Abstract. In the present paper, numerical and experimental investigations of a model wind turbine with a diameter of 3.0 m are described. The study has three objectives. The first one is the provision of validation data. The second one is to estimate the influence of the wind tunnel walls by comparing measurements to simulated results with and without wind tunnel walls. The last objective is the comparison and evaluation of methods of high fidelity, namely computational fluid dynamics, and medium fidelity, namely lifting-line free vortex wake. The experiments were carried out in the large wind tunnel of the TU Berlin where a blockage ratio of 40 % occurs. With the lifting-line free vortex wake code QBlade, the turbine was simulated under far field conditions at the TU Berlin. Unsteady Reynolds-averaged Navier–Stokes simulations of the wind turbine, including wind tunnel walls and under far field conditions, were performed at the University of Stuttgart with the computational fluid dynamics code FLOWer. Comparisons among the experiment, the lifting-line free vortex wake code and the computational fluid dynamics code include on-blade velocity and angle of attack. Comparisons of flow fields are drawn between the experiment and the computational fluid dynamics code. Bending moments are compared among the simulations. A good accordance was achieved for the on-blade velocity and the angle of attack, whereas deviations occur for the flow fields and the bending moments.

Experimental results on turbulent developing pipe flow are reviewed. Upstream conditions are shown to have a large effect, in particular on the development of the velocity profile. It is demonstrated also that the blockage factor, when plotted against the Reynolds number defined with flow distance, is the parameter best suited to indicate the onset and termination of transition.

Abstract. Numerical and experimental investigations of a model wind turbine with a diameter of 3.0m are described in the present paper. The objectives of the study are the provision of validation data, the comparison and evaluation of methods of different fidelity and the assessment of the influence of the wind tunnel walls by comparison of measurements to simulations with and without wind tunnel walls. The experiments were carried out in the large wind tunnel of the TU Berlin. With the Lifting Line Free Vortex Wake (LLFVW) code QBlade, the turbine was simulated under far field conditions at the TU Berlin. 5URANS simulations were performed at the University of Stuttgart with the CFD code FLOWer for far field condition to draw a comparison to QBlade. Moreover, CFD simulations of the turbine in a wind tunnel were carried out, as the walls have a significant influence on the turbine performance.Comparisons between experiment, the LLFVW code and CFD include on-blade velocities, angle of attack and bending moments. Comparisons of flow fields are drawn between experiment and the CFD code. 10A good accordance was achieved for the flow fields, the on-blade velocity and the angle of attack, whereas deviations occur for the bending moments.

In the current paper a method to correct cross-talk effects for strain-gauge measurements is presented. The method is demonstrated on an experimental horizontal axis wind turbine. The procedure takes cross-moments (flap-wise on edgewise moments and vice versa) as well as axial acceleration into account. The results from the experimental setup are compared to numerical URANS calculations and the medium-fidelity code Qblade for a baseline case and two yawed inflow situations.

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