Visualization of a free and impinging round jet

Popiel, C. O.; Trass, O.

doi:10.1016/0894-1777(91)90043-q

Cited by 162 publications

(73 citation statements)

References 21 publications

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“…Initially motivated by vertical take-off and landing applications (Bradshaw and Love 1959) for thrust generation, interest has more recently focused on the large heat and mass transfer coefficients achieved by impinging jets (Donaldson et al 1971;Martin 1977;Popiel and Trass 1991;Cornaro et al 1999). Confined impinging jets have received special attention Garimella 1997, 1998;Morris and Garimella 1998;Garimella 2000) in view of their applicability to electronics cooling.…”

Section: Introductionmentioning

confidence: 99%

Stereo-PIV measurements of vapor-induced flow modifications in confined jet impingement boiling

Rau

Guo

Vlachos

et al. 2016

International Journal of Multiphase Flow

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Section: Introductionmentioning

confidence: 99%

Stereo-PIV measurements of vapor-induced flow modifications in confined jet impingement boiling

Rau

Guo

Vlachos

et al. 2016

International Journal of Multiphase Flow

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“…In the case of the reference round jet, the origin of the secondary peak in Sh distribution could be related, as for Nu distribution, to the reattachment of a recirculation bubble [19][20][21].…”

Section: Mass Transfer Distributionsmentioning

confidence: 99%

“…The secondary peak is either attributed to the transition from laminar to turbulent boundary layer in the wall jet region [11,18] or to the unsteady separation of the counter-rotating secondary vortices that form near the wall bellow primary K-H vortices [19,20]. Carlomagno and Andrea [21] give in their recent review of impinging jets a comprehensive description of secondary vortex dynamics.…”

Section: Introductionmentioning

confidence: 99%

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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“…W hen this wire is placed in the p ath of a flow, for instance from an impinging jet, the smoke is carried by th e fluid flow and produces an image of the flow. Visualisation of th e fluid flow w'hich emerges from an impinging jet nozzle with a contoured geometry was explored by Popiel and Trass [87] and Baydar and Ozmen [88].…”

Section: Sm Oke-w Irementioning

confidence: 99%

“…Trass [87] of an impinging jet w ith a flat surface. The resulting images give incredible insight into the development of vortex m aturity as th e jet fluid mixes with th e am bient air surrounding it; an exam ple of such is shown in figure 2.41.…”

Section: Figure 241' Illustration O F Je T Developm Ent At H /D = 1 mentioning

confidence: 99%

Heat Transfer Characteristics of Swirling Impinging Jets

Brown

Murray

Persoons

et al. 2009

Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C

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Impinging jets are used in a wide number of industrial cooling applications due to their high heat and mass transfer abilities. The current research is concerned with the effect of swirl on the heat transfer characteristics of jet impingement cooling. Two inserts were designed order to generate swirling flow. These two designs, “Swirl Insert A” and “Swirl Insert B”, were tested at various Reynolds numbers, between 8000 and 16000 inclusive, and at H/D = 0.5 and 1. The jet was directed downwards onto a 25μm thick stainless steel foil which was ohmically heated. Images were recorded using a thermal imaging camera focused on the underside of the foil. These images were then analysed using Matlab and the Nusselt number profile was obtained. It was found that, while both swirl inserts establish an improvement in the heat transfer by comparison to that of a jet with no swirl, the “Swirl Insert B” design performed better that the “Swirl Insert A” design for high Reynolds number at H/D = 0.5 and consistently for H/D = 1. It was also discovered that, while both the “No Insert” and “Swirl Insert B” results did not change dramatically with an alteration in H/D, “Swirl Insert A” decreased by ∼10%.

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Visualization of a free and impinging round jet

Cited by 162 publications

References 21 publications

Stereo-PIV measurements of vapor-induced flow modifications in confined jet impingement boiling

Stereo-PIV measurements of vapor-induced flow modifications in confined jet impingement boiling

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

Heat Transfer Characteristics of Swirling Impinging Jets

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