To check that the measurements could be reproduced, each test was replicated three times (Rep.1, Rep.2 and Rep.3, respectively). Figure 6 shows a sample plot of the head, power input and efficiency as a function of the water discharge rate for the three replications, with pumping at a speed of 2900 rpm; the figure indicates that the function was replicable.
All data of each three replicates were averaged and plotted (Figure 7). The best results were obtained with a polynomial fitting of degree 2 for the head with respect to discharge (R2 = 0.998), a polynomial fitting of degree 3 for the