A forage harvester configured for chopping harvested crops and producing a stream of chopped crop material. The harvester includes a rotatable blower drum mounted in a blower housing, for propelling the stream of crop material into an outlet duct of the harvester. The blower drum has an open structure which allows a flow of air in the axial direction of the drum. The blower drum is mounted between two sidewalls of the blower housing, at least one of the sidewalls comprising one or more air inlet openings. The harvester further includes at least one set of axial flow turbine blades, mounted between the blower drum and one or both of the sidewalls of the blower housing, the blades being rotatable about the blower drum's rotation axis.
