Numerical Modeling and Analysis of Breathing-Induced Displacements in a Wind Turbine Blade Trailing Edge Panel: A Parametric Study

As wind turbine blades become larger, the impact of edgewise gravity loads becomes increasingly critical. One significant problem related to these loads is known as “breathing,” which is the cyclic out-of-plane motion of the trailing edge panels. Breathing can cause several issues in wind turbine blades, including increased peel stresses in the adhesive joint at the trailing edge and in severe cases, result in trailing edge splitting. Despite its importance, there is a lack of comprehensive understanding of breathing and its effect on the blade’s trailing edge fatigue performance. This paper employs the DTU 10 MW reference wind turbine model to study the breathing effects, explicitly focusing on the displacement of trailing edge panels due to gravitational loads, aerodynamic loads, and their combined influence. Additionally, the study introduces modifications to the DTU 10 MW blade to evaluate the impact of various parameters on the breathing displacements such as different positions along the blade length, different points along the trailing edge panels, and the inclusion of an additional web near the trailing edge. The results of the study show that the breathing-induced displacement of trailing edge panels near the blade’s maximum chord region can be primarily dominated by gravitational loads. However, the displacement closer to the blade tip is mainly influenced by aerodynamic loads. Furthermore, the utilization of a third web reduces the overall displacement of panels, as it helps decrease the length of unsupported panels in the blade’s cross-section. By predicting the breathing-induced displacements in wind turbine blades, future research efforts will focus on understanding their effect on the peel stresses in the adhesive joint and fatigue life of wind turbine blades.