Abstract: The invention relates to a burner comprising several substantially concentric channels, one (1) of which is arranged outside of all fuel supply conduits and is delimited by two pipes (2,3), whose axes (4) are placed in a parallel position and which are movable with respect to each other. According to said invention, diverting members (6) used for imparting a tangential component (7) to a fluid flowing in the channel (1) are carried by the first pipe (2) and are fixed thereto, the second pipe (3) comprises a drive portion (9) for driving the fluid outside the diverting members (6) and the angle of tangential deviation of the fluid at the downstream end (8) of the channel (1) depends on the axial position of the second pipe (3) with respect to the first pipe (2).