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Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications

In this paper, a numerical investigation was performed of an air jet incident that normally occurs on a horizontal heated plane. Analysis of flow physics and entropy generation due to heat and friction is included using a simple easy-to-manufacture, surface roughening element: a circular rib concent...

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Autores principales: Alenezi, Abdulrahman, Almutairi, Abdulrahman, Alhajeri, Hamad, Almekmesh, Saad F., Alzuwayer, Bashar B.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9140955/
https://www.ncbi.nlm.nih.gov/pubmed/35626546
http://dx.doi.org/10.3390/e24050661
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author Alenezi, Abdulrahman
Almutairi, Abdulrahman
Alhajeri, Hamad
Almekmesh, Saad F.
Alzuwayer, Bashar B.
author_facet Alenezi, Abdulrahman
Almutairi, Abdulrahman
Alhajeri, Hamad
Almekmesh, Saad F.
Alzuwayer, Bashar B.
author_sort Alenezi, Abdulrahman
collection PubMed
description In this paper, a numerical investigation was performed of an air jet incident that normally occurs on a horizontal heated plane. Analysis of flow physics and entropy generation due to heat and friction is included using a simple easy-to-manufacture, surface roughening element: a circular rib concentric with the air jet. This study shows how varying the locations and dimensions of the rib can deliver a favorable trade-off between entropy generation and flow parameters, such as vortex generation and heat transfer. The performance of the roughness element was tested at three different radii; R/D = 1, 1.5 and 2, where D was the jet hydraulic diameter and R was the radial distance from the geometric center. At each location, the normalized rib height (e/D) was increased from 0.019 to 0.074 based on an increment of (e/D) = 0.019. The jet-to-target distance was H/D = 6 and the jet Reynolds number (Re) ranged from 10,000 to 50,000 Re, which was obtained from the jet hydraulic diameter (D), and the jet exit velocity (U). All results are presented in the form of entropy generation due to friction and heat exchange, as well as the total entropy generated. A detailed comparison of flow physics is presented for all ribs and compared with the baseline case of a smooth surface. The results show that at higher Reynolds numbers, adding a rib of a suitable height reduced the total entropy ([Formula: see text]) by 31% compared to the no rib case. In addition, with ribs of heights 0.019, 0.037 and 0.054, respectively, the entropy generated by friction ([Formula: see text]) was greater than that due to heat exchange ([Formula: see text]) by about 42%, 26% and 4%, respectively. The rib of height e/D = 0.074 produced the minimum S(t) at R/D = 1. As for varying R/D, varying rib location and Re values had a noticeable impact on [Formula: see text] , [Formula: see text] and ([Formula: see text]). Placing the rib at R/D = 1 gave the highest total entropy generation ([Formula: see text]) followed by R/D = 1.5 for all Re. Finally, the Bejan number increased as both rib height and rib location increased.
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spelling pubmed-91409552022-05-28 Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications Alenezi, Abdulrahman Almutairi, Abdulrahman Alhajeri, Hamad Almekmesh, Saad F. Alzuwayer, Bashar B. Entropy (Basel) Article In this paper, a numerical investigation was performed of an air jet incident that normally occurs on a horizontal heated plane. Analysis of flow physics and entropy generation due to heat and friction is included using a simple easy-to-manufacture, surface roughening element: a circular rib concentric with the air jet. This study shows how varying the locations and dimensions of the rib can deliver a favorable trade-off between entropy generation and flow parameters, such as vortex generation and heat transfer. The performance of the roughness element was tested at three different radii; R/D = 1, 1.5 and 2, where D was the jet hydraulic diameter and R was the radial distance from the geometric center. At each location, the normalized rib height (e/D) was increased from 0.019 to 0.074 based on an increment of (e/D) = 0.019. The jet-to-target distance was H/D = 6 and the jet Reynolds number (Re) ranged from 10,000 to 50,000 Re, which was obtained from the jet hydraulic diameter (D), and the jet exit velocity (U). All results are presented in the form of entropy generation due to friction and heat exchange, as well as the total entropy generated. A detailed comparison of flow physics is presented for all ribs and compared with the baseline case of a smooth surface. The results show that at higher Reynolds numbers, adding a rib of a suitable height reduced the total entropy ([Formula: see text]) by 31% compared to the no rib case. In addition, with ribs of heights 0.019, 0.037 and 0.054, respectively, the entropy generated by friction ([Formula: see text]) was greater than that due to heat exchange ([Formula: see text]) by about 42%, 26% and 4%, respectively. The rib of height e/D = 0.074 produced the minimum S(t) at R/D = 1. As for varying R/D, varying rib location and Re values had a noticeable impact on [Formula: see text] , [Formula: see text] and ([Formula: see text]). Placing the rib at R/D = 1 gave the highest total entropy generation ([Formula: see text]) followed by R/D = 1.5 for all Re. Finally, the Bejan number increased as both rib height and rib location increased. MDPI 2022-05-08 /pmc/articles/PMC9140955/ /pubmed/35626546 http://dx.doi.org/10.3390/e24050661 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Alenezi, Abdulrahman
Almutairi, Abdulrahman
Alhajeri, Hamad
Almekmesh, Saad F.
Alzuwayer, Bashar B.
Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title_full Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title_fullStr Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title_full_unstemmed Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title_short Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications
title_sort impact of surface roughness on flow physics and entropy generation in jet impingement applications
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9140955/
https://www.ncbi.nlm.nih.gov/pubmed/35626546
http://dx.doi.org/10.3390/e24050661
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