Compressor including aerodynamic swirl between inlet guide vanes and impeller blades

A compressor, comprising:

• an inlet defining an intake passage;
• a plurality of inlet guide vanes within the intake passage, fluid flow through the plurality of inlet guide vanes into the intake passage being selectively adjustable to control fluid flow through at least a portion of the intake passage downstream of the plurality of inlet guide vanes;
• an impeller including a plurality of blades, the impeller directing fluid from the intake passage toward an outlet;
• and
• a plurality of swirl nozzles having outlets positioned downstream of the plurality of inlet guide vanes and upstream of the impeller, the plurality of swirl nozzles being configured to introduce fluid into the intake passage to cause swirl of fluid in the intake passage between the plurality of inlet guide vanes and the impeller,
• wherein
• the impeller includes a hub at a center of the blades,
• the impeller includes a shroud near radially outer ends of the blades,
• the leading edges of the blades have a length between the hub and the shroud,
• the swirl of fluid in the intake passage caused by the plurality of swirl nozzles establishes a varying incidence angle of fluid encountering the impeller blades along at least leading edges of the blades,
• the established varying incidence angle achieves a selected compressor efficiency,
• the established varying incidence angle varies along substantially an entire length of the leading edges of the blades, and
• the incidence angle is different for different portions of the leading edges.