Convergent-divergent flap pair for a turbojet engine nozzle of the variable-geometry convergent-divergent type, comprising a convergent flap, and a divergent flap mounted pivotably on the convergent flap about a pivot axis, whereby the convergent-divergent flap pair is capable of going from a first extreme angular configuration, in which the convergent flap and the divergent flap make between them a maximum salient angle, to a second extreme angular configuration, in which the convergent flap and the divergent flap make between them a minimum salient angle smaller than the maximum salient angle, wherein the convergent flap includes a respective inner wall, having a respective inner surface for channelling combustion gas and a respective outer surface, and a respective outer wall, wherein the convergent flap includes a respective cooling air circulation duct defined between the respective outer surface of the respective inner wall of the convergent flap and the respective outer wall of the convergent flap, wherein the divergent flap includes a respective inner wall which has a respective inner surface for channelling combustion gas, and a respective outer wall, wherein the divergent flap includes a respective cooling-air duct defined between the respective outer surface of the respective inner wall of the divergent flap and the respective outer wall of the divergent flap, wherein the convergent flap includes a convergent-flap contact surface in the shape of a cylinder portion, the axis of curvature of which is the pivot axis, and provided with first air passage openings opening into the respective cooling air circulation duct of the convergent flap, wherein the divergent flap includes a divergent-flap contact surface in the shape of a cylinder portion, the axis of curvature of which is the pivot axis, and provided with second air passage openings opening into the respective cooling-air duct of the divergent flap, wherein the divergent-flap contact surface is arranged directly opposite the convergent-flap contact surface, so that the divergent-flap contact surface slides along the convergent-flap contact surface when the divergent flap pivots with respect to the convergent flap, wherein the first air passage openings and the second air passage openings are shaped and positioned so that the first air passage openings are arranged directly opposite the second air passage openings, respectively, and thus place in communication the respective cooling air circulation duct of the convergent flap and the respective cooling-air duct of the divergent flap, regardless of the angular configuration adopted by the convergent-divergent flap pair. wherein the convergent flap includes a respective inner wall, having a respective inner surface for channelling combustion gas and a respective outer surface, and a respective outer wall, wherein the convergent flap includes a respective cooling air circulation duct defined between the respective outer surface of the respective inner wall of the convergent flap and the respective outer wall of the convergent flap, wherein the divergent flap includes a respective inner wall which has a respective inner surface for channelling combustion gas, and a respective outer wall, wherein the divergent flap includes a respective cooling-air duct defined between the respective outer surface of the respective inner wall of the divergent flap and the respective outer wall of the divergent flap, wherein the convergent flap includes a convergent-flap contact surface in the shape of a cylinder portion, the axis of curvature of which is the pivot axis, and provided with first air passage openings opening into the respective cooling air circulation duct of the convergent flap, wherein the divergent flap includes a divergent-flap contact surface in the shape of a cylinder portion, the axis of curvature of which is the pivot axis, and provided with second air passage openings opening into the respective cooling-air duct of the divergent flap, wherein the divergent-flap contact surface is arranged directly opposite the convergent-flap contact surface, so that the divergent-flap contact surface slides along the convergent-flap contact surface when the divergent flap pivots with respect to the convergent flap, wherein the first air passage openings and the second air passage openings are shaped and positioned so that the first air passage openings are arranged directly opposite the second air passage openings, respectively, and thus place in communication the respective cooling air circulation duct of the convergent flap and the respective cooling-air duct of the divergent flap, regardless of the angular configuration adopted by the convergent-divergent flap pair.