Influence of Liquid Viscosity on Performance and Flow Pattern for a Vortex Pump

The hydraulic performance and flow in 32WB8-12 standard motor-connected vortex pump with a specific speed of 76 are studied by using CFD approach under water and viscous oil flow conditions. The variations of performance curve, hydraulic loss and dimensionless liquid angular velocity in the chamber in front of the impeller caused from increasing liquid viscosity are clarified. The flow rate, head, efficiency and impeller disc friction loss correction factors are correlated to impeller Reynolds number at three working conditions, respectively. these factors are compared with those of centrifugal pump carefully. Against centrifugal pumps, the impeller disc friction loss is only 5% of the shaft-power in the vortex pump in maximum, suggesting the pump belongs to a type of pump with a lower impeller disc friction loss. Liquid viscosity can demonstrate less effect on both flow rate and efficiency correction factors but more substantial influence on head correction factor. If the impeller Reynolds number is not smaller than 1×10⁴, the vortex pump can maintain a better performance, and be able to transport more viscous liquids than water. There is a re-circulating vortex in the meridian plane of the chamber, and its position, size and mean liquid rotating angular velocity in the chamber depend on liquid viscosity.