Experimental and Numerical Evaluation of the NPSHR Curve of an Industrial Centrifugal Pump

Cavitation triggers harmful flow instabilities yielding both significant decrease of performance and reduced reliability. The aim of this paper is to investigate the accuracy of numerical methodologies for the correct prediction of cavitation inception in centrifugal pumps. Preliminary analyses are performed on the NACA 0009 hydrofoil using the ANSYS CFX V14.5 code. The available bubble dynamics model is calibrated using the experimental data in cavitation conditions. Then, the optimized parameters are used for the evaluation of the NPSHR curve of the R250 centrifugal pump industrial pump designed by WEIRGabbioneta srl. Reynolds-Averaged Navier-Stokes mono- and two-phase calculations are performed. The performance curve of the R250 centrifugal pump is evaluated at first, and then the NPSHR curve is obtained for the design flow rate. The control volume of the numerical analysis includes all the hydraulic features from flange to flange (except for the side chambers) and then a direct comparison with the available experimental data obtained during two experimental campaigns is possible. The numerical activity demonstrated that an adequately calibrated model is able to reproduce the shape of the cavitation curve of an industrial centrifugal pump, although the NPSHR value is underestimated.