Effects of gap size for parallel 45 degree angled rib turbulators
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 1 August 2016
Abstract
Purpose
Turbulent air flows within a channel with 45° angled rib turbulators on the top and bottom walls are numerically predicted using the numerical code. For the predictions, a v2-f turbulence model (velocity variance scale and elliptic relaxation factor model) is utilized. The paper aims to discuss these issues.
Design/methodology/approach
Three different rib arrangements with or without gap are investigated to present information on the effects of gap size on flow structure and heat transfer characteristics. Three-dimensional turbulent transport, and detailed flow structural characteristics are considered to provide new insight into the mechanisms which result in surface heat transfer augmentations.
Findings
Compared to the baseline rib arrangement, the numerically predicted results show that the parallel ribs with gap (where the width of the gap is two times of rib height) shows the highest local Nusselt number ratios. This is a result of locally increased vorticity distributions, as well as augmented local magnitudes of mixing, secondary flows, and turbulent transport. Local transport changes are less pronounced when the gap width of gap is 0.5 times of rib height. As a result, associated local and spatially averaged Nusselt number ratios are also lower for this arrangement.
Practical implications
Results will give improved heat transfer augmentation technologies.
Originality/value
The present investigation provides new information and insight into flow structural characteristics in a channel with rib turbulators, both with and without gaps, especially the mechanisms which result in surface heat transfer augmentations, which are not available in any other existing numerical or experimental investigation.
Keywords
Acknowledgements
This study was supported by the basic research project of the Korea Institute of Geoscience and Mineral Resources funded by the Ministry of Science, ICT, and Future Planning of Korea.
Citation
Park, J., Park, S. and Ligrani, P.M. (2016), "Effects of gap size for parallel 45 degree angled rib turbulators", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 26 No. 6, pp. 1768-1786. https://doi.org/10.1108/HFF-04-2015-0156
Publisher
:Emerald Group Publishing Limited
Copyright © 2016, Emerald Group Publishing Limited