Multi objective optimization of vortex generators for heat transfer enhancement using large design space exploration

Abstract

In many applications, convective heat transfer enhancement is readily achieved by generating streamwise vortices and coherent flow structures using Vortex Generators (VG's) such as in multifunctional heat exchangers/reactors. Shape optimization of the VG's have been carried out over the last decades to find enhanced designs. Meanwhile, the design variables were limited to two or three such as angle of attack, roll angle and shape factor. In the present study, optimization using a large space exploration design via multiobjective function are conducted to find optimal VG designs. Simulations are performed over the VG shape in a rectangular parallel plate channels under forced convection laminar flow regime. Firstly the numerical results are validated versus experimental and numerical data from the open literature. Then, seven design parameters are considered with different incremental values which are: Attack Angle (α), Roll Angle (β), Base Angles (γ1 and γ2), Height (h), Length (l), and Shape Length (SL). Based on the new optimization study, a novel enhanced VG is found with thermal enhancement factor 35% relative to an empty channel and 14% better than literature results. Local analysis of the flow structure and heat transfer processes are conducted for the new optimized VG and for other classical VG shapes.