Abstract: A turbocharger includes an acoustic damper for attenuating noise from the compressor. The damper includes inner and outer duct walls defining an annular cavity therebetween, the outer duct being longer than the inner duct. An upstream wall bounds the annular cavity at the upstream end and defines an inlet aperture for fluid to pass through into the inner duct, and a downstream wall is axially spaced from the downstream end of the inner duct so as to define an expansion chamber fluidly connected to the annular cavity. The downstream wall defines an outlet aperture for the fluid. Partition walls between the two ducts partition the annular cavity into at least a first Helmholtz resonator and a first quarter-wave resonator that are axially serially arranged, and a second quarter-wave resonator that is circumferential serially arranged with respect to the first Helmholtz resonator.

Abstract: A turbocharger includes an acoustic damper for attenuating noise from the compressor. The damper includes inner and outer duct walls defining an annular cavity therebetween, the outer duct being longer than the inner duct. An upstream wall bounds the annular cavity at the upstream end and defines an inlet aperture for fluid to pass through into the inner duct, and a downstream wall is axially spaced from the downstream end of the inner duct so as to define an expansion chamber fluidly connected to the annular cavity. The downstream wall defines an outlet aperture for the fluid. Partition walls between the two ducts partition the annular cavity into at least a first Helmholtz resonator and a first quarter-wave resonator that are axially serially arranged, and a second quarter-wave resonator that is circumferential serially arranged with respect to the first Helmholtz resonator.

Abstract: A compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the air inlet, the blades being movable radially inwardly from an annular space of the air inlet wall, into the air inlet, so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. A noise-attenuator is disposed in the annular space, downstream of the inlet-adjustment mechanism, for attenuating aerodynamic noise induced by the inlet-adjustment mechanism when it is closed.

Abstract: A compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the air inlet, the blades being movable radially inwardly from an annular space of the air inlet wall, into the air inlet, so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. A noise-attenuator is disposed in the annular space, downstream of the inlet-adjustment mechanism, for attenuating aerodynamic noise induced by the inlet-adjustment mechanism when it is closed.