A diffuser for a centrifugal compressor has diffusing passages of circular or oval cross section which converge toward a throat and then diverge. The passages are of generally spiral curvature, at least in the converging portion. The entrances of the diffuser passages merge to define leading edges of generally elliptical shape between the passages.
This invention is proposed as an aerodynamically more efficient vaned diffuser for centrifugal compressors than heretofore achieved, while still respecting the usual diffuser requirement of a limited overall diameter. The invention is so to shape the early entering portion of the diffuser side-walls and the vanes as to achieve for the first time, isobars across the so-called throat which are highly oblique to the flow direction there, instead of heretofore always an isobar which is very nearly normal or normal across the passage at that throat. This is more understandably but still briefly explained in the two sections following, on Background, and Summary, of the Invention.
A centrifugal compressor including a one-piece diffuser ring having a circumferentially extending vaneless diffuser space for receiving compressed gas exiting the compressor impeller, and for guiding the compressed gas to a plurality of outwardly extending and circumferentially arranged diffuser channels each of generally circular cross-section.
A radial flow compressor is described which includes a diffuser having an annular entrance chamber surrounding the circumferential discharge of the impeller of the compressor. Diffuser channels extend from this annular chamber to an axial flow diffuser from which the compressed air is discharged into a collection chamber. The annular chamber is provided with contoured nodes from which the channel diffusers respectively extend at relatively low angles, tangentially in relation to the periphery of the impeller.
A supersonic shock wave compressor diffuser forms a concentric annulus about a radial compressor having a central axis. Circular channels diverge with an increasing divergence angle as they extend along an arcuate longitudinal center line from an inner circumference very near the periphery of the compressor to the outer circumference of the diffuser. Shock waves may occur within the channels near the inner circumference of the diffuser or may occur within a vaneless diffusion space adjacent the periphery of the compressor and provide efficient energy conversion and reduce the velocity substantially below MACH 1 to further improve the efficiency of the subsonic diffusion downstream therefrom. A logarithmic spiral is approximated by a circular arc subtended by the channel longitudinal axes to permit recovery of angular momentum while the circular cross section of the channels permits recovery of swirl velocity energy. The required diameter of the outer circumference of the diffuser is reduced by using the shock waves to greatly reduce gas velocity within a short distance, by the curvature of the channels and by the angle of incidence of the longitudinal channel axes.
