Thermal and Hydrodynamic Phenomena in the Stagnation Zone—Impact of the Inlet Turbulence Characteristics on the Numerical Analyses

Tomasz Kura, Jan Wajs, Elzbieta Fornalik-Wajs, Sasa Kenjeres and Sebastian Gurgul
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Tomasz Kura: Department of Fundamental Research in Energy Engineering, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland
Jan Wajs: Department of Energy and Industrial Apparatus, Faculty of Mechanical Engineering, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
Elzbieta Fornalik-Wajs: Department of Fundamental Research in Energy Engineering, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland
Sasa Kenjeres: Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, The Netherlands
Sebastian Gurgul: Department of Fundamental Research in Energy Engineering, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland

Energies, 2020, vol. 14, issue 1, 1-20

Abstract: One of the methods of heat transfer enhancement is utilization of the turbulent impinging jets, which were recently applied, for example, in the heat exchangers. Their positive impact on the heat transfer performance was proven, but many questions related to the origin of this impact are still unanswered. In general, the wall-jet interaction and the near-wall turbulence are supposed to be its main reason, but their accurate numerical analysis is still very challenging. The authors’ aim was to construct the numerical model which can represent the real phenomena with good or very good accuracy. Starting with an analysis of single jet and obtaining the agreement with experimental data, it will be possible to extend the model towards the whole minijets heat exchanger. The OpenFOAM software, Bracknell, UK was used for that purpose, with our own implementation of the ζ - f turbulence model. The most difficult area to model is the stagnation region, where the thermal effects are the most intensive and, at the same time, strongly affected by the conditions in the pipe/nozzle/orifice of various size (conventional, mini, micro), from which the jet is injected. In the following article, summary of authors’ findings, regarding significance of the velocity profile and turbulence intensity at the jet place of discharge are presented. In addition, qualitative analysis of the heat transfer enhancement is included, in relation to the inlet conditions. In the stagnation point, Nusselt number differences reached the 10%, while, in general, its discrepancy in relation to inlet conditions was up to 23%.

Keywords: jet impingement; heat transfer enhancement; turbulence characteristics; ζ - f RANS model; OpenFoam (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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