Numerical investigations of a membrane morphing wind turbine blade under gust conditions

Abstract

Flexibility during flight using elasto-flexible membrane-material systems is an attractive solution regarding loads reduction under unsteady flow conditions. Based on this idea, a wind turbine blade with flexible surfaces is designed from the NASA-Ames Phase VI configuration and investigated under gust conditions. Two concepts are modelled, a flexible as well as a rigid blade geometry. While the rigid concept is only simulated using Unsteady Reynoldsaveraged Navier Stokes (URANS) method, the flexible blade is computed with Fluid-Structure Interaction simulations coupling URANS and Finite Element Method. In both cases, the fluid is modelled with a rigid-body rotation method. The latest enables to take into account the rotation of the blade and, for the flexible case, to simultaneously capture the strong relationship between the flow and the membrane's deformation. The resulting axial force, pressure distribution, vorticity, and flow field velocity are analyzed for both geometries. While the rigid geometry serves as a baseline, the flexible case is investigated, focusing on the difference between rigid and flexible configurations.