Centrifugal fluid machine

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.