No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

In order for wind-farm operators to deal with challenges regarding their fleet management, it is useful for them to estimate their units’ performance for different conditions. To perform such estimations, Computational Fluid Dynamics (CFD) may be used. This project focuses on the development of a CFD model for the aerodynamic analysis of wind turbine rotors, depending on their surface roughness. The work has been carried out in collaboration with the KTH Royal Institute of Technology and the Vattenfall AB R&D department. The open-source software OpenFOAM has been used to develop the desired model. A rigid body incompressible steady state, Reynolds-Averaged Navier-Stokes equations, k – ω SST CFD case has been set up. The NREL 5-MW rotor geometry has been used and the effect of four different surface roughness height values {1mm, 0.5mm, 100 μm, 30 μm} on its aerodynamic performance has been investigated for an incoming wind velocity of 10m/s. The referred roughness height values have been applied on the whole rotor surface. A 120° wedge type computational domain of unstructured mesh has been developed for the present simulations. The results indicate that a roughness-height increase leads to earlier flow separation over the blade suction side and increases the turbulent area of the boundary layer. That leads to a decrease for the extracted Torque and the Thrust force on the wind turbine rotor. Moreover, it is concluded that the rotor aerodynamic performance is more sensitive to low roughness heights rather than to high ones.

Wind-tunnel measurements are an important step during the windturbinedesign process. The goal of wind-tunnel tests is to estimate theoperational performance of the wind turbine, for example by measuringthe power and thrust coecients. Depending on the sizes of both thewind turbine and the test section, the eect of blockage can be substantial.Correction schemes for the power and thrust coecients havebeen proposed in the literature, but for high blockage and highly loadedrotors these correction schemes become less accurate.A new method is proposed here to calculate the eect a cylindricalwind-tunnel test section has on the performance of the wind turbine.The wind turbine is modeled with a simplied vortex model. Usingvortices of constant circulation to model the wake vortices, the performancecharacteristics are estimated. The test section is modeled witha panel method, adapted for this specic situation. It uses irrotationalaxisymmetric source panels to enforce the solid-wall boundary condition.Combining both models in an iterative scheme allows for thesimulation of the eect of the presence of the test-section walls on windturbines performace.Based on the proposed wind-tunnel model, a more general empirical correlationscheme is proposed to estimate the performance characteristicsof a wind turbine operating under unconned conditions by correctingthe performance measured in the conned wind-tunnel conguration.The proposed correction scheme performs better than the existing correctionschemes, including cases with high blockage and highly loadedrotors.