THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

Enhanced heat transfer under the influence of coherent structure induced by arc vortex generator in square pipe flows

ABSTRACT
Experiments and numerical simulations were both performed to investigate coherent structures and heat transfer process in a square pipe turbulent flows induced by arc vortex generator (AVG). The velocity fields of induced turbulent flow was obtained by planar particle image velocimetry (PIV). The analysis of velocity profiles revealed the co-existence of various coherent structures (CS). Turbulent fluctuation quantities, such as turbulent intensities, Reynolds stress, etc. exhibited the different behaviors of fluid motions introduced by AVG. Probability density function (PDF) of swirling strength showed the complication of the vortex-rotating. Heat transfer process was simulated using large eddy simulation (LES). The results of Nusselt number (Nu) achieved the maximal improvement 57% with the use of AVG. The distribution of Nu was in good agreement with the distribution of CSs, especially hairpin vortices and subsequent secondary CS, which highlighted the influence of CSs generated by AVG on heat transfer enhancement.
KEYWORDS
PAPER SUBMITTED: 2018-06-05
PAPER REVISED: 2018-08-06
PAPER ACCEPTED: 2018-11-01
PUBLISHED ONLINE: 2019-04-14
DOI REFERENCE: https://doi.org/10.2298/TSCI180605136W
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