Analysis of effect of impeller geometry including blade outlet angle on the performance of multi-pressure pumps: Simulation and experiment
In this paper, the effect of outlet angle geometry of the blades of the impeller of a multi-pressure pump on the pump’s head and efficiency using two approaches, namely numerical approach (Computational Fluid Dynamics) and experimentation are investigated. Herein, a closed single-suction, five-blade impeller with three different outlet angles (27°, 30°, and 33°) is analyzed. The impeller model was first built in SOLIDWORKS software before analyzing the fluid flow with the help of ANSYS Fluent software. All surfaces were meshed through irregular gridding. Considering high flow velocity along with low thickness of boundary layer near the blade tips, smaller mesh sizes were used across these areas. Blade surfaces were meshed using square elements. Furthermore, in order to model the volumes, irregular gridding and TGrid algorithm were undertaken. Generated with this algorithm are quadtrial elements of known size. In volumetric meshing stage, aspect ratio was set to a maximum of 0.6. In the experimentation phase of this research, a multi-stage pump was tested at 2000 rpm and 30 kW of input power with three impellers of different angles. At specific values of outlet angle and impeller outlet width, some reductions in hydraulic and mechanical losses within the impeller along with some rises in the pump head and efficiency were observed. Simulation results were found to be in good agreement with the experimental data; so as one can save time and money by using numerical simulation approaches in ANSYS Fluent rather than undertaking experimentations. Numerical and experimental analyses revealed that the maximum pump head and efficiency have been witnessed at the outlet angle of 30°. This is because of the reduced losses by water recirculation within the volute and outlet impellers.