US Patent 10502232 Turbocharger compressor having adjustable trim mechanism including swirl inducers

A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the compressor air inlet and located within an annular space within the air inlet wall. The blades are pivotable about respective pivot points such that the blades extend radially inward from the annular space into the air inlet when the blades are in the closed position so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. Upstream surfaces of the blades include swirl inducers that are structured and arranged to impart either pre-swirl or counter-swirl to the air passing through the orifice into the compressor wheel.