In the analysis of the aerodynamic performance of wind turbines, the need to account for the effects of rotation is important as engineering models often failed to predict these phenomena. Investigations are carried out by employing an unsteady computational fluid dynamics (CFD) approach on a generic 10 MW AVATAR (Advanced Aerodynamic Tools for Large Rotors) blade. The focus of the studies is the evaluation of the 3D effect characteristics on thick airfoils in the root area. For preliminary studies, 2D simulations of the airfoils constructing the blade and 3D simulations of the turbine near the rated conditions are carried out. The 2D simulations are in good agreement with available measurements within the linear lift region, but the accuracy deteriorates in the post stall region. For the 3D wind turbine rotor results, the prediction is consistent with other CFD computations obtained from the literature. Further calculations of the rotor are conducted at 5 different wind speeds ranging from below to above the rated conditions, which correspond to 5 different angles of attack. The CFD simulations demonstrate that the lift coefficient increases in the blade root region compared to the 2D conditions caused by the centrifugal pumping and Coriolis force via the reduction of the boundary layer thickness and separation delay. The Coriolis force effect decreases with the increasing wind speed and radial position. In addition, the aerodynamic behaviour of the blade inboard region is influenced by the shedding direction of the trailing vortices. The occurrence of downwash is observed causing a local increase in the drag coefficient.
This work presents an investigation on different methods for the calculation of the angle of attack and the underlying induced velocity on wind turbine blades using data obtained from three-dimensional Computational Fluid Dynamics (CFD). Several methods are examined and their advantages, as well as shortcomings, are presented. The investigations are performed for two 10MW reference wind turbines under axial inflow conditions, namely the turbines designed in the EU AVATAR and INNWIND.EU projects. The results show that the evaluated methods are in good agreement with each other at the mid-span, though some deviations are observed at the root and tip regions of the blades. This indicates that CFD results can be used for the calibration of induction modeling for Blade Element Momentum (BEM) tools. Moreover, using any of the proposed methods, it is possible to obtain airfoil characteristics for lift and drag coefficients as a function of the angle of attack. Nomenclature ρ Air density [kg m −3 ] Γ Circulation [m 2 s −1 ]
Memories are classified as consolidated (stable) or labile according to whether they withstand amnestic treatment, or not. In contrast to the general prevalence of this classification, its neuronal and molecular basis is poorly understood. Here, we focused on consolidated and labile memories induced after a single cycle training in the Drosophila aversive olfactory conditioning paradigm and we used mutants to define the impactofcAMPsignals.AtthebiochemicallevelwereportthatcAMPsignalsmisrelatedineither rutabaga(rut)ordunce (
In today's wind energy research, comparisons of low‐fidelity aerodynamic models with CFD simulations are common practice. While the approach for loads with respect to the rotor‐plane coordinate system such as distributed driving force or thrust is straightforward, a comparison of aerodynamic characteristics is more challenging. The radial distributions of lift, drag, and moment coefficient depend on the local angle of attack and inflow velocity, which cannot be directly determined from the flow field. It requires the elimination of the influence of the rotor blade's bound circulation and also involves the step from a three‐dimensional flow field to quantities, which depend on the blade radius. The present investigation analyzes 4 different approaches to determine the angle of attack and inflow velocity from three‐dimensional rotor simulations. In addition to 3 existing methods, a new line average technique is presented. It eliminates the effect of bound circulation by averaging along a closed shape, which is symmetric to the quarter‐chord point. All methods are assessed in cases with successively increasing complexity. The observed discrepancies are assigned to a different consideration of trailing and shed vortices. The line average approach was found to be a valuable alternative to existing approaches especially in unsteady cases and regarding the outer or tip sections of the rotor blade.
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