Computational turbulent flow characteristics in a centrifugal pump

Abstract

This investigation provides the 3D numerical simulations of a six-blade centrifugal pump that is commonly applied in agriculture and food processing sectors. The simulations were carried out using the unsteady Reynolds averaged Navier–Stokes equations. The k-omega turbulence model was used as a closure for the equations. The velocity and pressure flow fields were used to predict the turbulent flows in the pump under three different operating conditions (part-load 0.8Qd, design 1.0 Qd, and overload 1.2 Qd). The omega vortex identification criterion was further applied to visualize the coherent vortex structures in the impeller and volute at the investigated flow conditions. The impeller eye was characterized with the lowest static pressure fields causing this region to be highly susceptible to cavitation under all flow conditions. At the design point, the velocity vectors were orderly patterned along the blade flow curvature. However, flow separation occurred around the leading edge mainly due to the fact that the flow is non-tangential to the leading edge of the blade as a result of the unsteady effect developed upstream. In conclusion, it can be confirmed that the volute geometry is highly sensitive to the evolution and formation of vortices as revealed by the omega vortex criterion. This work reveals that the design of the volute geometry should be further improved to mitigate unsteady flow losses. Again, this kind of study helps reduce the required experimental measurements for the improvement and design of hydraulic machines.