Experimental Investigation of the Influence of Penstock Configuration and Angle of Twist of Flat Blades on the Performance of a Simplified Pico-Hydro System

The effects of penstock configuration and lateral twist angle of the flat blades on the performance of a simplified Pico hydro system were examined as part of an ongoing development. Two configurations of the penstock having 2 and 1 stages of area reductions from 3 to 2 inches and 3 to 2 inches within the lower 1 m of their total height were used. Turbine runners with flat blades laterally twisted at angles of 30, 45, 60, 75 and 90° were fabricated locally and the system performance studied. The speed of rotation of the alternator and turbine shafts were measured and the available fluid power, flow rate and net head were computed. The results show that the 90° blade twist gave the best performance of the simplified system in terms of rotational speed and consequently power for both penstock configurations while the 30° twist yielded the least values of the parameters. However, the respective values for the 1st configuration were relatively higher for all the twist angles used. The maximum values of the parameters obtained for the 2-stage area reduction were 1844.7 rpm and 3636 W while the corresponding values for the other configuration were 1810.6 rpm and 2422 W The simplicity of the flat blade configuration coupled with the system performance for the entire blade twist angles indicates good promise for the implementation of the system for generation of clean, decentralized energy in line with current global trends even in locations without naturally flowing water.