Aeroelastic Simulation of a Wind Turbine Under Turbulent and Sheared Conditions

Abstract

The simulation of turbulence introduced in Chap. 29 is extended in this chapter by adding a sheared inflow, also modelled using vortex particles. The chapter starts by discussing the representation of shear in vortex methods. The notions of frozen shear and unfrozen shear are introduced and the vorticity equations are developed for these situations. It is shown that vortex methods tend to omit a term witch is non-negligible when sheared-inflow simulations are performed. The methods perform frozen shear simulation in an erroneous way, which implies that the turbine wake is deflected upward. The numerical implementation of unfrozen shear is discussed and a solution referred to as a Neumann-to-Dirichlet map (or external map) is used to account for the infinite support of the vorticity and the finite computational domain. The method is then applied for full-blown aeroelastic simulations of a wind turbine with shear and turbulence. The possibility to perform aeroelastic simulations of wind turbine under sheared and turbulent conditions using vortex methods is demonstrated. The modelling of turbulence is described in Chap. 29. The elasticity is handled by performing a coupling of the aerodynamic vortex code with the aero-servo-elastic solver HAWC2. The large eddy simulations (LES) performed with the vortex code confirms that the wake should not follow an upward motion when the shear is unfrozen. Results from this chapter are published in the article titled “Aeroelastic large eddy simulations using vortex methods: unfrozen turbulent and sheared inflow” (Branlard et al., J. Phys. Conf. Ser. 625, 2015, [2]).