Aerodynamic Damping and Seismic Response of Horizontal Axis Wind Turbine Towers

Abstract

AbstractAerodynamic damping has an important effect on the seismic response of horizontal axis wind turbines (HAWTs). Some researchers have estimated that aerodynamic damping in operational HAWTs is ∼5% of critical in the fore-aft direction (i.e., perpendicular to the rotor and parallel to the prevailing wind). In most recent studies, dynamic analyses of HAWT towers under seismic loads have neglected aerodynamic damping, and this assumption has significant implications in the predicted seismic response. This paper presents a closed-form solution for the aerodynamic damping of HAWTs responding dynamically in the fore-aft and side-to-side directions. The formulation is intended as a convenient method for structural earthquake engineers to include the effect of aerodynamic damping in the seismic analysis of HAWTs. The formulation is based on blade element momentum theory and is simplified by assuming a rigid rotor subjected to a steady and uniform wind oriented perpendicular to the rotor plane. This paper ex...