Device for controlling a gas flow, an exhaust aftertreatment system and a system for propelling a vehicle

A device for controlling a gas flow through a passage, wherein the device comprises a plurality of pivotable gas flow control vanes, wherein the pivot axes of a first and a second adjacent vane are spaced so that a trailing edge of the first vane overlaps a leading edge of the second vane when the first and second adjacent vanes are positioned in a first mutual end state for substantially restricting the gas flow through the passage, wherein the second vane comprises a recess with such a shape that the trailing edge of the first vane is at least partly received in the recess when the first and second adjacent varies are positioned in the first mutual end state, wherein the ress of the second vane and the trailing edge of the first vane are configured for establishing a substantially constant, non-zero gap between opposite facing surfaces of the vanes when the first and second vanes are positioned in the first mutual end state, such that there is no contact between the recess of the second vane and the trailing edge of the first vane in the first mutual end state.