A transition duct includes fairings with transition duct flow passage and hollow fairing airfoils extending between outer and inner walls of fairings and means for smoothing pressure gradients along inner wall. One means is a contracting duct flow area of flow passage from leading edge of fairing airfoil to about 30% of fairing chord. Leading edges of fairing airfoil intersect outer walls aft of regions of high curvature of outer walls. Leading edges may curve axially aftwardly and radially into fairing airfoils and transition duct flow passage between radially outer and inner walls from radially outer and inner intersection points. Transition duct downstream second area/upstream first area may be greater than about 1.35. Turbine center frame may include outer ring coupled to central hub with struts extending through hollow airfoils.