MODEL TESTING OF SINGLE- AND THREE-STAGE MODIFIED SAVONIUS ROTORS AND VIABILITY STUDY OF MODIFIED SAVONIUS PUMP ROTOR SYSTEMS

Abstract

The suitability of modified Savonius wind rotors for water-pumping application is studied with a mathematical model developed for estimating the discharge over a period of time. Single- and three-stage modified Savonius rotors, which are extensively tested in an open jet wind tunnel, are chosen. The best geometrical configuration for a single-stage rotor has shown a maximum coefficient of power of 19% at a Reynolds number of 120000, which increases with the increase in the Reynolds number. The coefficient of power at a higher Reynolds number experienced in the field trials is estimated by extrapolating the results at a lower Reynolds number. The discharge for these modified Savonius rotors is estimated from the mathematical models developed for roto-dynamic and piston pumps at design wind velocities of 6 and 8.5 m/sec. The estimated discharges for a single-stage rotor of 3 m diameter at design wind velocities of 6 and 8.5 m/sec are 5000 and 6000 m(3)/month for roto-dynamic pumps. The estimated discharge is substantially higher for roto-dynamic pumps than for piston pumps.