Inlet swirl control for turbochargers

A compressor inlet duct for directing an inlet flow into an inlet compressor of a turbocharger, the inlet compressor coupled in an internal combustion engine, the inlet duct comprising:

• one or more relief features disposed on an inner surface of the inlet duct, the one or more relief features protruding into the inlet flow to cause the inlet flow to swirl in a first direction before reaching the inlet compressor, the first direction being a same direction as a direction of spin of the inlet compressor, the one or more relief features including three elongate ridges, the three elongate ridges being respectively substantially equally spaced on the inner surface, spaced apart from one another on the inner surface, and not continuous with one another around a circumference of the inner surface or along a central axis of the inlet duct, each ridge of the three elongate ridges extending around only a portion of the circumference of the inner surface, where a most upstream first ridge and a most downstream third ridge of the three elongate ridges do not overlap one another along the central axis of the inlet duct, where the three elongate ridges are formed integral with the inlet duct, and where a relief feature wall thickness of the three elongate ridges is equal to an inlet duct wall thickness of the inlet duct.

A system, comprising:

• an inlet duct of an inlet compressor directing an inlet flow into the inlet compressor of a turbocharger of a direct-injected engine;
• and
• one or more relief features including only three elongate ridges disposed on an inner surface of the inlet duct and spaced apart from one another along a central axis of the inlet duct, the three elongate ridges protruding into the inlet flow to cause the inlet flow to swirl in a first direction before reaching the inlet compressor, the first direction being a same direction as a direction of spin of the inlet compressor, the three elongate ridges formed integral with the inlet duct, each ridge of the three elongate ridges extending around only a portion of a circumference of the inner surface, where a most upstream first ridge and a most downstream third ridge of the three elongate ridges do not overlap one another along a central axis of the inlet duct, and where a diameter of a first portion of the inlet duct arranged upstream of a second portion of the inlet duct including the three elongate ridges is equal to a diameter of the second portion of the inlet duct.