Passive load alleviation on wind turbine blades from aeroelastically driven selectively compliant morphing

Abstract

Load alleviation control is highly desirable to reduce penalties associated with the added structural mass required to withstand rare load scenarios. This is particularly true for wind turbine designs incorporating long-span blades. Implementation of compliance-based morphing structures to modify the lift distribution passively has the potential to mitigate the impact of rare, but integrally threatening, loads on wind turbine blades while limiting the addition of actuation and sensing systems. We present a novel passive load alleviation concept based on a morphing flap exhibiting selective compliance from an embedded bistable element. A multifidelity, aeroelastic tool is used to study the shape adaptability of a morphing flap indicating that passive changes from high lift generation to load alleviation configurations can be achieved by exploiting the energy of the flow. This mechanism offers a method to reduce catastrophic peak loads potentially, thus offering the possibility to lower the overall structural weight of wind turbine blades.