Experimental study of a centrifugal pump operating as a hydraulic turbine

An experimental investigation of centrifugal pump has been carried out to study its characteristics in pump and turbine mode operation (PAT). The correlation between pump and PAT performance is a major problem. Several methods have been developed to predict the best efficiency of pumps running as turbines, but their results are not in good coincidence with experimental data for all pumps. Fluid dynamic behavior of PAT changes appreciably, in relation to its localized and distributed hydraulic losses, velocity profiles and pressures at homologous points. It is not possible to infer the behavior of a PAT using similarity parameters from pump mode performance; very large errors are made. This paper presents the experimental parameters of the operating of a PAT with specific number low. In order to determine the pump’s characteristic as turbine, we used a closed-circuit experimental setup in which the admission pressure head was realized with another pump and the correlation between the diameter of the PAT and the specific number for three different ranges of flow was determined. This is based on an experimental database on a centrifugal pump of specific number 17 .80 [RPM, m3 /s, m] in bothrotation modes and for a speed range of rotation between 250 and 2500 RPM. All required parameters were measured to achieve complete characteristic curves of the reverse pump. The functional characterization showed curves of the hydraulic machine in the turbine mode with variation of operating parameters, such as rotation speeds, heights, and flow rates. With the results obtained, the comparatives made allowed observing the influence of these variations on the performance of the PATs. Curves obtained allowed inferring the behavior in turbine mode from pump mode parameters. Values obtained from the derived correlations showed good match with experimental results.