Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

Hassan, Mouhammad El; Assoum, Hassan; Sobolı́k, V.; Vétel, Jérôme; Abed-Meraïm, Kamel; Garon, André; Sakout, Anas

doi:10.1007/s00348-012-1269-5

Cited by 67 publications

(37 citation statements)

References 53 publications

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“…For this reason and in order to explain the strong wall/flow interaction process in the inclined impinging jet flow, Figure 13 shows instances of the instantaneous (a) and time-averaged (b) absolute wall shear stress |τ w | induced by the inclined jet on the wall. Similar to fully-developed turbulent jets impinging perpendicularly on a solid surface, wall shear stresses are very low at the stagnation region and peak in its immediate vicinity (for a comparison, see, e.g., [5,49,50]). It is interesting to observe that, in the case of a 45 • inclination angle, the wall shear stress is predominantly concentrated at the secondary opposed wall jet region (ζ < 0), where the direction of the flow changes suddenly and the fluid is subject to a high acceleration in the wall-parallel direction.…”

Section: Near-wall Shear Stressmentioning

confidence: 99%

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Ries

Rißmann

et al. 2018

Fluids

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Abstract:In the present paper, direct numerical simulation (DNS) and particle image velocimetry (PIV) have been applied complementarily in order to generate a database of near-wall turbulence properties of a highly turbulent jet impinging on a solid surface under different inclination angles. Thereby, the main focus is placed on an impingement angle of 45 • , since it represents a good generic benchmark test case for a wide range of technical fluid flow applications. This specific configuration features very complex flow properties including the presence of a stagnation point, development of the shear boundary layer and strong streamline curvature. In particular, this database includes near-wall turbulence statistics along with mean and rms velocities, budget terms in the turbulent kinetic energy equation, anisotropy invariant maps, turbulent length/time scales and near-wall shear stresses. These properties are useful for the validation of near-wall modeling approaches in the context of Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulations (LES). From this study, in which further impingement angles (0 • , 90 • ) have been considered in the experiments only, it turns out that (1) the production of turbulent kinetic energy appears negative at the stagnation point for an impingement angle other than 0 • and is balanced predominantly by pressure-related diffusion, (2) quasi-coherent thin streaks with large characteristic time scales appear at the stagnation region, while the organization of the flow is predominantly toroidal further downstream, and (3) near-wall shear stresses are low at the stagnation region and intense in regions where the direction of the flow changes suddenly.

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Section: Near-wall Shear Stressmentioning

confidence: 99%

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Ries

Rißmann

et al. 2018

Fluids

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“…The small working electrode is situated at the impinged surface and the size of the diffusion current is proportional to the molar flux of ion exchange and, at some conditions, it is also proportional to the heat transfer coefficient. The limiting diffusion current can be used to determine the shear stress (rate) at the location of the working electrode, see for example [17][18][19][20]. Using the analogy between mass and heat transfer, the heat transfer characteristics can be determined [21].…”

Section: Experimental Methodsmentioning

confidence: 99%

Heat transfer measurements and CFD simulations of an impinging jet

Petera

Dostál

2016

EPJ Web of Conferences

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Abstract. Heat transport in impinging jets makes a part of many experimental and numerical studies because some similarities can be identified between a pure impingement jet and industrial processes like, for example, the heat transfer at the bottom of an agitated vessel. In this paper, experimental results based on measuring the response to heat flux oscillations applied to the heat transfer surface are compared with CFD simulations. The computational cost of a LES-based approach is usually too high therefore a comparison with less computationally expensive RANS-based turbulence models is made in this paper and a possible improvement of implementing an anisotropic explicit algebraic model for the turbulent heat flux model is evaluated.

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“…This technique has been extensively described in Kristiawan et al [44], El Hassan et al [41], and Meslem et al [48], so only a brief summary will be given here. The technique was developed to measure the average rate of mass transfer and their fluctuations on a wall.…”

Section: Wall Shear Ratementioning

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%

“…It is reported in the literature that the first peak in γ -distribution or in Nu -distribution is related to the impingement of the K-H vortices on the wall [23,35], whereas the secondary peak is due to secondary counter-rotating vortices and to the associated turbulence produced [37,41], or to a transition from a laminar to a turbulent boundary layer [20,36]. In the context of the present study, the first and second peaks of γ -distribution in the major plane of the CO/H nozzle jet are related to the persistent double shear layer in this plane (Fig.…”

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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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Experimental investigation of the wall shear stress and the vortex dynamics in a circular impinging jet

Cited by 67 publications

References 53 publications

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Heat transfer measurements and CFD simulations of an impinging jet

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

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