Various embodiments of the invention relate to an intake channel of an internal combustion engine in which an adjustable position guide vane is configured to modify the velocity distribution inside the intake channel in order to vary the mean swirl number generated by the channel. The intake channel may comprise a combination of two or more ports, which can be helical or tangential, depending on their shape. By varying the velocity distribution inside the intake channel it is possible to vary the mean swirl number in an internal combustion engine. Contrary to existing systems to vary the swirl in internal combustion engines, the invention proposed does not require the separation of both ports inside the intake channel by a wall in order to achieve a variation in the swirl.