US Patent 8016557 Airfoil diffuser for a centrifugal compressor

An airfoil diffuser for a centrifugal compressor formed by a diffuser passage area and a plurality of diffuser blades located within the diffuser passage area. The diffuser passage area is defined between a hub plate and a shroud of the centrifugal compressor. Each of the diffuser blades has a twisted configuration in a stacking direction as taken between the hub plate and an outer portion of the shroud located opposite to the hub plate. As a result of the twisted configuration, the diffuser blade inlet blade angle decreases from the hub plate to the outer portion of the shroud and solidity measurements at leading edges of the diffuser plates vary between a lower solidity value measured at the hub plate of less than 1.0 and a high solidity value measured at the outer portion of the shroud of no less than 1.0.