Centrifugal compressor diffuser and centrifugal compressor provided with the same

A centrifugal compressor diffuser comprising:

• a shroud-side wall provided downstream of a centrifugal impeller;
• a hub-side wall provided so as to face the shroud-side wall;
• a plurality of shroud-side blades fixed at base ends thereof to the shroud-side wall;
• and
• a plurality of hub-side blades fixed at base ends thereof to the hub-side wall, wherein
• the shroud-side blades are thick blades having a wedge shape or a channel shape gradually widening from leading edges toward trailing edges of the shroud-side blades in cross-section in a direction perpendicular to a blade height direction,
• the hub-side blades are thin blades, and
• the hub-side blades and the shroud-side blades to be combined with the hub-side blades are combined in such a state that inlet angles thereof differ from one another and that top ends, in a blade height direction, of the shroud-side blades to be combined with the hub-side blades overlap one another over the entire blade lengths of the hub-side blades.

A centrifugal compressor diffuser comprising:

• a shroud-side wall provided downstream of a centrifugal impeller;
• a hub-side wall provided so as to face the shroud-side wall;
• a plurality of shroud-side blades fixed at base ends thereof to the shroud-side wall;
• and
• a plurality of hub-side blades fixed at base ends thereof to the hub-side wall, wherein
• the hub-side blades and the shroud-side blades to be combined with the hub-side blades are combined such that their inlet angles differ from one another,
• side portions, on the side of the shroud-side blades, of the top ends, in the blade height direction, of the hub-side blades and side portions, on the side of the hub-side blades, of the top ends, in the blade height direction, of the shroud-side blades form overlapping portions extending over the blade length of the hub-side blades, and
• side portions, opposite to the side of the shroud-side blades, of the top ends, in the blade height direction, of the hub-side blades are separated from the overlapping portions.