A device for imparting a whirling motion on the flow of air for supplying a turbo-supercharged internal-combustion engine is designed to be interposed in the duct for supplying the air upstream of the supercharger for supercharging the engine. The device comprises an elbow-shaped portion of duct and partializing means, which are able to limit the section of passage in the upstream branch the aforesaid elbow portion to an area which constitutes a fraction of the total section of the duct and which is adjacent to a wall of the duct. In this way, the downstream branch of the elbow portion is reached by a tangential flow that gives rise to a helical flow of the air in said downstream branch. The device enables creation upstream of the supercharger of a negative pressure sufficient for enabling a recirculation of exhaust gases, upstream of the supercharger, and at the same time imparts on the air flow a whirling movement that enables the supercharger to be exploited in the most efficient way.