Challenges in Modeling the Unsteady Aerodynamics of Wind Turbines

2002 ◽  
Author(s):  
J. Gordon Leishman
Keyword(s):  
Velocity Field ◽  
Wind Turbines ◽  
Unsteady Aerodynamics ◽  
Dynamic Stall ◽  
Experimental Measurements ◽  
Fundamental Limits ◽  
Unsteady Aerodynamic ◽  
Modeling Techniques ◽  
Induced Velocity

Many of the aerodynamic phenomena contributing to the observed effects on wind turbines are now known, but the details of the flow are still poorly understood and are challenging to predict accurately, issues discussed herein include the modeling of the induced velocity field produced by the vortical wake behind the turbine, the various unsteady aerodynamic issues associated with the blade sections, and the intricacies of dynamic stall. Fundamental limits exist in the capabilities of all models, and misunderstandings or ambiguities can also arise in how these models should be properly applied. A challenge for analysts is to use complementary experimental measurements and modeling techniques to better understand the aerodynamic problems found on wind turbines, and to develop more rigorous models with wider ranges of application.

Prediction of Wind Turbine Rotor Loads Using the Beddoes-Leishman Model for Dynamic Stall

1995 ◽  
Vol 117 (3) ◽  
pp. 200-204 ◽  
Author(s):  
K. Pierce ◽  
A. C. Hansen
Keyword(s):  
Wind Turbines ◽  
Aerodynamic Force ◽  
Unsteady Aerodynamics ◽  
Turbine Rotor ◽  
Dynamic Stall ◽  
University Of Utah ◽  
Horizontal Axis Wind Turbines ◽  
Wind Tunnel Data ◽  
The University ◽  
Wind Turbine Rotor

The Beddoes-Leishman model for unsteady aerodynamics and dynamic stall has recently been implemented in YawDyn, a rotor analysis code developed at the University of Utah for the study of yaw loads and motions of horizontal axis wind turbines. This paper presents results obtained from validation efforts for the Beddoes model. Comparisons of predicted aerodynamic force coefficients with wind tunnel data and data from the combined experiment rotor are presented. Also, yaw motion comparisons with the combined experiment rotor are presented. In general the comparisons with the measured data are good, indicating that the model is appropriate for the conditions encountered by wind turbines.

Extensive Validation of HAWT Unsteady Modelling Using BEM and CFD

2020 ◽  
Author(s):  
Raffaele Peraro ◽  
Luca Menegozzo ◽  
Andrea Dal Monte ◽  
Ernesto Benini
Keyword(s):  
Wind Turbines ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Dynamic Stall ◽  
Flow Conditions ◽  
Machine Performance ◽  
Horizontal Axis Wind Turbines ◽  
Computational Fluid Dynamics Cfd ◽  
Nrel Phase Vi ◽  
Blade Element

Abstract The present work aims to present two different approaches to model the unsteady aerodynamics of horizontal-axis wind turbines (HAWTs). A complete and extensive comparison has been established between the results obtained using a low-fidelity calculation tool, as the Blade Element Momentum (BEM), and a high-fidelity technique, as the Computational Fluid Dynamics (CFD). Regarding the first calculation strategy, an accurate revision in polar diagrams calculation and the implementation of yaw and dynamic stall routines have endowed the BEM code to predict the machine performance under unsteady flow conditions. In order to achieve an accurate validation, the proposed BEM solver has been tested on AOC 15/50 and NREL Phase VI wind turbines. Referring to CFD techniques, a three-dimensional unsteady model has been improved to study the aerodynamic behaviour of the machine in case of yawed incoming wind.

