CFD Analysis of Pump Performance with Fluids Having Different Viscosity at Different Exit Blade Angles

The objective of this paper is to study the effect of the exit blade angle on the performance of a centrifugal pump when the pump handles fluids of varying viscosity. To achieve the said objective, one radial centrifugal pump was selected. The pump has to supply the fluid at the head of 40 m having a flow rate of 288 cum/h. The speed is 1,450 rpm. The data required by the software for model generation are calculated manually using the method suggested by Stepanoff. A model is prepared in ANSYS for exit blade angles of 24.5°, 26°, 28°, 29.5° and 31°. The said models of different blade angles are simulated in ANSYS at various operating conditions. For each exit blade angle, the fluid of different viscosity is taken to study its effect on pump performance. The fluids taken are water, castor oil, engine oil and methanol. It is found that as the exit blade angle increases, the performance of the pump improves. Also as the viscosity of the fluids increases, the efficiency decreases and the power consumption increases. It is found that as the pump handles high viscous fluids then the Best Efficiency Point (BEP) is obtained at a higher exit blade angle, because as the exit blade angle increases, the wake/turbulence at the exit of the impeller decreases.