Characteristic Curve Prediction of a Commercial Centrifugal Pump Operating as a Turbine Through Numerical Simulations

In this work, we seek to predict the characteristic curve of a commercial centrifugal radial flow pump operating as a turbine, applying a novel methodology based on the state of the art. Initially, the characteristic curve in pump mode is validated through numerical simulations. The results obtained are approximate to the points awarded by the manufacturer, with an error of less than 7% at the best efficiency point. Subsequently, the characteristic curve is generated in turbine mode, obtaining an error of less than 10% respect to mathematical model. Then, velocity and pressure contours are evaluated to validate the fluid dynamic behavior. Finally, the site operating conditions for electricity generation are obtained. With this, it is proposing a methodology for the selection of these turbomachines, applying an economic technology for zones that do not have access to the electrical energy, since it was not found a method that is being applied for its correct election in the hydroelectric generation at low scale.

Overall Performance of a Centrifugal Vaned Diffuser Pump for Different Flow Rates, Experimental and Numerical Comparisons

The article presents the analysis of the interactions between the impeller and the vaned diffuser of a radial flow pump. The tests were carried out on the so-called SHF impeller, coupled with a vaned diffuser, and working with air. The particularity of this machine is that the diffuser design flow rate corresponds to 80% of the impeller one. All experimental works were performed at the Fluid Mechanics Laboratory in ENSAM, Lille, France. Investigations have been made for five different flow rates. Global performances of the machine are evaluated thanks to pressure measurements and averaged velocities obtain with a three hole probe, at nine angular positions at diffuser inlet and outlet just as five radial positions in a middle section of a blade-to-blade passage. A post-processing procedure, based on statistical tools, was applied to the experimental results in order to reach a better understanding of the phenomena. In another approach, a numerical simulation of the flow inside the pump, for eight different relative angular positions of the diffuser relative to the impeller (Frozen rotor) was performed by the STAR-CCM+ software. The experimental results were compared to numerical data obtained with the help of STAR-CCM+ computer code.