Performance analysis of double suction centrifugal pumps with a novel impeller configuration

Pumps are largely used in domestic, civil, industrial and agricultural systems. It is estimated that they are responsible of about 10% of the world energy consumption. To favor sustainability and reduce carbon footprint of pumps, it is required to improve their efficiency. In recent years, the authors proposed a novel impeller configuration (cross-vaned, with a completely new design of the vanes) for double suction centrifugal pumps with higher efficiency and reduced blade loading compared to conventional back-to-back impellers. Given the good results, herein a second version of the prototype has been designed by means of a one-dimensional (1D) in-house code with the purpose to increase the blade loading by reducing the number of blades. The new 5-bladed crossed-vaned prototype was studied numerically, then constructed and experimentally tested showing a good agreement between numerics and experiments in terms of head coefficient and efficiency. Through numerical simulations, pressure, velocity and vorticity fields at the outlet of the impeller have been investigated; besides, a new slip factor correlation is proposed for this new generation of pumps. Moreover, the new configuration confirms its benefit in term of reduction of the slip factor and increase of the global efficiency, proving to be useful for retrofitting of old impellers, with a higher efficiency and smaller overall dimensions. Finally, an example of conventional impellers retrofitting in a real pumped-storage system is presented and its impact in terms of global efficiency and carbon footprint is discussed.