Numerical simulations are carried out to infer the heat transfer performances of perforated trapezoidal vortex generators (PTVG) in a turbulent regime, for Reynolds numbers ranging from 7500 to 15000. The flow geometry consists of a circular pipe fitted with seven arrays of perforated tabs, similarly, arranged as in the high efficiency vortex static mixer (HEV (TM)) used in the industry. Four configurations using the PTVG are studied, differing by the flow direction, direct or inverse, and the arrangement of the tab arrays, aligned or alternate. The flow pattern shows the presence of primary pair of counter-rotating streamwise vortices at the tip of the tabs, as well as smaller secondary vortices near the wall region, well-known as the main transfer intensification mechanism. The perforation in the tab generates a jet-like flow structure which penetrates the dead zone behind the tabs and therefore, locally enhances the heat transfer and the global performance of the device. It is found that the heat transfer relative to empty pipe is enhanced from 40 to 80%, for the same pumping power. The new proposed PTVG exhibits better performance than classical HEV (TM), especially for Reynolds numbers greater than 10,000. This study is fundamental for highlighting the effect of perforating the vortex generators on heat transfer performance. Moreover, the novel PTVG would be of great benefit to enhance commercial multifunctional heat exchangers/reactors.
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