Surrogate-Based Recurrence Framework Approach to Unsteady Aerodynamic Modeling of Wind Turbine Airfoils

2013 ◽  
Author(s):  
Pengyin Liu ◽  
Xiaocheng Zhu ◽  
Guohua Yu ◽  
Zhaohui Du
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Unsteady Aerodynamics ◽  
Aerodynamic Characteristics ◽  
Time Varying ◽  
Analysis And Design ◽  
Aerodynamic Modeling ◽  
Unsteady Aerodynamic ◽  
Cfd Method ◽  
Turbine Airfoils

This paper proposes a method for predicting unsteady aerodynamics of wind turbine airfoils using surrogate-based recurrence framework (SBRF) method. Using specified simulation results generated by the CFD method in some conditions, the unsteady aerodynamic model could be established by the Kriging surrogate model. Then, time-domain predictions of unsteady lift, moment, and drag in different conditions can be gained by the SBRF method with minimal computational expense. Some parameters have been set according to the operational condition of wind turbines so as to describe the unsteady aerodynamic modeling problem. The unsteady aerodynamic performance of the wind turbine airfoils in some training conditions is carried out by the commercial CFD simulator CFX, the results of which could be utilized to build the SBRF. Then the predicted time-varying aerodynamic characteristics of wind turbine airfoils in the validated condition could be obtained by the SBRF method and the CFD simulation, respectively. It is revealed from the results that the time-varying aerodynamic characteristics of wind turbine airfoils in most dynamic stall cases can accurately approximate by the SBRF method. In addition, the SBRF method has relatively less computational cost compared with the CFD method. Therefore, it can be used as the foundation of aero-elastic analysis and design optimization studies of wind turbines.

3D measurement and simulation of surface acoustic wave driven fluid motion: a comparison

Lab on a Chip ◽  
2017 ◽  
Vol 17 (12) ◽  
pp. 2104-2114 ◽  
Author(s):  
Florian Kiebert ◽  
Stefan Wege ◽  
Julian Massing ◽  
Jörg König ◽  
Christian Cierpka ◽  
...  
Keyword(s):  
Velocity Field ◽  
Acoustic Wave ◽  
Numerical Simulations ◽  
Surface Acoustic Wave ◽  
Acoustic Streaming ◽  
Fluid Motion ◽  
Experimental Measurements ◽  
3D Measurement ◽  
Induced Velocity

We present a quantitative 3D comparison between experimental measurements and numerical simulations of the acoustic streaming induced velocity field.

Blade Dynamic Stall Vortex Kinematics for a Horizontal Axis Wind Turbine in Yawed Conditions*

2001 ◽  
Vol 123 (4) ◽  
pp. 272-281 ◽  
Author(s):  
Scott J. Schreck ◽  
Michael C. Robinson ◽  
M. Maureen Hand ◽  
David A. Simms
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Unsteady Aerodynamics ◽  
Horizontal Axis ◽  
Dynamic Stall ◽  
Deformation Analysis ◽  
Horizontal Axis Wind Turbine ◽  
The Impact ◽  
Vortex Kinematics

Horizontal axis wind turbines routinely suffer significant time varying aerodynamic loads that adversely impact structures, mechanical components, and power production. As lighter and more flexible wind turbines are designed to reduce overall cost of energy, greater accuracy and reliability will become even more crucial in future aerodynamics models. However, to render calculations tractable, current modeling approaches admit various approximations that can degrade model predictive accuracy. To help understand the impact of these modeling approximations and improve future models, the current effort seeks to document and comprehend the vortex kinematics for three-dimensional, unsteady, vortex dominated flows occurring on horizontal axis wind turbine blades during non-zero yaw conditions. To experimentally characterize these flows, the National Renewable Energy Laboratory Unsteady Aerodynamics Experiment turbine was erected in the NASA Ames 80 ft×120 ft wind tunnel. Then, under strictly-controlled inflow conditions, turbine blade surface pressures and local inflow velocities were acquired at multiple radial locations. Surface pressure histories and normal force records were used to characterize dynamic stall vortex kinematics and normal forces. Stall vortices occupied approximately two-thirds of the aerodynamically active blade span and persisted for nearly one-fourth of the blade rotation cycle. Stall vortex convection varied dramatically along the blade radius, yielding pronounced dynamic stall vortex deformation. Analysis of these data revealed systematic alterations to vortex kinematics due to changes in test section speed, yaw error, and blade span location.

