The invention relates to a mixing device and a turbofan engine having such a mixing device 30 for mixing a first gas flow 40 with a second gas flow 50 in a turbofan engine 20, having an actuating device 95 and walls 60, which bound a channel 65 for the first gas flow 40 and a channel 70 lying radially outside for the second gas flow 50, the actuating device 95 comprising a coupling element 110 that is coupled to the walls (60), the actuating device 95 being designed to pivot the walls 60 between a first position and a second position disposed radially outside relative to the first position, the actuating device 95 comprising an adjusting ring 105 that can be rotated between a first rotating position and a second rotating position in the peripheral direction and that is joined to the coupling element 110.