Experimental investigations on pump running in turbine mode with different draft tubes

Abstract

In mini/micro hydro schemes, centrifugal pump can be used as hydraulic turbine in view of its similarity with Francis turbine and various advantages associated with pumps. At present, standards are not available for design of draft tube for pump as turbine (PAT). Hence, current trend is to use the standards available for hydraulic turbines. Improper selection of draft tube may lead to huge vibrations in system; which may affect life as well as overall performance of the system. Researchers have used either straight or diverging draft tube for PAT. It is required to access necessity of diverging draft tube for PAT in view of performance, life and cost involved with it. In this paper, performance of PAT studied with straight and diverging draft tubes in terms of operating characteristics and vibration analysis are presented. Analysis concluded that, PAT works more efficiently with diverging draft tube and subjected to lesser vibrations.