylinder (see Figure 1B), which forms a vortex ring based on the reciprocating motion of a piston; and (b) a synthetic jet actuator (see Figure 1C), which forms a vortex ring by using the vibrations of a piezoelectric lead zirconate titanate (PZT) diaphragm to cause rapid volume changes in a cavity. The piston‐cylinder is often used in water experiments; the piston moves at a lower speed, and the formed vortex ring has a low turbulence and speed, which is suitable for the study of its characteristics 28–30 . Meanwhile, the synthetic jet actuator is usually small in scale, and the formed vortex ring has a high turbulence, moves at a faster velocity, and has a smaller volume.…”

Section: Methodsmentioning

confidence: 99%

“…The piston-cylinder is often used in water experiments; the piston moves at a lower speed, and the formed vortex ring has a low turbulence and speed, which is suitable for the study of its characteristics. [28][29][30] Meanwhile, the synthetic jet actuator is usually small in scale, and the formed vortex ring has a high turbulence, moves at a faster velocity, and has a smaller volume. As such, these systems are widely used for drag reduction, heat transfer enhancement, and mixing control.…”

Section: High Ventilation Efficiencymentioning

confidence: 99%

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Potential application of using vortex ring for personalized ventilation

et al. 2020

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People spend most of their time indoors, making Indoor Air Quality an important consideration for the health of room occupants. However, the energy consumption of heating, venting, and air conditioning (HVAC) systems accounts for 10-20% of the total primary energy 1,2 and requires that the ventilation system meets challenges in regard to both improving the Indoor Air Quality and the energy saving. As a consequence, personalized ventilation (PV) has been widely considered and studied. In contrast to general ventilation, the purpose of PV systems is to create local micro-environments around people. Studies have shown that under reasonable design and use conditions, PV systems can maintain good Indoor Air Quality and reduce energy consumption. 3-7 Existing PV systems consist of placing an air terminal device (ATD) near a breathing zone (BZ) to supply conditioned fresh air directly into the zone, and to avoid dilution with old indoor air. The primary categories of PV systems include desk-mounted, chair-direct, partitioned, chair-mounted, floor-based, and overhead jet systems. 8

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Section: Methodsmentioning

confidence: 99%

Section: High Ventilation Efficiencymentioning

confidence: 99%

Potential application of using vortex ring for personalized ventilation

et al. 2020

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“…1987; Orlandi & Verzicco 1993; Cheng, Lou & Luo 2010; Xu et al. 2017). However, the generation mechanism for the latter is attributed to boundary layer separation under the adverse pressure gradient (Walker et al.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the interaction of synthetic jet vortex rings with a stratified interface

Wang

Feng

2022

J. Fluid Mech.

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The vortex dynamics in a stratified environment is of fundamental importance in various flow systems, however, the mechanism of successive vortex–interface interactions remains not fully understood. This study investigates synthetic jet vortex rings impinging on a water–oil interface by experiment and numerical simulation. Two cases in the laminar and transitional regimes are concerned with the Froude number (Fr) of 0.35 and 0.82, respectively. The vortex rings for the two cases follow a similar evolution with three distinct stages, including vortex free-travel, vortex–interface interaction and vortex stretching. As products of the vortex–interface interaction, the secondary vortex rings are baroclinically generated in both water and oil followed by the formation of hairpin vortices through azimuthal deformation. Distinguished from an isolated vortex–interface interaction, complex interactions occur between the primary vortex ring and hairpin vortices, which can enhance the vortex ring instability in existence of the stratification for the laminar case. However, the vortex ring instability for the transitional case can develop earlier due to nonlinear effects with increasing Reynolds number. The spatio-temporal properties of the interface deformation and interfacial waves are analysed. The maximum penetration height of vortex rings scales with Fr2 as that for the isolated situation. Particularly, the transitional case is found to produce destabilization of the interfacial waves at a further radial location. The mechanism is revealed by connecting the dynamics of the vortex and the interface, which can be attributed to the radial development of perturbances stemming from the vortex ring instability under strong vortex–interface interaction.

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“…Furthermore, several studies made use of hot-wire anemometry (Chou et al, 2002), microphone measurements and multi-channel pressure transducer measurements (Hall and Ewing, 2006) and polarographic method (EI Hassan et al, 2012;Kristiawan et al, 2012) in the investigation of impinging jets. More recently, digital particle image velocimetry (DPIV) technique has seen increasing use as a reliable quantitative technique to provide accurate measurements of the flow fields for various jet impingement scenarios, as demonstrated by Violato et al (2012), Meslem et al (2013), Xu et al (2017) and Guo et al (2017).…”

Section: Introductionmentioning

confidence: 99%