Inlet guide vanes (turbo)

Inlet guide vanes are adjustable vanes ahead of the turbocharger compressor that pre-swirl the incoming air to change the effective mass flow and shift the operating point across the compressor map. Closing the vanes raises charge pressure at low engine load and widens the surge margin; opening them passes full flow at high load. Variable inlet guide vanes, paired with variable turbine area on the gas side, let one turbocharger match a wide load range without a cut-out, which supports part-load SFOC and Tier III exhaust gas recirculation operation. The mechanism is a ring of pivoting vanes driven by an actuator on the compressor inlet casing.