LAUSR

Abstract This work numerically and experimentally studies the heat transfer performances and flow characteristics of vortex generators (VGs) in a high aspect ratio rectangular ribbed channel with the Reynolds number ranging from 20000 to 100000. The steady liquid crystal thermography (LCT) method is adopted to link the images captured by experiments and the Nusselt numbers. Four different cases combining ribs and VGs are considered, and they are compared with a case with five continuous ribs in the channel. For the first time, the effect of winglet VGs and the tetrahedral VGs on heat transfer performance are compared. Simultaneously, two different arrangements of VGs, i.e. common-flow-down VGs and common-flow-up VGs are also studied to figure out which arrangement is better for improving the heat transfer performance. Simulations are conducted to systematically compare the fluid flow and local heat transfer characteristics to reveal the underlying thermo-fluid mechanisms of the considered cases by using three-dimensional CFD numerical simulations with a verified turbulence model, i.e., the SST k-ω model in the transition state. Results indicate that in the range of 0