The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Niels N Sorensen - One of the best experts on this subject based on the ideXlab platform.
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characterization of the unsteady flow in the Nacelle region of a modern wind turbine
Wind Energy, 2011Co-Authors: Frederik Zahle, Niels N SorensenAbstract:A three-dimensional Navier–Stokes solver has been used to investigate the flow in the Nacelle region of a wind turbine where anemometers are typically placed to measure the flow speed and the turbine yaw angle. A 500 kW turbine was modelled with rotor and Nacelle geometry in order to capture the complex separated flow in the blade root region of the rotor. A number of steady state and unsteady simulations were carried out for wind speeds ranging from 6 m s−1 to 16 m s−1 as well as two yaw and tilt angles. The flow in the Nacelle region was found to be highly unsteady, dominated by unsteady vortex shedding from the cylindrical part of the blades, which interacted with the root vortices from each blade, generating high-velocity gradients. As a consequence, the Nacelle wind speed and the Nacelle flow angle were found to vary significantly with the height above the Nacelle surface. The Nacelle anemometry showed significant dependence on both yaw and tilt angles with yaw errors of up to 10 degrees when operating in a tilted inflow. Copyright © 2010 John Wiley & Sons, Ltd.
Stefano Leonardi - One of the best experts on this subject based on the ideXlab platform.
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effect of tower and Nacelle on the flow past a wind turbine
Wind Energy, 2017Co-Authors: Christian Santoni, Kenneth Carrasquillo, Isnardo Arenasnavarro, Stefano LeonardiAbstract:Large eddy simulations (LES) of the flow past a wind turbine with and without tower and Nacelle have been performed at 2 tip speed ratios (TSR, λ=ωR/U∞), λ=3 and 6, where the latter corresponds to design conditions. The turbine model is placed in a virtual wind tunnel to reproduce the “Blind test 1” experiment performed at the Norwegian University of Science and Technology (NTNU) closed-loop wind tunnel. The wind turbine was modeled using the actuator line model for the rotor blades and the immersed boundary method for the tower and Nacelle. The aim of the paper is to highlight the impact of tower and Nacelle on the turbine wake. Therefore, a second set of simulations with the rotating blades only (neglecting the tower and Nacelle) has been performed as reference. Present results are compared with the experimental measurements made at NTNU and numerical simulations available in the literature. The tower and Nacelle not only produce a velocity deficit in the wake but they also affect the turbulent kinetic energy and the fluxes. The wake of the tower interacts with that generated by the turbine blades promoting the breakdown of the tip vortex and increasing the mean kinetic energy flux into the wake. When tower and Nacelle are modeled in the numerical simulations, results improve significantly both in the near wake and in the far wake.
Frederik Zahle - One of the best experts on this subject based on the ideXlab platform.
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characterization of the unsteady flow in the Nacelle region of a modern wind turbine
Wind Energy, 2011Co-Authors: Frederik Zahle, Niels N SorensenAbstract:A three-dimensional Navier–Stokes solver has been used to investigate the flow in the Nacelle region of a wind turbine where anemometers are typically placed to measure the flow speed and the turbine yaw angle. A 500 kW turbine was modelled with rotor and Nacelle geometry in order to capture the complex separated flow in the blade root region of the rotor. A number of steady state and unsteady simulations were carried out for wind speeds ranging from 6 m s−1 to 16 m s−1 as well as two yaw and tilt angles. The flow in the Nacelle region was found to be highly unsteady, dominated by unsteady vortex shedding from the cylindrical part of the blades, which interacted with the root vortices from each blade, generating high-velocity gradients. As a consequence, the Nacelle wind speed and the Nacelle flow angle were found to vary significantly with the height above the Nacelle surface. The Nacelle anemometry showed significant dependence on both yaw and tilt angles with yaw errors of up to 10 degrees when operating in a tilted inflow. Copyright © 2010 John Wiley & Sons, Ltd.
Rolf Kumme - One of the best experts on this subject based on the ideXlab platform.
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Procedure for torque calibration under constant rotation investigated on a Nacelle test bench
Sensors and Measuring Systems; 19th ITG GMA-Symposium, 2018Co-Authors: Paula Weidinger, Gisa Foyer, Stefan Kock, Jonas Gnauert, Rolf KummeAbstract:In order to determine the efficiency of multi-MW Nacelles, the torque measurement of multi-MW Nacelle test benches has to be performed with an accuracy of approximately 0.2%. To this end, the torque transducer has to be traced to national standards in the MNm range. This can be done by using a new torque calibration procedure under constant rotation performed on a Nacelle test bench. The results, in the form of an indication deviation including the measurement uncertainty of less than 0.22%, are discussed in this paper.
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mn m torque calibration for Nacelle test benches using transfer standards
ACTA IMEKO, 2016Co-Authors: Christian Schlegel, Holger Kahmann, Rolf KummeAbstract:To verify all technical aspects of wind turbines, more and more Nacelle test benches have come into operation. One crucial parameter is the initiated torque in the Nacelles, which amounts to several MN·m. So far, no traceable calibration to national standards has been performed in such test benches. The paper will show calibration possibilities which already exist and also show future prospects.
Christian Santoni - One of the best experts on this subject based on the ideXlab platform.
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effect of tower and Nacelle on the flow past a wind turbine
Wind Energy, 2017Co-Authors: Christian Santoni, Kenneth Carrasquillo, Isnardo Arenasnavarro, Stefano LeonardiAbstract:Large eddy simulations (LES) of the flow past a wind turbine with and without tower and Nacelle have been performed at 2 tip speed ratios (TSR, λ=ωR/U∞), λ=3 and 6, where the latter corresponds to design conditions. The turbine model is placed in a virtual wind tunnel to reproduce the “Blind test 1” experiment performed at the Norwegian University of Science and Technology (NTNU) closed-loop wind tunnel. The wind turbine was modeled using the actuator line model for the rotor blades and the immersed boundary method for the tower and Nacelle. The aim of the paper is to highlight the impact of tower and Nacelle on the turbine wake. Therefore, a second set of simulations with the rotating blades only (neglecting the tower and Nacelle) has been performed as reference. Present results are compared with the experimental measurements made at NTNU and numerical simulations available in the literature. The tower and Nacelle not only produce a velocity deficit in the wake but they also affect the turbulent kinetic energy and the fluxes. The wake of the tower interacts with that generated by the turbine blades promoting the breakdown of the tip vortex and increasing the mean kinetic energy flux into the wake. When tower and Nacelle are modeled in the numerical simulations, results improve significantly both in the near wake and in the far wake.
