Niels Troldborg

Comprehensive Aerodynamic Analysis of a 10 MW Wind Turbine Rotor Using 3D CFD

This article describes a comprehensive aerodynamic analysis carried out on the DTU 10 MW Reference Wind Turbine (DTU 10MW RWT), in which 3D CFD simulations were used to analyse the rotor performance and derive airfoil aerodynamic characteristics for use in aero-elastic simulation tools. The 3D CFD airfoil data derived using the Azimuthal Averaging Technique (AAT) was compared to airfoil data based on 2D CFD simulations on airfoil sections in combination with an array of 3D-correction engineering models, which indicated that the model by Chaviaropoulos and Hansen was in best agreement with the 3D CFD predictions. BEM simulations on the DTU 10MW RWT using the AAT-based airfoil data were carried out and compared to BEM simulations using the original airfoil data and the 3D CFD results, which showed clear improvements, particularly on the inner part of the rotor. Finally, 3D unsteady Detached Eddy Simulations (DES) were carried out to derive airfoil data for standstill conditions in the range of angles of attack of AOA = [-180, 180] deg. showing distinct differences compared to the baseline data.

Comparison of wind turbine wake properties in non-uniform inflow predicted by different rotor models

The wake of the 2MW NM80 wind turbine subject to non-uniform and laminar inflow conditions is simulated using CFD with a fully resolved rotor geometry, an actuator line method and actuator disc method, respectively and in all simulations the wake properties are compared. Based on the comparison the strengths and limitations of the models are pointed out.

Simulations of wind turbine rotor with vortex generators

This work presents simulations of the DTU 10MW wind turbine rotor equipped with vortex generators (VGs) on the inner part of the blades. The objective is to study the influence of different VG configurations on rotor performance and in particular to investigate the radial dependence of VGs, i.e. how VGs at one section of the blade may affect the aerodynamic characteristics at other radial positions. Furthermore, the performance of different sections on the blade is compared to their corresponding performance in 2D flow.

An Attempt to Characterize the Structure of Wake Turbulence Using a Combined Experimental and Numerical Approach

This paper describes a combined numerical and experimental effort to characterize the structure of wake turbulence. The numerical approach is based on detailed LES. The experimental approach is based on an innovative analysis applied on full-scale wake recordings obtained using a newly developed 2D lidar technology. Consistency between the numerical and experimental approaches in terms of wake turbulence characteristics is observed. Compared to conventional atmospheric boundary layer (ABL) turbulence, the wake turbulence is inhomogeneous with reduced length scales, increased intensity, and increased coherence decay.