CFD Investigation of Thermal Characteristics for a Dual Jet with a Parallel Co-flow

Tanmoy Mondal; Nidhal Hnaien; Mariem Ajmi; Kouather Ghachem; Lioua Kolsi

doi:10.1021/acsomega.2c00609

CFD Investigation of Thermal Characteristics for a Dual Jet with a Parallel Co-flow

ACS Omega. 2022 Aug 1;7(32):27864-27875. doi: 10.1021/acsomega.2c00609. eCollection 2022 Aug 16.

Authors

Tanmoy Mondal¹, Nidhal Hnaien², Mariem Ajmi³, Kouather Ghachem⁴, Lioua Kolsi⁵

Affiliations

¹ Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh 211004, India.
² Laboratory of Thermal Processes, Research and Technology Centre of Energy, Hammam Lif 2050, Tunisia.
³ Energy Engineering Department, Laboratory of Metrology and Energy Systems, University of Monastir, National Engineering School of Monastir, Monastir 5019, Tunisia.
⁴ Department of Industrial Engineering and Systems, College of Engineering, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia.
⁵ University of Ha'il, Ha'il City 81451, Saudi Arabia.

Abstract

A combined turbulent wall jet and offset jet (also known as the dual jet) with and without the presence of a parallel co-flow stream is studied. The standard k-ω turbulence model is used to predict the turbulent flow. The study focuses on the effects of the co-flow velocity (CFV) on the heat-transfer characteristics of the dual jet flow with the bottom wall maintained at a constant wall temperature. The CFV is varied up to 40% of the jet inlet velocity, and the height of the offset jet is varied from 5 to 11 times the jet width with the inlet Reynolds number taken as 15,000. The heat-transfer results reveal that the local Nusselt number (Nu _x ) along the bottom wall exhibits a peak at the immediate downstream of the nozzle exit, followed by a continuous decay in the rest of the converging region before showing a small rise for a short streamwise distance in the merging region. Further downstream, in the combined region, Nu _x gradually decreases with the downstream distance. Except the merging region, no influence of co-flow is observed in the other two flow zones (converging and combined regions). In the merging region, for a given offset ratio (OR), Nu _x remains nearly constant for a certain axial distance, and it decreases as the CFV increases. As a result of the increase in the CFV, the average Nusselt number decreases, indicating a reduction in overall convective heat transfer for higher values of the CFV. A regression analysis among the average Nusselt number (), CFV, and OR results in a correlation function in the form of within the range OR = 5-11 and CFV = 0-40%.