Heat transfer enhancement using second mode self-oscillating structures
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 16 December 2019
Issue publication date: 16 June 2020
Abstract
Purpose
In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs).
Design/methodology/approach
Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers.
Findings
For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG.
Practical implications
The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones.
Originality/value
The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.
Keywords
Citation
Ali, S., Shami, Z.A., Badran, A. and Habchi, C. (2020), "Heat transfer enhancement using second mode self-oscillating structures", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 30 No. 7, pp. 3827-3842. https://doi.org/10.1108/HFF-07-2019-0583
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited