Abstract: A secondary-air nozzle of a two-flow jet engine having separated flows including an annular cowl element translatably mobile in an axial direction between an upstream retracted position allowing the engine to operate under direct thrust and a downstream extended position, and a grid thrust reverser including cylindrical ring sectors coaxial with the cowl element, including blades with a radial setting, and axially separated to provide radial guide passages therebetween, the cowl element opening the radial guide passages in the downstream extended position through the thrust reverser grids. The radius of the ring sectors forming the grids is not constant around the circumference of the cowl element, the radius of transverse cuts of at least one of the walls not being constant, when moving around the circumference of the cowl element, the cuts being made between the upstream edge of the cowl element and the downstream edge thereof.