No abstract

A study to investigate the influence of penstock outlet and the flat blade lateral twist angle on the performance of an existing Pico-hydro system was undertaken. Five penstock reduced from76.2 mm to 15, 17.5, 20, 22.5 and 25 mm diameters at the outlet and a runner with adjustable flat blades were fabricated from mild steel sheet. For each of the penstock outlets, five blade twist angles of 50, 55, 60, 75 and 90° were tested and the turbine and alternator speed measured with tachometer. The initial and final levels of water in the overhead tank as well as the periods of tests were also measured. The data collected was used to compute the flow rate and power for each set. A maximum computed power of 5600 W was obtained with the 25 mm penstock outlet in conjunction with the blade twist angle of 75 o. Also, the maximum speed 1180 rpm of the alternator shaft was obtained for a penstock outlet diameter of about 20.25 mm at the same twist angle of 75 o. These results imply that for the system potentially could generate appreciable power using flat blades with the penstock outlets and blade twist angles in the ranges > 20 mm and ≥ 60 0 respectively. Considering the simplicity of the flat blade configuration, the results indicate good promise for providing relatively cheap, clean and convenient domestic power with further work on the 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.

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.