Impeller Geometry Effects on Performance of Centrifugal Pump for Handling Viscous Fluids

Considering that centrifugal pump performance severely decreases in handling viscous fluids, so the reduction of performance is improved by variation in original geometry of centrifugal pump impeller. The present work is an attempt to simulate three-dimensional flow numerically from the centrifugal pump along with its volute, including original geometry and applied changes in geometry. The simulated centrifugal pump type is a 65-200, single axial suction and vane less volute casing, equipped with an impeller of 203 mm in outer diameter and 6 backwards curved blades. When the pump is running at 1450 rev/min and handling oil with 43Cst viscosity, the best efficiency point corresponds to 56 m3/h flow rate and 13.5 m height. A one dimensional theory model was established to identify such effect mathematically. The results showed that the blade exit angle is significant. The impeller with the exit angle of30 degree and the passage width of 21mm illustrated the best efficiency. Moreover, a one dimensional hydraulic model was proposed to investigate the effect of blade exit angle and passage width analytically at various operation conditions.. The numerical simulation was done for three different blade exit angles 27.5, 30 and 32.5 degree with two widths of impeller passage 17 and 21 mm. Finite volume method was used for discrediting governing equations and solving equation was derived by a high resolution algorithm. SST turbulence model was used here. Steady state simulation uses a Multi reference frame in which impeller is in rotational reference frame, and volute is in stationary reference frame and connects to each other by frozen rotor. Numerical results have been compared with experimental results and there was good agreement between these results. It can be seen that at blade exit angle 30 degree and 21 mm of passage width, head and efficiency increase in modified geometry of pump that and this is due to decreasing the dissipations arising by vortex formation in impeller passage

کلیدواژه ها:

centrifugal pump ، viscous fluid ، outletangle ، passage width ، performance ، simulation ، turbulence ، SST