RESUMO

Winglets are widely used to enhance heat transfer in various channels. Numerical simulations were carried out to investigate the characteristics of heat transfer enhancement and the flow resistance of five winglets including trapezoidal grooves, rectangular grooves, triangular grooves, elliptic grooves or trapezoidal bosses, which are respectively installed in a rectangular channel. The characteristics of heat transfer enhancement and flow resistance of the winglets were analyzed in terms of an integration evaluation factor, Nusselt number ratio, and friction factor ratio with the Reynolds number (Re) between 10,000 and 60,000. The channel equipped with winglets (hereafter referred to as the turbulent channel) could magnify the average convective heat transfer coefficients compared to the channel without any winglet (hereafter referred to as the smooth channel). The best heat transfer enhancement could especially be achieved by the trapezoidal boss with the Nusselt number ratio increased by 90.61−79.21% as against the smooth channel. The winglet with trapezoidal groove had the best comprehensive property among the five winglets, with the trapezoidal boss following closely by a margin of 0.32−1.73%. As a result, the winglets of trapezoidal boss are encouraged to be adopted in practical application in the case where the pressure drop of fluid flow in the channel is under permissible condition.