Enhancing microchannel heat transfer using passive vortex generators with a cylinder and staggered flexible beams

A heat transfer system is proposed to enhance the thermal performance of a microchannel by positioning a rigid cylinder upstream of the staggered flexible beams as passive vortex generators. By using a fluid-structure-thermal coupling solver, the effects of the number and spacing of flexible beams on specific physical quantities, such as the local Nusselt number and Colburn factor, were investigated. The results indicate that the periodic pressure variations induced by the wake of the cylinder cause vibrations of the flexible beams, which generate stronger vortices and enhance flow mixing. The staggered flexible beams make vortices closer to the wall, leading to more significant disturbances to the thermal boundary layer and improving convective heat transfer. Further analysis shows that a sufficient number of flexible beams are necessary to effectively perturb the far-field thermal boundary layer due to the dissipation of wake vortices, although this also increases the pressure drop. The spacing of the flexible beams affects the strength of the local vortices, and appropriate spacing increases the intensity of the vortices. By considering both heat transfer performance and energy consumption, the optimal configuration of passive vortex generators is identified in this study.