Experimental and Numerical Evaluation of Performance of a Variable Pitch Vertical-Axis Wind Turbine

Abstract

Abstract The research work depicts the study of the comparison of a 1 kW fixed pitch vertical-axis wind turbine (VAWT) and a variable pitch VAWT via analytical, numerical, and experimental results. Being an emerging technology, wind turbine is becoming a source of attraction for the researchers. The VAWT in comparison to the horizontal-axis wind turbine (HAWT) has shown numerous benefits. The fundamental purpose of this study is to maximize the output power and output torque of the wind turbine. For achieving an improved output, a novel and unique mechanism, termed as pitching mechanism, is employed that follows the variable pitch concept. The mathematical modeling was performed for the straight blade variable pitch VAWT and for the fixed rotor. The four-bar mechanism was developed to execute the variable pitch mechanism and implemented in the form of the computer-aided design, model. A scaled down three-dimensional (3D) model of the rotor was manufactured using the 3D printing technique. The aerodynamic forces such as lift and drag were measured upon the rotor as per the testing on the rotor in the wind tunnel. Computational fluid dynamics (CFD) simulations were run for the fixed pitch and the variable pitch rotor. The transient analysis was performed for the azimuthal angle ranging from 0 to 360 deg and for a pitch angle varying from +25 to −25 deg in ansys software. The comparative study was undertaken, keeping in view the analytical, simulation, and experimental results. A worthy agreement was observed among analytical, software, and experimental results, and a promising increase in power and torque was observed due to the introduction of the variable pitch mechanism. The power produced by the variable pitch design showed a significant increase in the power production compared to the fixed pitch design. The numerical and experimental values of cp for the variable pitch design were quite comparable.