Primary and secondary vortical structures contribution in the entrainment of low Reynolds number jet flows

Năstase, Ilinca; Meslem, Amina; Gervais, Philippe

doi:10.1007/s00348-008-0488-2

Cited by 45 publications

(40 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mean streamwise profile of the convergent nozzle is flat (Fig.4 a) while for the Cross-Shaped nozzles, a two-step distribution characterized the major plane (Fig.4 a). The same behaviour was also observed by Nastase et al [52] in a free jet from a cross-shaped orifice and by Hu et al [53] in a six-lobed nozzle jet. This is because in the lobed jets, the major plane has two shear layers: the inner shear layer between the jet central core and the lobes, and the outer shear layer between the jet flow and its ambience.…”

Section: Initial Conditionssupporting

confidence: 83%

“…Large spreading was also seen in the CO/P nozzle jet, although not in the MP, as was the case for the CO/H nozzle, but in the mP due to the axis-switching phenomenon. Such a phenomena has been observed in our previous studies of free planar lobed orifice jets [52,55] and is reported in the recent numerical study on a low aspect ratio rectangular impinging jet of Gorman et al [57]. It should be noted that the axis-switching phenomenon is not more reported in the literature in the case of the impinging jets.…”

Section: Flow Characteristicssupporting

confidence: 77%

“…It should be noted that the axis-switching process in the present study could not be completed due to the presence of the target wall at H = 2De from the nozzle. Indeed, it was observed that the axis-switching process ended at 3De from the exit in the free air-air Cross-Shaped jet from same orifices [52,55]. Around 2 De from the nozzle exit, the free CO/P nozzle jet [55] and the impinging CO/P nozzle jet (present study, see Fig.…”

Section: Flow Characteristicssupporting

confidence: 50%

“…In the CO/P nozzle jet, the maximum value in the region around r =1De was about 16% lower than that of the reference convergent nozzle jet. This is probably due to the fact that the lobed CO/P nozzle generates more induction than the round nozzle [52,55]. In the second region of the CO/P nozzle jet, the maximum radial velocity in mP was higher than that in MP.…”

mentioning

confidence: 95%

“…In the second region of the CO/P nozzle jet, the maximum radial velocity in mP was higher than that in MP. This behaviour is probably due to the contribution of the streamwise structures which are developed in the troughs of the CO/P nozzle [52,55].…”

mentioning

confidence: 99%

See 4 more Smart Citations

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

et al. 2015

Self Cite

View full text Add to dashboard Cite

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

show abstract

Section: Initial Conditionssupporting

confidence: 83%

Section: Flow Characteristicssupporting

confidence: 77%

Section: Flow Characteristicssupporting

confidence: 50%

mentioning

confidence: 95%

mentioning

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

Self Cite

View full text Add to dashboard Cite

show abstract

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

et al. 2015

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Vortex dynamics and mass entrainment in turbulent lobed jets with and without lobe deflection angles

Năstase

Meslem

2009

Exp Fluids

View full text Add to dashboard Cite

Primary and secondary vortical structures contribution in the entrainment of low Reynolds number jet flows

Cited by 45 publications

References 12 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

Vortex dynamics and mass entrainment in turbulent lobed jets with and without lobe deflection angles

Contact Info

Product

Resources

About