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.

scholarly journals An Aerodynamic Method for the Preliminary Design of Horizontal Axis Wind Turbines

10.14311/18 ◽  
2000 ◽  
Vol 40 (1) ◽  
Author(s):  
X. Munduate ◽  
F. N. Coton
Keyword(s):  
Wind Turbines ◽  
Three Dimensional ◽  
Dynamic Stall ◽  
Test Case ◽  
Preliminary Design ◽  
Aerodynamic Design ◽  
Specific Test ◽  
Horizontal Axis Wind Turbines ◽  
Rotor Disk ◽  
Blade Element

The present paper describes a method developed to assist in the preliminary aerodynamic design of wind turbines by identifying regions of the rotor disk which are dominated by unsteady and/or three-dimensional effects. The technique is based on a blade element/momentum predictor that has been extended to consider yawed flow and tower shadow effects. In addition, the method tracks temporal changes in blade incidence to identify regions of the rotor disk which are susceptible to dynamic stall. It also monitors and assesses the severity of three-dimensional stall delay and the extent to which this interacts with the regions of unsteadiness. In the paper the capability of the method will be demonstrated by application to the specific test case of the U. S. National Renewable Energy Laboratories (NREL) Combined Experiment turbine.

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.

scholarly journals Methodology for the engineering calculation of flaps on Wind Turbines using BEM codes

2016 ◽  
Author(s):  
Maria Aparicio-Sanchez ◽  
Alvaro Gonzalez-Salcedp ◽  
Sugoi Gomez-Iradi ◽  
Xabier Munduate
Keyword(s):  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Engineering Calculation ◽  
Root Effect ◽  
Validation And Verification ◽  
Momentum Theory ◽  
Aerodynamic Control ◽  
Control Devices ◽  
Circulation Theory ◽  
Blade Element

Abstract. Aeroelastic codes based on Blade Element Momentum theory are the standard used by many wind turbine designers. These codes usually include models and corrections for unsteady aerodynamics, tip and root effect, tower shadow and other effects. In general, this kind of codes does not include models to adequately simulate aerodynamic control devices. This paper presents a method to take into account the unsteady contributions due to the flap motion (based on indicial models) and the spanwise effects (based on circulation theory), in order to simulate flaps on the blades. This method can be included in BEM codes in general and it could also be applied to another kind of control devices. The validation and verification show the accuracy of this method using experimental data for two-dimensional unsteady cases, and CFD for three-dimensional steady and unsteady cases.

A Computational Fluid Dynamics Analysis of Turbulence and Wakes of Horizontal Axis Wind Turbines During Non-Operational Time Periods

2020 ◽  
Author(s):  
Hussein Al-Qarishey ◽  
Robert W. Fletcher
Keyword(s):  
Wind Turbines ◽  
Unstructured Grid ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Computational Fluid Dynamics Analysis ◽  
Horizontal Axis Wind Turbines ◽  
Wind Velocities ◽  
Utility Scale ◽  
Operational Time

Abstract Wind turbines can create turbulence and downstream wakes which can introduce generation losses of downstream impacted turbines. These downstream turbine-induced losses are due to two different conditions. The first is from power-producing rotating blades of upstream wind turbines agitating the subsequent downstream wind in a cork-screw like manner. The second is from non-rotating, non-operational, non-power-generating wind turbines. These non-operating turbines may be under scheduled service shutdown, or rendered non-functional due to longer-term or permanent mechanical problems. In this work CFD was used to study downstream turbulence and wakes of a utility-scale, non-operational three-blade horizontal axis wind turbines (HAWT). A flow field was constructed using an unstructured grid around a HAWT (rotor hub elevation of 80 meters and a blade length of 40 meters). Various wind velocities were studied up to 25 meters per second. Incompressible flow was used to assess downstream turbulence using a three-dimensional steady state and unsteady state SST k-ω (two equation) turbulence model. Different blade positions with respect to angle of attack (α) were studied, with a 4 degree angle of attack reported here. Pressures and velocities for distances of 100 meters in front and 500 meters downstream from the wind turbine are reported.

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 73 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

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.

Computational Investigation of Tower Shadow Effects on Wind Turbines

2011 ◽  
Author(s):  
Adrian Sescu ◽  
Brett Andersen ◽  
Abdollah A. Afjeh
Keyword(s):  
Wind Turbines ◽  
Stokes Equations ◽  
Three Dimensions ◽  
Navier Stokes ◽  
Turbulent Regime ◽  
Navier Stokes Equations ◽  
Shadow Effect ◽  
Horizontal Axis Wind Turbines ◽  
Computational Fluid Dynamics Cfd ◽  
Tower Shadow

In this paper, a Computational Fluid Dynamics (CFD) analysis of tower shadow effect associated with downwind configuration horizontal axis wind turbines (HAWT) is presented. This work is part of a large project focused on the design and installation of a multi-megawatt, downwind configuration, offshore HAWT in Lake Erie. The numerical tool is a dedicated commercial CFD solver, capable of performing accurate simulations in three dimensions, by solving the Navier-Stokes equations in turbulent regime. The tower shadow effect is analyzed by comparing results from the downwind configuration to results from the corresponding upwind configuration and free rotor.

Implementation of Computational Methods to Obtain Accurate Induction Factors for Offshore Wind Turbines

2014 ◽  
Author(s):  
Anand Bahuguni ◽  
Krishnamoorthi Sivalingam ◽  
Peter Davies ◽  
Johan Gullman-Strand ◽  
Vinh Tan Nguyen
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Offshore Wind ◽  
Cfd Simulations ◽  
Sea State ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Blade Tip ◽  
Computational Fluid Dynamics Cfd ◽  
Blade Element

Most of the wind turbine analysis softwares widely being used in the market are based on the Blade Element Momentum method (BEM). The two important parameters that the BEM codes calculate are the axial and the tangential induction factors. These factors are calculated based on the empirical blade lift coefficient Cl and drag coefficient Cd along with some loss/correction functions to account for the losses near the blade tip and the hub. The current study focusses on verifying the values of induction factors using Computational Fluid Dynamics (CFD) simulations for floating offshore wind turbines at a selected sea state. The study includes steady state calculations as well as transient calculations for pitching motions of the turbine due to waves. The NREL FAST software is used to set the simulation scenarios according to OC3 Phase IV cases. The blades are divided a number of elements in CFD calculations and the data are extracted at individual elements to have an exact comparison with the BEM based calculations.

Blade Three-Dimensional Dynamic Stall Response to Wind Turbine Operating Condition

2003 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Wind Turbine ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Dynamic Stall ◽  
Aerodynamic Load ◽  
Load Prediction ◽  
The Cost ◽  
Turbine Design ◽  
Yaw Angle

To further reduce the cost of wind energy, future turbine designs will continue to migrate toward lighter and more flexible structures. Thus, the accuracy and reliability of aerodynamic load prediction has become a primary consideration in turbine design codes. Dynamically stalled flows routinely generated during yawed operation are powerful and potentially destructive, as well as complex and difficult to model. As a prerequisite to aerodynamics model improvements, wind turbine dynamic stall must be characterized in detail and thoroughly understood. In the current study, turbine blade surface pressure data and local inflow data acquired by the NREL Unsteady Aerodynamics Experiment during the NASA Ames wind tunnel experiment were analyzed. The dynamically stalled, vortex dominated flow field responded in systematic fashion to variations in wind speed, turbine yaw angle, and radial location, forming the basis for more thorough comprehension of wind turbine dynamic stall and improved modeling.

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