Numerical investigation of fully developed periodic turbulent flow in a square channel fitted with 45° in-line V-baffle turbulators pointing upstream

Abstract

This paper presents numerical simulation of periodic fully developed turbulent flow and thermal characteristics in a square channel fitted with V-baffles using air as the working fluid at Re ranging from 5000 to 25000. V-baffles with an angle of attack of 45° pointing upstream are mounted in both lower and upper walls with an in-line arrangement. Effect of various baffle blockage ratios (BR=0.2, 0.4 and 0.6) and baffles pitch ratios (PR=0.5,1 and 1.5) on flow behavior and heat transfer are investigated. The results show that the V-baffle induces four counter-rotating vortices, and their core centers appear to spirally move close to each other along the baffle cavity which leads to induce better flow mixing between the core and wall flow regions. Also, V-baffle pointing upstream causes high impinging regions on the channel walls leads to higher Nusselt number rates in jet impinging areas. Higher BR and/or lower PR result in an increase in Nusselt number. Thermal enhancement factor tends to increase as BR decreases. The BR=0.2 give value of thermal enhancement factor=0.78 at the lower Re=5000. Also, lower value of PR (PR=0.5) leads to higher enhancement factor.