Abstract: Fluid pumping apparatus comprises(a) a housing,(b) an impeller rotatable in the housing to discharge fluid centrifugally outwardly,(c) a rotary spool having an inducer section through which intake fluid passes to the impeller,(d) a rotary diffuser associated with the rotary spool and having driving vanes located at the inlet of the diffuser and outwardly of the impeller periphery for rotatably driving the spool in response to outward flow of said discharged fluid against and between the vanes.

Abstract: A diffuser for use with a centrifugal compressor utilizes a symmetric arrangement of vanes which direct the gas flow along a plurality of passageways that are substantially tangential to the outer periphery of the impeller. Each vane making up the array is pivotally mounted near its opposite ends. Controls are provided so that rotation of the vane assembly about the innermost set of pivot points will vary the cross-sectional area of the ducts formed between adjacent vane members. This allows efficiency of the diffuser-compressor combination to be maximized for a multiplicity of speed and load conditions.