Effects of the Blades Orientation on a Cross-Flow Water Turbine Performance

Abstract

Efficiency and powerimprovement of cross-flow turbines harnessing rivers and ocean water energy isa key issue. Therefore, in this paper, we present the results of an experimental investigation on the effects of the blades orientation ona cross-flow water turbineperformance. Four similar test models (same dimensions and blades) bur for different blades orientation angle i = 1.75 °, 4.5 °, - 1.75 ° and - 4.5 ° have been tested to evaluate theperformance of this vertical axis water turbine (VAWT), for several water flow velocities V varying from0.3 to 0.59 m/s, which correspond to a water free flow Reynolds number of 2.08 104 to 4.36 104. An analysis of theseexperimental results has shown that the best performance (biggest power andpower coefficient) was obtained for the test model with its blades orientationangle set to 1.75 ° and the worst performance was given for the test model bladesorientation of -4.5 °. A comparison of the present results with those obtained in aprevious experimentation for a similar test model but with i = 0 °, has shown that the test model with its blades orientation angle fixed to1.75 °, furnished relative increases of optimum mechanical power and ofcorresponding power coefficient respectively as much as 82 % and 67 % withrespect to the results for i = 0 °, at a flow velocity equal to 0.37 m/s.While, the test model, with negative angle of -4.5 °, gave smaller generatedpower and power coefficient with corresponding relative decreases of about 49 %and 36 % with respect to those obtained for the test model with its bladesfixed at 0 °.