Session: 11-45-01: Applications of Computational Heat Transfer

Paper Number: 99760

99760 - Three-Dimensional Computational Modeling of Forced Convection in Slotted Wavy Fin Cores 

Wavy fin cores provide enhanced convective heat transfer compared to plain fins not only through higher surface area but also more dominantly by the presence of swirl flow and early onset of turbulence. There is enhancement of heat transfer in both the laminar and turbulent regimes. In a continuous wavy channel, a strong recirculation zone is observed in the trough region and high local pressures are present at the flow reattachment locations. In the laminar regime, flow stagnation occurs at the recirculation zone in the trough region, which moderates the increase in heat transfer. In the turbulent regime, the heat transfer is improved because of flow recirculation, which aids in the turbulent mixing of the fluid. Furthermore, there is increased pressure drop penalty associated with the flow-through continuous wavy fin cores. We have investigated slotted wavy fins in this paper to understand their potential to further improve the performance of wavy fins. Recent advances in additive manufacturing provide a method to fabricate slotted wavy fins that was not possible using conventional sheet metal processes. However, the performance of slotted wavy fins must be characterized to fully utilize the potential of new advances in additive manufacturing. 

A steady, periodically fully developed flow exposed to fin walls with uniform temperature is computationally modeled through slotted wavy fin cores. The computational model is validated by comparing numerical results for pressure drop and heat transfer for continuous wavy fins with available experimental data where excellent agreement is observed. The model is then used to characterize the thermal-hydraulic performance of the air flows (Pr ≈ 0.71 and 50 ≤ Re ≤ 4000) in slotted wavy fin cores. Results for isothermal fanning friction factor f, Colburn factor j, local temperature and velocity variations, and pressure maps are presented. The effects of the fin density and slot position on thermal-hydraulic performance are investigated. The flow path provided by the slots reduces flow recirculation in the trough region in the slotted wavy channel which increases heat transfer in the laminar regime. In the turbulent regime, the boundary layer disruption aids in the heat transfer, but the reduction of the flow recirculation reduces it. The net effect is only a small change in the overall heat transfer in the turbulent regime compared to continuous wavy fins. The friction factor f for the slotted fin channel shows a considerable drop when compared to the continuous wavy channel of the same cross-section, with a relatively small change in the associated Colburn factor j, and this provides significantly improved overall thermal-hydraulic performance.  

Presenting Author: Shubham J. Sathe University of Cincinnati

Presenting Author Biography: Shubham Sathe is a Graduate Student in the Department of Mechanical Engineering at the University of Cincinnati. He is a research assistant in Thermal Fluids and Thermal Processing Laboratory. His current research is concerned with single-phase heat transfer enhancement. Shubham’s research interests include Heat transfer enhancement, Computational fluid dynamics, Phase change heat transfer, and Heat and Mass transfer.

Authors:

Shubham J. Sathe University of Cincinnati
Milind A. Jog University of Cincinnati
Raj M. Manglik University of Cincinnati