The augmentation of convective heat transfer of a turbulent flow using deltawinglet vortex generators (VG) in a triangular duct was experimentally investigated. Two side walls of the heated test section are electrically heated with a constant heat flux while the lower wall is indirectly heated. Single, double, and triple pairs of VG are utilized. Each pair of VG was punched on one wall of the test duct. The effects of the number of VG pairs, the VG angle of attack, the VG location from the leading edge of the test duct, the VG geometry, and Reynolds number are examined in this paper. The results indicate that the Nusselt number and friction factor are relatively proportional to the size, number, and the inclination angle of the VG. The Nusselt number increases and the friction factor decreases as the Reynolds number increases. The present results were compared with the available literature and they show good agreement. Correlation equations of Nusselt number and friction factor for turbulent flow are developed, for the cases studied, as a function of Reynolds number and VG angle of attack.

An experimental investigation is performed to study the friction factor ( f ) and convection heat transfer coefficient (h) behavior in an asymmetrically heated equilateral triangular duct by using delta-winglets vortex generators which are embedded in a turbulent boundary layer. Two side walls of the heated test section are electrically heated with a constant heat flux, whereas the lower wall is indirectly heated. Reynolds number (Re) is ranged from (23,000) to (58,000). Two sizes and three attack angles of vortex generators are studied here for three cases; single, double, and treble pairs of generators. Each pair was supported in one wall of the test section at the various locations from the leading edge. The indicated results that friction factor ( f )and Nusselt number (Nu) are relatively proportion with the size, number and the inclination angle of the generators. The ( f ) decreases as airflow rate increases whereas Nu number increases. The present data of ( f ) is less than the data of Chegini by about (6.5 %) and overpredicts the data of Altemani by about (1.7 %).