RETURN CHANNEL OF A MULTISTAGE TURBOCOMPRESSOR OR TURBOEXPANDER WITH ROUGH WALL SURFACES

摘要

A return stage of a radial turbo fluid energy machine, in particular of a radial turbo compressor, having an axis of rotation, the return stage has an annular flow channel for feeding a flowing process fluid from a flow opening of a first impeller to a flow opening of a second impeller arranged downstream. In order to increase efficiency, the flow channel is defined by bounding surface areas, of which at least one certain rough area extending in the circumferential direction has a surface roughness that is increased in relation to the her areas.