Inlet Swirl Control for Turbochargers

An inlet duct for directing an inlet flow into an 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 before reaching the inlet compressor;
• and
• guide vanes extending from the inner surface of the inlet duct, wherein the guide vanes protrude only partway toward a central axis of the inlet duct to leave an unobstructed central area in the inlet duct.

An inlet duct for directing an inlet flow into an inlet compressor coupled in an internal combustion engine, comprising:

• three elongate ridges disposed on an inner surface of the inlet duct and formed from three corresponding troughs disposed on an outer surface of the inlet duct, the three elongate ridges protruding into the inlet flow to cause the inlet flow to swirl before reaching the inlet compressor.

An inlet duct for directing an inlet flow into an 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 before reaching the inlet compressor, wherein the inlet compressor spins in a first direction, and wherein the relief features are elongate ridges that extend in a spiral fashion along the inner surface of the inlet duct, the elongate ridges having a circumferential component and a longitudinal component wherein the circumferential component is in the first direction, and wherein the relief features cause the inlet flow to swirl in the first direction.