초록

A centrifugal compressor includes an impeller and a diffuser, the diffuser having a plurality of descrete D-shaped passages intersecting each other.

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The invention claimed is: 1. A centrifugal compressor comprising: an impeller having a hub mounted for rotation about a compressor central axis within an outer shroud, the impeller having an impeller exit; and a diffuser mounted downstream of the impeller exit, the diffuser having a plurality of ci

The invention claimed is: 1. A centrifugal compressor comprising: an impeller having a hub mounted for rotation about a compressor central axis within an outer shroud, the impeller having an impeller exit; and a diffuser mounted downstream of the impeller exit, the diffuser having a plurality of circumferentially-spaced discrete passages at least partially defining fluid paths therethrough, each path having an inlet and an outlet, the discrete passages being angled relative to one another such that adjacent discrete passages intersect each other to form an annular semi-vaneless diffuser inlet space upstream of the fluid path inlets, each discrete passage having a substantially D-shaped cross-section extending between said inlet and said outlet, the D-shaped cross-section being composed of a U-shaped arcuate surface opposing a substantially flat surface, the substantially flat surface being adjacent to the hub of the impeller and extending substantially radially from the hub at an inlet of each said passage, the U-shaped arcuate surface being adjacent to the outer shroud of the impeller at the inlet of the passage and facing axially rearward towards the substantially flat surface, the intersection of adjacent D-shaped passages in the semi-vaneless space forming partial vanes on the shroud side of the diffuser by the intersection of the arcuate portions of the passages, and wherein the intersection of the discrete passages creates a leading edge having a repeated pattern of swept back portions, each portion having an S-shaped double curve comprising opposing convex and concave curved ends and a substantially straight central edge portion. 2. The centrifugal compressor as defined in claim 1, wherein the partial vanes extend from the impeller exit to the fluid path inlets. 3. The centrifugal compressor as defined in claim 1, wherein the partial vanes are substantially tangential to an impeller circumference at the impeller exit. 4. The centrifugal compressor as defined in claim 1, wherein each of the partial vanes has a height, the height varying from a minimum adjacent the impeller exit to a maximum adjacent the fluid path inlet. 5. The centrifugal compressor as defined in claim 1, wherein the discrete passages are angled at their inlets relative to a compressor radial direction such that a central axis of each discrete passage is substantially tangential to a common circle formed about the compressor central axis. 6. The centrifugal compressor as defined in claim 1, wherein adjacent partial vanes define therebetween generally wedge shape passages adapted to guide air into the fluid paths. 7. A centrifugal compressor comprising: an impeller having a hub mounted for rotation about a compressor central axis within an outer shroud; and a diffuser mounted downstream from the impeller, the diffuser having a plurality of circumferentially-spaced discrete passages having a D-shaped cross-section, the D-shaped cross-section defined by an arcuate surface adjacent a shroud side of the diffuser and a substantially flat surface disposed adjacent a hub side of the diffuser, the adjacent discrete passages intersecting each other at their respective inlets to form leading edges of the passages, the leading edge of each passage being swept back and having a slightly S-shaped double curve comprising opposing convex and concave curved ends and a relatively straight central edge portion. 8. The centrifugal compressor as defined in claim 7, wherein the discrete passages are angled at their inlets relative to a compressor radial direction such that a central axis of each discrete passage is substantially tangential to a common circle formed about the compressor central axis. 9. The centrifugal compressor as defined in claim 8, wherein the leading edge generally defines a leading edge circle which is concentric with the common circle and radially outward from the common circle. 10. A centrifugal compressor comprising: an impeller having a hub mounted for rotation about a compressor central axis within an outer shroud; and a diffuser mounted downstream of the impeller, the diffuser having a plurality of circumferentially spaced discrete passages at least partially defining fluid paths through the diffuser each having an inlet and an outlet, the passages shaped with a substantially D-shaped cross-section having an arcuate surface opposing a substantially flat surface, the arcuate surface disposed adjacent a shroud side of the diffuser and the substantially flat surface disposed adjacent a hub side of the diffuser, the substantially flat surface being a surface of revolution formed about the compressor central axis of the impeller at an upstream end of the discrete passages, the arcuate surface and substantially flat surface being connected by two generally flat sides which smoothly blend into the arcuate surface, the discrete passages being angled relative to one another such that adjacent discrete passages intersect each other to form an annular semi-vaneless diffuser inlet space and defining leading edges of the discrete passages, the leading edge of each said discrete passage being swept back and having a slightly S-shaped double curve comprising opposing convex and concave curved ends and a relatively straight central edge portion. 11. The centrifugal compressor as defined in claim 10, the semi-vaneless space includes a plurality of partial vanes formed on the outer shroud by intersection of the arcuate portions of adjacent D-shaped passages. 12. The centrifugal compressor as defined in claim 11, wherein the partial vanes extend forwardly towards an exit of the impeller, and the partial vanes have a height which decreases towards the impeller exit. 13. The centrifugal compressor as defined in claim 11, wherein the partial vanes extend forwardly to an exit of the impeller, and are substantially tangential to an impeller circumference at the impeller exit. 14. The centrifugal compressor as defined in claim 10, wherein adjacent partial vanes define therebetween generally wedge shape passages adapted to guide air into the discrete passages.