Effect of slope and number of blades on Archimedes screw generator power output

Abstract

A computational fluid dynamic (CFD) simulation of an Archimedes screw generator (ASG) was carried out in conjunction with laboratory-scale experiments to determine the effect of inclination angle and number of blades on ASG power production and performance. Good agreement was found between the model and experiment; the CFD model had relative errors in hydraulic efficiency of less than 2% in optimal cases. Both the experiments and CFD simulations were carried out for inclination angles between 10° and 38°. Afterwards CFD was used to simulate the effect of three different numbers of blades (3, 4 and 5) of an ASG with common design parameters. Overflow and gap leakage losses were found to increase at higher inclinations - these losses decreased with the addition of blades. For this particular ASG setup, the 5-bladed screw generated the most power. The 4 and 5-bladed screws had their highest efficiencies at inclination angles between 20° and 24.5°. The 3-bladed screw was found to have its highest efficiencies at comparatively lower inclination angles, with the simulations finding the optimal angle to be approximately 15.5°. Both CFD simulations and the experiments showed that overflow leakage started to happen much sooner at higher inclination angles, as expected.