A CFD parametric study of geometrical variations on the pressure pulsations and performance characteristics of a centrifugal pump

Pressure pulsations may be troublesome during the operation and performance of centrifugal pumps. Such pressure pulsations have traditionally been investigated experimentally but numerical analysis techniques allow these effects to be explored. The multi-block, structured grid CFD code TASCflow has been used to investigate the time variation of pressure within a complete double entry, double volute centrifugal pump. This investigation has taken the form of a parametric study covering four geometric parameters, namely the cutwater gap, vane arrangement, snubber gap and the sidewall clearance. Taguchi methods allowed the number of transient analyses to be limited to a total of 27. Three flow rates were investigated and the pulsations were extracted at 15 different locations covering important pump regions. Taguchi post-processing analysis tools were used to rank the relative importance of the four geometric parameters at each location for each flow rate. The cutwater gap and vane arrangement were found to exert the greatest influence across the various monitored locations and the flow range. A rationalisation process aimed at increased component life and reduced noise/vibration through reductions in pressure pulsations has produced geometric recommendations, which should be useful to designers.