Apparatus for conditioning an air flow through a nozzle

A nozzle (48) has a jacket (52) forms a channel (56). A domed annular guide element (58) which is separately arranged from one end (60) of the shroud (52) extends from a point (62) radially inwardly of the end (60) of the sheath (52) to a point (64) radially outside the end (60) of the sheath (52). The domed annular guide element (58) forms a first air stream (66) between the curved annular guide element (58) and the end (60) of the casing (52) and a second air stream (68) radially inward of the curved annular baffle (58).