The invention relates to an assembly for a turbomachine extending along an axis (X) and comprising: —a ferrule (32) designed to define a fan duct (5) of a gas stream of the turbomachine, —a fan casing (2) radially surrounding the ferrule (32) and defining with the ferrule (32) the fan duct (5), —a rectifier (6) comprising a plurality of vanes (7) comprising a first vane (7a) and a second vane (7b) adjacent to the first vane (7a), the vanes defining between them a converging flow channel (13) designed to direct and accelerate the stream by means of an inlet section (14a) included in a plane non-perpendicular to the axis of the turbomachine and an outlet section included in a plane (14b) perpendicular to the axis (X) of the turbomachine, the first vane (7a) and the second vane (7b) each having an unducted downstream portion which forms a trailing edge.