A standard volute-type, radial-flow, centrifugal pump was instrumented to obtain the pressure distribution in the volute and also the bearing reactions from the pump hydraulic force transmitted to the shaft. The resultant force from the integrated pressure distribution was found to give a reasonable design approximation of the radial force. An analysis of hydraulic conditions within the volute gave pressure distributions and radial-force magnitudes that were comparable to those measured with certain qualitative interpretations about internal recirculations. In addition, the pressure-distribution analysis furnished an interpretation of the effect of the volute on the pump head-capacity performance with corrections to the impeller head. The predicted head-capacity relationship had the form of the measured pump performance.

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Three diffuser sets (N/W1, held constant in each set) were built and tested for performance and flow regime over a range of total area ratios, AR, which yielded unstalled and stalled flows. At each AR and N/W1, a simple class of convex-inward (trumpet-shaped), straight, and convex-outward (bell-shaped) wall shapes were tested. It is concluded that there is little advantage to be gained by contouring the walls of two-dimensional diffusers. A corollary result shows that the performance prediction method of reference [1] gives good results for unstalled diffusers.

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volute results from a mechanical-energy balance on an element of the volute as in Fig. 10. For the element, the mechanicalenergy rate loss is the difference between the energy-rate input and the energy-rate output, or, dEm = 0 P + P tM('