Three-dimensional vortex dynamics and convective heat transfer in circular and chevron impinging jets

Violato, Daniele; Ianiro, Andrea; Cardone, Gennaro; Scarano, Fulvio

doi:10.1016/j.ijheatfluidflow.2012.06.003

Cited by 121 publications

(51 citation statements)

References 43 publications

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“…For a high Reynolds number (Re = 41 600) and a nozzle-to-wall distance of H < 4D, two peaks were found in γ (or in wall shear stress τ = µ .γ ) distribution [38]. As for the Nu -distribution [20,23,26,35], the first peak in γ -distribution appeared at a distance from the stagnation point ranging from r = 0.56D to r = 0.74D, while the second peak was located at r = 1.9D [38,40] . The fact that peak-locations in γ -distribution closely match with those of Nu -distribution suggests that the wall shear stress and the local heat/mass transfer are closely linked.…”

Section: Introductionmentioning

confidence: 97%

“…One decade after the observation of Gardon and Akrifat [15], Popiel and Boguslawski [17] claimed that nozzle exit configuration was the most important factor affecting the stagnation point heat transfer. Despite these first very significant indications, there are only a few studies dedicated to heat/mass transfer enhancement using active [18][19][20][21] or passive jet control [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

“…The first peak corresponds to the maximum heat transfer rates and appears at the vicinity of the lateral edge of the nozzle. In some investigations the location of the first peak for H/D < 4 was observed from r = 0.5D to r = 0.7D [20,23,26,35]. This peak was attributed to the high turbulence intensity at the nozzle edge and to a direct impingement of large toroidal Kelvin-Helmholtz (K-H) vortices originating in the mixing region.…”

Section: Introductionmentioning

confidence: 99%

“…This peak was attributed to the high turbulence intensity at the nozzle edge and to a direct impingement of large toroidal Kelvin-Helmholtz (K-H) vortices originating in the mixing region. The secondary peak occurs at the radial distance from the stagnation point, from 1.2D to 2.5D [20,23,26,36]. The second peak was either attributed to the transition from a laminar to a turbulent boundary layer in the wall jet region [16] or to the unsteady separation of the induced secondary vortices that form near the wall 5 under primary K-H vortices [37].…”

Section: Introductionmentioning

confidence: 99%

“…The connection of the heat/mass transfer phenomena with the large-scale structures which develop in the free jet region or with the subsequent flow dynamics in the stagnation and the wall jet regions is now recognized [26,37,41,42]. Therefore, the control of large-scale structures in impinging jets is a key element in the strategy of heat/mass transfer optimization and control.…”

Section: Introductionmentioning

confidence: 99%

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Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

et al. 2015

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To cite this version:Kodjovi Sodjavi, Brice Montagné, Pierre Bragança, Amina Meslem, Florin Bode, et al.. Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles. Meccanica, Springer Verlag, 2015, pp.1-21. 10 AbstractIt is well known that the transfer of heat, mass and momentum to a wall by an impinging jet is partially linked to the way in which jet generation is realized. The organization of the vortices at the jet exit depends on the upstream conditions and on the geometry of the nozzle. Particle Image Velocimetry (PIV) and electrodiffusion techniques were used to investigate the characteristics of different impinging jets and the resulting wall shear rates and mass transfer. Two Cross-Shaped orifice jets, one produced by a plane orifice nozzle (i.e. a Cross-Shaped Orifice made on a flat Plate, CO/P) and the second by a hemispherical orifice nozzle (i.e. a Cross-Shaped Orifice made on a Hemisphere, CO/H), were compared to a reference round jet produced by a convergent nozzle. The distance between the jet exit and the target wall was equal to two nozzle equivalent diameters (De), based on the free orifice area. The Reynolds number, based on De and on the exit bulk-velocity, was 5620 for each flow. PIV measurements give an overall view of the flow characteristics in their free and wall regions. The switching-over phenomena observed in the CO/P nozzle case, and already described in the literature with similar nozzles, did not occur in the jet from the CO/H nozzle. Electrodiffusion measurements showed differences in the shape and level of radial distribution of the wall shear rates and mass transfer. One of the most important observations is the large difference in wall shear stress between the three jets. For the same exit bulk-velocity, the maximum wall shear rate in the CO/P and CO/H nozzle jets was almost two and three times higher, respectively, than that of the reference convergent jet. This higher wall shear rate is accompanied

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

et al. 2015

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Passive control of wall shear stress and mass transfer generated by submerged lobed impinging jet

et al. 2015

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Particle Image Velocimetry was used to investigate the flow field in an impinging lobed daisy hemispherical nozzle jet in comparison to its counterpart round jet, at a Reynolds number of 5620 based on the exit velocity and the equivalent diameter De of the nozzle.The limitations of the PIV technique in the vicinity of the target wall due to the laser scattering were addressed by using the electrodiffusion (ED) technique to determine the wall shear rate distribution. The distribution of the mass transfer coefficient is also obtained using the ED technique. The target wall is placed at a distance H = 2De from the plane tangent to the nozzle, at the center of the orifice. The entrainment of ambient fluid in the free jet region, which is larger in the lobed jet compared to the round jet, feeds in turn the wall jet region.The maximum wall shear rate was found significantly higher in the daisy jet, with an excess of 93% compared to the reference round jet. The maximum mass transfer is 35% higher in the former compared to the latter. Therefore, the hemispherical daisy nozzle is an excellent candidate in passive strategies to enhance local skin-friction and the subsequent local mass transfer at a constant exit Reynolds number.

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Convective heat transfer on a flat target surface impinged by pulsating jet with an additional transmission chamber

et al. 2019

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Three-dimensional vortex dynamics and convective heat transfer in circular and chevron impinging jets

Cited by 121 publications

References 43 publications

Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

Passive control of wall shear stress and mass transfer generated by submerged lobed impinging jet

Convective heat transfer on a flat target surface impinged by pulsating jet with an additional transmission chamber

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