Abstract
The jet impingement phenomenon plays an important role among the heat transfer intensification methods. Very often its application and analyses refer to simple flat surfaces, while there is a lack of information in the literature for cases addressing curved surfaces. In the present work, the single jet impingement on the non-flat (concave and convex) surface is studied for a wide range of geometries, which originate from the mini-jet heat-exchanger design. The numerical simulations were performed by an advanced ζ-f turbulence model implemented in the open-source OpenFOAM (ESI-OpenCFD Ltd, Bracknell, United Kingdom) code. Noticeable differences in the phenomena occurring on the convex and concave surfaces were identified in the stagnation zone. Besides, the existence and location of the secondary peak in the Nusselt number distribution differed between the cases. These distributions were influenced by the shape of geometry, which determined flow characteristics and resulting heat transfer performance. The origins of these differences were looked at in the turbulence characteristics close to the impinged surface of the stagnations zone and its vicinity, where turbulence kinetic energy and enstrophy were analysed. It was stated that the differences are already noticeable for the single jet impingement case, but they might sum up when multiple jets are considered. Therefore, here presented results would be important for the analysis of the overall unit of mentioned mini-jets heat-exchanger.
Highlights
IntroductionBetween numerous turbulence-related cases that are considered numerically, the jet impingement is an example of the phenomenon that despite the development of various computational methods and many scientists involved, still causes problems, even though its analyses started as early as just after the Second World War [1]
These distributions were influenced by the shape of geometry, which determined flow characteristics and resulting heat transfer performance
It was stated that the differences are already noticeable for the single jet impingement case, but they might sum up when multiple jets are considered
Summary
Between numerous turbulence-related cases that are considered numerically, the jet impingement is an example of the phenomenon that despite the development of various computational methods and many scientists involved, still causes problems, even though its analyses started as early as just after the Second World War [1]. Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS)-based methods, previously applied for analyses of particular, simple cases of low Reynolds number, have already become available for complex flows, including for example additional heat transfer or crossflow phenomena. They still are important due to significantly lower computational time, sufficient accuracy and common availability [2,3]
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