A new method of enhancing heat transfer in sudden expansion channel using vortex generators with toe-out and toe-in configurations by acquiring perquisites of recirculation and secondary vortex flow

Abstract

The relative positions of leading edges and trailing edges of rectangular vortex generators (VG) in the winglet form play a crucial role in modifying thermal and hydraulic boundary layers thereby affecting the heat transfer augmentation and pressure drop in a sudden expansion channel having expansion ratio (ER) 2:1. A numerical simulation was carried out for solving the momentum and energy equations of a three dimensional vortex- laminar flow (Reynolds number < 190) with a finite volume method based commercial code FLUENT 16.2. Reynolds number, angle of attack and VG configuration have been considered as influential parameters affecting the thermo-hydraulic performance of the sudden expansion channel due to the combined effect of primary recirculation and secondary vortex flow. The heat transfer enhancement along with corresponding pressure drop penalty was compared for the toe-out and toe-in configurations at various Reynolds (Re) numbers and angle of attacks (β). Eventually irrespective of configurations, rectangular winglet VGs are found to have better overall performance at β = 30° and β = 45° in both toe-out and toe-in configurations due to strong secondary vortex flow.