Triangular ducts fitted with various kinds of delta-winglet type vortex generators (VGs) are commonly used to achieve compactness and heat transfer enhancement inmany industries. Successive locations of VGs on the inner surfaces of the ducts can be arranged in Common Flow Up (CFU) and Common Flow Down (CFD) orientations. In the present numerical study simultaneous effects of orientation and streamwise distance between VGs on triangular fin performance is carried out considering both global and local flow and heat transfer fields. With the configurations considered in this study, a CFD-CFU orientation and a nondimensional streamwise distance of 0.5 is determined as the best configuration. "RNG k-epsilon" turbulence model with "Enhanced wall treatment" option is determined as the best turbulence model to predict the flowfields inside the triangular ductwith built-in VGs, for Reynolds number of 5000.