Session: 12-08-02: Computational Heat Transfer and Applications II

Paper Number: 166560

Three-Dimensional Computational Modeling of Enhanced Forced Convection in Offset Slotted Wavy Plate-Fin Cores 

Conventional wavy fins provide superior convective heat transfer performance compared to plain fins, due to their increased surface area, surface curvature-induced swirl, and early onset of turbulence. Building on this, the offset wavy fin design integrates the sinusoidal wavy channel and offset-strip geometry, to further improve the thermal performance. These fins are developed to disrupt the boundary layer and to promote flow mixing; however, this comes at the cost of a significant pressure drop penalty. This tradeoff is primarily due to offsetting and flow recirculation, especially in the trough region of the wave. This study explores the offset slotted wavy fins to address these limitations. In doing so, the effects of slow position on the flow recirculation are examined, which may lead to improvement in heat transfer and/or reduction in the pressure drop penalty. Recent breakthroughs in additive manufacturing techniques have provided a way to fabricate such complex geometries, which were not feasible through traditional manufacturing methods. Therefore, a comprehensive assessment of offset slotted wavy fins is essential to fully exploit these advances in additive manufacturing techniques.

A well-validated three-dimensional numerical model employing a pressure-based solver with a coupled scheme is used to simulate airflow (Pr ≈ 0.71 and 50 ≤ Re ≤ 4000) over offset slotted wavy fins under steady, periodically fully developed flow with fin walls at uniform temperature. The computational domain is discretized using a structured hexahedral mesh, which offers high resolution, and better convergence over unstructured mesh. Additionally, the mesh is further refined near the walls to accurately capture the sharp gradients. A rigorous grid independence study is conducted to determine the optimal grid size that balances accuracy and computational resources. Simulations span over Reynold number (Re) from 50 to 4000, covering laminar, transitional, and turbulent regimes. At low Re, a laminar model is used; in contrast, in turbulent regimes, the flow is resolved using the SST k-ω model for its accuracy in capturing flow separation phenomenon and adverse pressure gradients. The local temperature, velocity variations, and pressure fields, and associated heat transfer coefficient and friction drag (Colburn factor j and Isothermal fanning friction factor f) are reported. The effects of offset-slot positions (characterized by phase angle β) on flow dynamics and thermal performance are examined over the entire flow regime. The overall thermal-hydraulic performance of these novel fins is compared with the unslotted offset wavy fins in order to evaluate the relative enhancement behavior. This is quantified by an appropriate enhanced performance evaluation criteria (PEC).

Presenting Author: Shubham 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 focuses primarily on 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 Sathe University of Cincinnati
Raj M. Manglik University of Cincinnati
Milind A. Jog University of Cincinnati