Optimised Design. The performance comparison of the optimized designs selected from the optimisation process with baseline design in pump mode is presented below, in Figure 5. The designs shown as DP105, DP106, DP107 and DP108 represent designs obtained from the optimisation process. The average stage efficiency between the 3 operating points improved by up to 2.6% points for the best performing candidate. As a result of the power minimization objective, the power is dropped considerably for the optimized designs compared to the scaled baseline (Section 3. Scaling to model scale) at lower flow rates. The minimum head requirement of 7 [m] is met at the 120% flow rate by all the designs. NPSHr values computed also showed improvements over the baseline.
a) Stage Head b) Stage Efficiency c) Stage Power Figure 5 : Comparison of the Optimised Designs versus the baseline design - Pump Mode The performance comparison in turbine mode is presented below in Figure 6. The average stage efficiency between the 3 operating points improved by up to 1.1% points for the best performing candidate. As a result of the power maximization objective, the power is increased considerably for optimized designs compared to the baseline. Though the total head remained the same, the increased flow rate helped in increasing the power output.
a) Volume flow rate b) Stage Efficiency c) Stage Power
