Title: Comparative study of the performances of twisted two-bladed and three-bladed airfoil shaped H-Darrieus turbines by computational and experimental methods

Authors: Rajat Gupta, Agnimitra Biswas

Addresses: National Institute of Technology Silchar, Silchar, Assam, 788010, India. ' National Institute of Technology Silchar, Silchar, Assam, 788010, India

Abstract: The vertical axis H-Darrieus turbines are simple in construction, self-starting, omni-directional, and self-regulating at all wind speeds. A comparative study of the performances of twisted two-bladed and three-bladed airfoil shaped H-Darrieus turbines was made. The models of the turbines were designed, fabricated, and tested in a subsonic wind tunnel. The power coefficients (Cp) and torque coefficients (Ct) were evaluated for ten numbers of height-to-diameter (H/D) ratios. Both Cp and Ct of the two-bladed turbine were higher than the three-bladed turbine. The maximum Cp for the two-bladed turbine was 0.237 and that for the three-bladed turbine was 0.151. The performances of the turbines were also compared computationally through 2D steady-state CFD simulations using Fluent 6.2 software. The agreement between the computational and experimental Cp was within ± 5.86%. The contour plots of static and dynamic pressures and velocity magnitudes were generated for chord Reynolds number of 8.5 × 104. At any position on the blade, dynamic pressure, velocity and also the velocity gradient between the ends were higher for the two-bladed turbine than the three-bladed turbine.

Keywords: H-Darrieus turbines; power coefficient; torque coefficient; tip speed ratio; H-D ratio; CFD analysis; comparative study; computational fluid dynamics; vertical axis turbines; two-bladed turbines; three-bladed turbines; dynamic pressure; velocity.

DOI: 10.1504/IJRET.2011.042731

International Journal of Renewable Energy Technology, 2011 Vol.2 No.4, pp.425 - 445

Available online: 30 Sep 2011 *

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