Analysis of variations in annual energy production based on types of suction side erosion at the blade tip of a wind turbine using numerical simulation

Abstract

ABSTRACT Wind turbine blades are prone to damage by airborne particulate matter; hence, periodic blade inspection is necessary for maintenance. However, quantitative data on wind turbine performance reduction due to erosion are lacking. Herein, erosion conditions were classified into four levels based on the erosion area in long-term operated wind turbine blades. Transient three-dimensional computational fluid dynamics analysis was performed by applying the suction side erosion shape to the tip airfoil of the National Renewable Energy Laboratory’s 5 MW blade. In the early stage, irregular erosion of the airfoil’s leading edge resulted in the development of a reverse pressure gradient inside the boundary layer and a larger recirculation area of the trailing edge. Thus, the lift coefficient of the airfoil decreased by up to 30%, whereas the drag coefficient increased by over 100%. The wind turbine output curve calculated using aeroelastic software showed that the worst erosion condition decreased output by 2.54%. Annual energy production had declined by up to 2% based on the annual average wind speed; therefore, immediately repairing erosion can minimize the loss of energy production.