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The Science of Making Torque from Wind (TORQUE 2018)

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Room: BL.27.03
Chaired by: Carlos Simao Ferreira | TUDelft
Topic: AA. Aerodynamics and Aeroacoustics
Form of presentation: Oral
Duration: 110 minutes

Authors:
Sophie Baleriola, Annie Leroy, Stéphane Loyer, Philippe Devinant, Sandrine Aubrun

Abstract:
This study focuses on the experimental implementation of a fluidic lift control strategy on a wind turbine blade with the objective of reducing the aerodynamic load fluctuations on blades. Blades are equipped with a row of blowing jets located in the vicinity of the rounded trailing-edge of the airfoil. The effect of the actuation is to modify the flow near the trailing-edge and change the whole pressure distribution around the airfoil as well as the spanwise lift distribution of the blade. Load, flap bending moment and pressure measurements as well as Particle Image Velocimetry (PIV) show respectively the actuation effectiveness in terms of load modification and flow topology alteration.

Authors:
Delphine De Tavernier, Carlos Ferreira, Ang Li, Uwe Schmidt Paulsen, Helge Aagaard Madsen

Abstract:
In this research the effect of vertical-axis wind turbines (VAWTs) in double-rotor conguration on the power generation and flow characteristics is identied. Simulations are performed using a 2D vortex/panel method for different double-rotor congurations and various tip speed ratios, solidities, rotor spacings and wind directions. VAWTs take advantage of a neighbouring rotor by wake contraction and flow acceleration in between the rotors causing the flow characteristics to be more favourable. This effect is highly depending on the rotor parameters. With this thorough analysis, we want to work towards the physical understanding of the power enhancement of the double-rotor VAWT.

Authors:
Vinit Dighe

Abstract:
This paper aims to study the aerodynamic performance of ducted wind turbines (DWT) using inviscid and viscous flow calculations. In particular, the non-linear mutual interaction between a duct and the rotor forces are accounted for. For the proposed method, the inviscid calculations evaluate the performance of the system for each prescribed duct-rotor load configuration, and the viscous solver is used to investigate the local and global features of the flow through  DWT. The analysis shows the opportunity to significantly increase the overall aerodynamic performance of the DWT by a correct choice of an optimal rotor loading for a given duct geometry.

Authors:
Julien Deparday, Karen Mulleners

Abstract:
To improve wind turbine design, low order models that accurately predict the aerodynamic performance are desirable. Dynamic stall dominates the aerodynamic performance, the robustness, and the wake dynamics of vertical axis wind turbines. To better assess the dynamic stall onset and its associated unsteady effects, this paper analyzes experimentally the evolution of the leading edge suction vector on a sinusoidal pitching airfoil. The time evolution of the magnitude of the leading edge suction is similar for various pitching motions. At the first order, a unique maximum of the magnitude is found when the vortex formation begins. Two distinct stages in the temporal development of the leading edge suction magnitude are identified which are linked to different flow topologies and vortex distributions occurring during the dynamic stall development. The direction of the leading edge suction evolves also similarly for various pitching motions. The vortex dynamics and the aerodynamic load evolution during the dynamic stall and the reattachment phase are linked with the evolution of the leading edge suction. Comprehensive time-scales and amplitudes of aerodynamic loads are quantified allowing to reduce the empiricism of existing low order models used to design vertical axis wind turbine.

Authors:
Thanasis K Barlas, Anders S Olsen, Helge A Madsen, Tom L Andersen, Qing Ai, Paul M Weaver

Abstract:
A testing campaign utilizing DTU’s outdoor rotating rig is described, where a novel morphing flap system developed in collaboration with the University of Bristol within the Innwind.eu project has been evaluated and successfully demonstrated. In addition, the aerodynamic performance of ECN’s newly designed aerofoil has been evaluated in atmospheric conditions. The morphing wing is shown to achieve good performance in terms of aerodynamic lift control, and compares well with computational fluid dynamics predictions. Moreover, simple feed-forward controller implementations, also utilizing inflow sensors, show promising results in terms of dynamic load alleviation.

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