Experimental Investigation of Aerodynamic Performance of a Wind Turbine Blade Undergoing Pure Pitch and Plunge Motions

Abstract

In this paper, extensive experimental tests were carried out for an aerodynamic characterization of the airfoil cross-section of a wind turbine blade. The wind turbine blade cross-sections are usually exposed to unsteady pitch and plunge oscillations. One way to increase the power of blade, is to improve it’s aerodynamic performance, so it is necessary to study and compare the unsteady aerodynamic behavior of the airfoil. The aerodynamic behavior of turbine blades are dependent on several parameters including initial angle of attack, reduced frequency and oscillation amplitude. In this study, reduced frequency and oscillation amplitude assumed constant and the initial angle of attack of the model was varied in both pitch and plunge oscillations. Therefore, the aerodynamic behavior of the model was investigated under motions with similar conditions before, near and after of the static stall angles of attack. The vertical displacement of the plunge motion was selected such that the equivalent angle of attack in plunge motion is approximately equal to the oscillation amplitude in the pitch motion. All tests were conducted at a constant Reynolds number of 0.27×106. The practical results of this study indicate that the choice of a pitch or plunge motion, granted both are feasible, depends on the requirements and significance of aerodynamic forces and the decisive for ruling cannot be made about which motion guarantees the best aerodynamic performance at all angles of attack.