scholarly journals Aerodynamic Analysis and Performance Prediction of VAWT and HAWT Using CARDAAV and Qblade Computer Codes

2021 ◽  
Author(s):  
Tayeb Brahimi ◽  
Ion Paraschivoiu
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Wind Farms ◽  
Rotor Blades ◽  
Dynamic Stall ◽  
And Performance ◽  
Control Stability ◽  
Induced Velocity

Wind energy researchers have recently invited the scientific community to tackle three significant wind energy challenges to transform wind power into one of the more substantial, low-cost energy sources. The first challenge is to understand the physics behind wind energy resources better. The second challenge is to study and investigate the aerodynamics, structural, and dynamics of large-scale wind turbine machines. The third challenge is to enhance grid integration, network stability, and optimization. This chapter book attempts to tackle the second challenge by detailing the physics and mathematical modeling of wind turbine aerodynamic loads and the performance of horizontal and vertical axis wind turbines (HAWT & VAWT). This work underlines success in the development of the aerodynamic codes CARDAAV and Qbalde, with a focus on Blade Element Method (BEM) for studying the aerodynamic of wind turbines rotor blades, calculating the induced velocity fields, the aerodynamic normal and tangential forces, and the generated power as a function of a tip speed ration including dynamic stall and atmospheric turbulence. The codes have been successfully applied in HAWT and VAWT machines, and results show good agreement compared to experimental data. The strength of the BEM modeling lies in its simplicity and ability to include secondary effects and dynamic stall phenomena and require less computer time than vortex or CFD models. More work is now needed for the simulation of wind farms, the influence of the wake, the atmospheric wind flow, the structure and dynamics of large-scale machines, and the enhancement of energy capture, control, stability, optimization, and reliability.

Development and Validation of a CFD Technique for the Aerodynamic Analysis of HAWT

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
S. Gómez-Iradi ◽  
R. Steijl ◽  
G. N. Barakos
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Wind Tunnel Test ◽  
Unsteady Aerodynamics ◽  
Tunnel Wall ◽  
Local Flow ◽  
Flow Angle ◽  
Thrust And Torque

This paper demonstrates the potential of a compressible Navier–Stokes CFD method for the analysis of horizontal axis wind turbines. The method was first validated against experimental data of the NREL/NASA-Ames Phase VI (Hand, et al., 2001, “Unsteady Aerodynamics Experiment Phase, VI: Wind Tunnel Test Configurations and Available Data Campaigns,” NREL, Technical Report No. TP-500-29955) wind-tunnel campaign at 7 m/s, 10 m/s, and 20 m/s freestreams for a nonyawed isolated rotor. Comparisons are shown for the surface pressure distributions at several stations along the blades as well as for the integrated thrust and torque values. In addition, a comparison between measurements and CFD results is shown for the local flow angle at several stations ahead of the wind turbine blades. For attached and moderately stalled flow conditions the thrust and torque predictions are fair, though improvements in the stalled flow regime are necessary to avoid overprediction of torque. Subsequently, the wind-tunnel wall effects on the blade aerodynamics, as well as the blade/tower interaction, were investigated. The selected case corresponded to 7 m/s up-wind wind turbine at 0 deg of yaw angle and a rotational speed of 72 rpm. The obtained results suggest that the present method can cope well with the flows encountered around wind turbines providing useful results for their aerodynamic performance and revealing flow details near and off the blades and tower.

Dynamic Stall Modeling for the Conditions of Vertical Axis Wind Turbines

AIAA Journal ◽  
2014 ◽  
Vol 52 (1) ◽  
pp. 72-81 ◽  
Author(s):  
Eduard Dyachuk ◽  
Anders Goude ◽  
Hans Bernhoff
Keyword(s):  
Wind Turbines ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Vertical Axis Wind Turbines
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