Centrifugal fluid machine

Abstract

A centrifugal compressor includes an impeller and a diffuser arranged around the outer periphery of the impeller and including a pair of annular, spaced diffuser plates defining a diffuser channel therebetween. A plurality of guide vanes are provided on at least one of the pair of diffuser plates to guide a low flow angle portion of a fluid flow introduced into the diffuser channel from the outlet of the impeller. The guide vanes each extend from the inlet of the diffuser channel to a position which does not exceed about one half the distance between the inlet and the outlet of the diffuser channel and have a height which is less than one half the spacing between the pair of diffuser plates.

What is claimed is: 
     
       1. A centrifugal fluid machine comprising: an impeller having an outlet;   a diffuser having performance characteristics of the vaneless diffuser type located around the outlet of said impeller and including a pair of opposed, but spaced annular diffuser plates having respective inner surfaces which define a diffuser channel therebetween, said diffuser channel having an inlet continuous to the outlet of said impeller and an outlet radially remote therefrom; and   a plurality of guide vane means, provided in a circular array on at least one of said inner surfaces of said pair of diffuser plates in a manner extending from a position within the inlet of said diffuser channel contiguous with the outlet of the impeller toward the outlet of said diffuser channel to a position which does not exceed about one-half the distance between said inlet and outlet of the diffuser channel in a region of a low flow angle portion of fluid flow introduced into the diffuser channel from the impeller outlet by said impeller, for guiding only said low flow angle portion of the fluid flow from the outlet of the impeller, said guide vane means each having a height, corresponding substantially to that of the low flow angle flow region, 1/2 to 1/5 the spacing between said pair of diffuser plates.   
     
     
       2. A centrifugal fluid machine as claimed in claim 1, wherein said impeller includes a shroud, a hub and a plurality of blades extending between said shroud and said hub, wherein said pair of diffuser plates are respectively disposed with one on the side of the shroud and one on the side of the hub, and wherein said guide vanes means are provided on the one of said pair of diffuser plates which is disposed on the side of said shroud. 
     
     
       3. A centrifugal fluid machine as claimed in claim 1, wherein said guide vanes are provided on each of said pair of diffuser plates. 
     
     
       4. A centrifugal fluid machine as claimed in claim 1 or 2 or 3, wherein said guide vane means comprise guide vanes which each have a uniform height along its entire length. .Iadd. 
     
     
       5.  A centrifugal fluid machine comprising: an impeller having a shroud, a hub and a plurality of blades extending between said shroud and said hub, said shroud and said hub having their respective adjacent radially outer edges cooperating with each other to define therebetween an outlet;   a vaneless diffuser located around the outlet of said impeller and including a pair of opposed, but spaced first and second annular diffuser plates respectively located adjacent to said shroud and said hub, said first and second diffuser plates having respective inner surfaces which cooperate with each other to define therebetween a diffuser channel, said diffuser channel having an inlet continuous to the outlet of said impeller and an outlet radially remote therefrom, and   a plurality of guide vanes, provided in a circular array on the inner surface of at least one of said first and second diffuser plates, for rectifying distorted flow from the outlet of said impeller, said guide vanes extending in said diffuser channel from close to the outlet of the impeller toward the outlet of said diffuser channel, said guide vanes extending from the inner surface of said at least one diffuser plate toward the other diffuser plate to a location substantially equal to the value of the small flow angles widthwise of the inlet of said diffuser channel. .Iaddend. .Iadd.   
     
     
       6.  A centrifugal fluid machine as defined in claim 5, wherein said location to which said guide vanes extend from the inner surface of said at least one diffuser plate toward the other diffuser plate is positioned within a range from 1/2 to 1/5 the width of said diffuser channel. .Iaddend. .Iadd.7. A centrifugal fluid machine as defined in claim 5, wherein said guide vanes extend from the inner surface of said first diffuser plate toward said second diffuser plate. .Iaddend. .Iadd.8. A centrifugal fluid machine as defined in claim 5, wherein said guide vanes extend from the inner surface of said second diffuser plate toward said first diffuser plate. .Iaddend. .Iadd.9. A centrifugal fluid machine as defined in claim 5, wherein said guide vanes extend from the inner surface of each of said diffuser plates. .Iaddend. .Iadd.10. A centrifugal fluid machine as defined in claim 5, wherein said location of the guide vanes substantially corresponds to a point at which one of actual values of flow angle widthwise of the inlet of said diffuser channel is coincident with a value of a mean flow angle of said actual values at the side of said at least one diffuser plate. .Iaddend. .Iadd.11. A centrifugal fluid machine as defined in claim 5, wherein said guide vanes extend in said diffuser channel from a location coincident with the inlet of said diffuser channel. .Iaddend.