Power Performance of an Inversely Tapered Wind Rotor and its Air Flow Visualization Analysis Using Particle Image Velocimetry (PIV)

Abstract

Wind turbine rotors capture energy from moving wind, their capacity to perform this function depends on the coefficient of power (Cp) of the rotor. Through proper aerodynamic design, a rotor’s performance can be optimized to take advantage of the smallest available wind speed at any time to produce energy. In this research a computational fluid dynamics simulation was performed to model the best optimum dimensions of an inversely tapered rotor blade using Clark Y airfoil type rotor of 0.6 m diameter. The optimal design values obtained include; tip speed ratio (TSR) of 2.5, lift coefficient to drag coefficient ratio of 1.1 and pitch angle of 8 degrees Using blade element momentum (BEM), the wing profile of each section of the blade was calculated and designed. The unique inverse tapering was done to achieve a better efficiency at the low wind speed range. This was used to fabricate a three blade rotor using carbon composites which was tested in the wind tunnel for Cp. Results showed very good performance of the inverse tapered type as compared with the tapered rotors. The maximum coefficient of power for the inversely tapered was found to be 0.313 at 8 m/s. Visualization test and particle image velocimetry (P.I.V). analysis showed that the inversely tapered rotor is more effective in converting wind power into shaft power than the tapered.