Water channel experiments of dynamic stall on Darrieus wind turbine blades

1986 ◽  
Vol 2 (5) ◽  
pp. 445-449 ◽  
Author(s):  
G. Brochier ◽  
P. Fraunie ◽  
C. Beguier ◽  
I. Paraschivoiu
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Water Channel ◽  
Dynamic Stall ◽  
Wind Turbine Blades

scholarly journals Stochastic Model for Aerodynamic Force Dynamics on Wind Turbine Blades in Unsteady Wind Inflow

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
M. R. Luhur ◽  
J. Peinke ◽  
M. Kühn ◽  
M. Wächter
Keyword(s):  
Stochastic Model ◽  
Wind Turbine ◽  
Aerodynamic Force ◽  
Turbine Blades ◽  
Stochastic Approach ◽  
Simulation Software ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Full Field ◽  
Blade Element

The paper presents a stochastic approach to estimate the aerodynamic forces with local dynamics on wind turbine blades in unsteady wind inflow. This is done by integrating a stochastic model of lift and drag dynamics for an airfoil into the aerodynamic simulation software AeroDyn. The model is added as an alternative to the static table lookup approach in blade element momentum (BEM) wake model used by AeroDyn. The stochastic forces are obtained for a rotor blade element using full field turbulence simulated wind data input and compared with the classical BEM and dynamic stall models for identical conditions. The comparison shows that the stochastic model generates additional extended dynamic response in terms of local force fluctuations. Further, the comparison of statistics between the classical BEM, dynamic stall, and stochastic models' results in terms of their increment probability density functions (PDFs) gives consistent results.

2D Numerical Simulations of Blade-Vortex Interaction in a Darrieus Turbine

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
E. Amet ◽  
T. Maître ◽  
C. Pellone ◽  
J.-L. Achard
Keyword(s):  
Numerical Analysis ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Water Channel ◽  
Dynamic Stall ◽  
Speed Ratio ◽  
Secondary Effects ◽  
Time Step ◽  
Tip Speed Ratio ◽  
Lift And Drag

The aim of this work is to provide a detailed two-dimensional numerical analysis of the physical phenomena occurring during dynamic stall of a Darrieus wind turbine. The flow is particularly complex because as the turbine rotates, the incidence angle and the blade Reynolds number vary, causing unsteady effects in the flow field. At low tip speed ratio, a deep dynamic stall occurs on blades, leading to large hysteresis lift and drag loops (primary effects). On the other hand, high tip speed ratio corresponds to attached boundary layers on blades (secondary effects). The optimal efficiency occurs in the middle range of the tip speed ratio where primary and secondary effects cohabit. To prove the capacity of the modeling to handle the physics in the whole range of operating condition, it is chosen to consider two tip speed ratios (λ=2 and λ=7), the first in the primary effect region and the second in the secondary effect region. The numerical analysis is performed with an explicit, compressible RANS k-ω code TURBFLOW, in a multiblock structured mesh configuration. The time step and grid refinement sensitivities are examined. Results are compared qualitatively with the visualization of the vortex shedding of Brochier (1986, “Water channel experiments of dynamic stall on Darrieus wind turbine blades,” J. Propul. Power, 2(5), pp. 445–449). Hysteresis lift and drag curves are compared with the data of Laneville and Vitecoq (1986, “Dynamic stall: the case of the vertical axis wind turbine,” Prog. Aerosp. Sci., 32, pp. 523–573).

Dynamic Stall on Rotating Airfoils: A Look at the N-Sequence Data from the NREL Phase VI Experiment

2013 ◽  
Vol 569-570 ◽  
pp. 611-619 ◽  
Author(s):  
Srinivas Guntur ◽  
Niels N. Sørensen ◽  
Scott Schreck
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Sequence Data ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Dynamic Stall ◽  
Wind Turbine Blades ◽  
Flow Solver ◽  
The Mean ◽  
Nrel Phase Vi

This paper presents an investigation on the combined effect of dynamic stall and rotational augmentation on wind turbine blades. Dynamic stall and rotational augmentation have previously been studied independently. The NREL Phase VI experiment was one large scale experiment that recorded 3D measurements on rotating and pitching airfoils, and using some these data the behaviour of the unsteady CL-α polars under the influence of rotation is investigated. Unsteady DES CFD computations of the Phase VI rotor in axial operation and continuous pitching conditions (reproducing conditions similar to the N-sequence experiments) for select cases have also been carried out using the in-house flow solver EllipSys3D. The resulting set of CL-α curves for the airfoils in rotation operating at various values of the frequency, the mean, and the amplitude of the angle of attack resulting from the CFD computations as well as those from the experiments are presented and discussed. Qualitative differences between dynamic stall occurrence on rotating and stationary airfoils are highlighted, procedures employed to extract the mean angle of attack from the available experimental data are discussed, and comments are made on the application of dynamic stall models in conjunction with 3D augmentation models on the rotating wind turbine blades.

scholarly journals Dynamic stall in vertical axis wind turbines: scaling and topological considerations

2018 ◽  
Vol 841 ◽  
pp. 746-766 ◽  
Author(s):  
Abel-John Buchner ◽  
Julio Soria ◽  
Damon Honnery ◽  
Alexander J. Smits
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vortex Shedding ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Vertical Axis Wind Turbines

Vertical axis wind turbine blades are subject to rapid, cyclical variations in angle of attack and relative airspeed which can induce dynamic stall. This phenomenon poses an obstacle to the greater implementation of vertical axis wind turbines because dynamic stall can reduce turbine efficiency and induce structural vibrations and noise. This study seeks to provide a more comprehensive description of dynamic stall in vertical axis wind turbines, with an emphasis on understanding its parametric dependence and scaling behaviour. This problem is of practical relevance to vertical axis wind turbine design but the inherent coupling of the pitching and velocity scales in the blade kinematics makes this problem of more broad fundamental interest as well. Experiments are performed using particle image velocimetry in the vicinity of the blades of a straight-bladed gyromill-type vertical axis wind turbine at blade Reynolds numbers of between 50 000 and 140 000, tip speed ratios between $\unicode[STIX]{x1D706}=1$ to $\unicode[STIX]{x1D706}=5$, and dimensionless pitch rates of $0.10\leqslant K_{c}\leqslant 0.20$. The effect of these factors on the evolution, strength and timing of vortex shedding from the turbine blades is determined. It is found that tip speed ratio alone is insufficient to describe the circulation production and vortex shedding behaviour from vertical axis wind turbine blades, and a scaling incorporating the dimensionless pitch rate is proposed.

On the Use of Velocity Data for Load Estimation of a VAWT in Dynamic Stall

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Carlos J. Simão Ferreira ◽  
Gerard J. W. van Bussel ◽  
Gijs A. M. van Kuik ◽  
Fulvio Scarano
Keyword(s):  
Velocity Field ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Pressure Sensors ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Velocity Data ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Image Velocimetry

This paper focuses on evaluating the feasibility of estimating loads on vertical axis wind turbine blades in dynamic stall with velocity data acquired with Particle Image Velocimetry. The study uses numerical simulation data of a 2D Vertical Axis Wind Turbine in dynamic stall to verify sources of error and uncertainty and estimate the accuracy of the method. The integration of the forces from the velocity field overcomes the difficulties and limitations presented by pressure sensors for estimating the local section loads, but adds the difficulty in determining the correct velocity field and its time and spatial derivatives. The analysis also evaluates the use of phase-locked average data as an estimator of average loads.

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