ABSTRACT
The effects of penstock area reduction and number of turbine v-blades on the performance of a simplified Pico-hydro system which is currently undergoing development was investigated in this study. One and two stage area reductions from 3-2½ inches and then from 3-2½-2 inches were effected on the penstock, and turbine runners with 6 to 12 v-blades were tested for each configuration. The turbine and alternator shaft speeds as well as the depth of water in the overhead and underground reservoirs were monitored. The gross head, volumetric flow rates for each operation, fluid power and the head losses involved were computed. The results obtained indicated that the two stage area reduction of the penstock with the runners having 9 -10 blades produced the highest shaft rotational speeds as well as computed fluid power. The differences between the results for the two penstock configurations were however not statistically significant at 95% level while those between the different number blades were highly significant at the same level. This implies the existence of the possibility that further stages of reduction in the penstock area could improve the system performance while no advantage exists for system performance in its present state for number of blades lower than or beyond 9 to 10. This is useful for the further development of this simple decentralized and environmentally friendly system for end user implementation.
