Influence of Reynolds number on the performance of small horizontal axis wind turbine with fixed speed operation

Abstract

ABSTRACT The Blade Element Momentum (BEM) theory is most commonly utilized to quickly assess the performance of horizontal axis wind turbine. However, the BEM theory requires the aerodynamic characteristic of the airfoil to evaluate the performance. Generally, the aerodynamic characteristics of airfoil in BEM theory for performance prediction of wind turbine with fixed rotor speed operation is obtained at an approximated fixed Reynolds number which may not accurately correspond to the operating Reynolds number over the blade. In the present work, the performance of a small wind turbine, with fixed rotor speed operation, and considering a range of approximated fixed Reynolds number (i.e., 0.5, 0.75, 1.00, and 1.25 million) and the operational Reynolds number over the blade for the aerodynamic characteristic of the airfoil has been evaluated and compared for a range of wind speeds i.e., 6, 8, 10, and 12 m/s. To incorporate the operational Reynolds number in the study, the aerodynamic characteristics of the airfoil have been mathematically represented as function of Reynolds number and angle of attack using an artificial neural network (ANN)-based model. The results suggest that inadequate Reynolds number consideration can led to high discrepancies up to 18.6% in power coefficient prediction.