Viscous and Aeroelastic Effects on Wind Turbine Blades. The VISCEL project. Part I: 3D Navier-Stokes Rotor simulations

Wind Energy ◽  
2003 ◽  
Vol 6 (4) ◽  
pp. 365-385 ◽  
Author(s):  
P. K. Chaviaropoulos ◽  
I. G. Nikolaou ◽  
K. A. Aggelis ◽  
N. N. Soerensen ◽  
J. Johansen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Wind Turbine Blades

Analysis of Blunt Trailing Edge Airfoils

2003 ◽  
Author(s):  
K. J. Standish ◽  
C. P. van Dam
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Computational Techniques ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Large Wind ◽  
Structural Volume

The adoption of blunt trailing edge airfoils for the inner regions of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide increased structural volume, but have also been found to improve the lift characteristics of airfoils and therefore allow for section shapes with a greater maximum thickness. Limited experimental data makes it difficult for wind turbine designers to consider and conduct tradeoff studies using these section shapes. This lack of experimental data precipitated the present analysis of blunt trailing edge airfoils using computational fluid dynamics. Several computational techniques are applied including a viscous/inviscid interaction method and several Reynolds-averaged Navier-Stokes methods.

scholarly journals Detailed analysis of the blade root flow of a horizontal axis wind turbine

2016 ◽  
Vol 1 (2) ◽  
pp. 89-100 ◽  
Author(s):  
Iván Herráez ◽  
Buşra Akay ◽  
Gerard J. W. van Bussel ◽  
Joachim Peinke ◽  
Bernhard Stoevesandt
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Aerodynamic Performance ◽  
Negative Influence ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Force Coefficient ◽  
Horizontal Axis Wind Turbine ◽  
Blade Root ◽  
Root Region

Abstract. The root flow of wind turbine blades is subjected to complex physical mechanisms that influence significantly the rotor aerodynamic performance. Spanwise flows, the Himmelskamp effect, and the formation of the root vortex are examples of interrelated aerodynamic phenomena that take place in the blade root region. In this study we address those phenomena by means of particle image velocimetry (PIV) measurements and Reynolds-averaged Navier–Stokes (RANS) simulations. The numerical results obtained in this study are in very good agreement with the experiments and unveil the details of the intricate root flow. The Himmelskamp effect is shown to delay the stall onset and to enhance the lift force coefficient Cl even at moderate angles of attack. This improvement in the aerodynamic performance occurs in spite of the negative influence of the mentioned effect on the suction peak of the involved blade sections. The results also show that the vortex emanating from the spanwise position of maximum chord length rotates in the opposite direction to the root vortex, which affects the wake evolution. Furthermore, the aerodynamic losses in the root region are demonstrated to take place much more gradually than at the tip.

scholarly journals Detailed Analysis of the Blade Root Flow of a Horizontal Axis Wind Turbine

2016 ◽  
Author(s):  
I. Herráez ◽  
B. Akay ◽  
G. J. W. van Bussel ◽  
J. Peinke ◽  
B. Stoevesandt
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Force Coefficient ◽  
Horizontal Axis Wind Turbine ◽  
Physical Mechanisms ◽  
Blade Root ◽  
Root Region ◽  
Image Velocimetry

Abstract. The root flow of wind turbine blades is subjected to complex physical mechanisms that influence significantly the rotor aerodynamic performance. Spanwise flows, the Himmelskamp effect and the formation of the root vortex are examples of interrelated aerodynamic phenomena observed in the blade root region. In this study we address those phenomena by means of Particle Image Velocimetry (PIV) measurements and Reynolds Averaged Navier–Stokes (RANS) simulations. The numerical results obtained in this study are in very good agreement with the experiments and unveil the details of the intricate root flow. The Himmelskamp effect is shown to delay the stall onset and enhance the lift force coefficient Cl even at a moderate angle of attack (AoA ≈ 13°). The results also show that the vortex emanating from the spanwise position of maximum chord length rotates in the opposite direction of the root vortex, what affects the wake evolution.

Aerodynamic Analysis of Blunt Trailing Edge Airfoils

2003 ◽  
Vol 125 (4) ◽  
pp. 479-487 ◽  
Author(s):  
K. J. Standish ◽  
C. P. van Dam
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Computational Techniques ◽  
Interaction Method ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Large Wind ◽  
Structural Volume

The adoption of blunt trailing edge airfoils for the inboard region of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide a number of structural benefits, such as increased structural volume and ease of fabrication and handling, but they have also been found to improve the lift characteristics of airfoils. Therefore, the incorporation of blunt trailing edge airfoils would allow blade designers to more freely address the structural demands without having to sacrifice aerodynamic performance. Limited experimental data make it difficult for wind turbine designers to consider and conduct tradeoff studies using these section shapes and has provided the impetus for the present analysis of blunt trailing edge airfoils using computational fluid dynamics. Several computational techniques are applied, including a viscous/inviscid interaction method and three Reynolds-averaged Navier-Stokes methods.

scholarly journals 3D Multidisciplinary Automated Design Optimization Toolbox for Wind Turbine Blades

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 581
Author(s):  
Sagi Sagimbayev ◽  
Yestay Kylyshbek ◽  
Sagidolla Batay ◽  
Yong Zhao ◽  
Sai Fok ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Parametric Modeling ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Reynolds Averaged Navier Stokes ◽  
Automated Optimization ◽  
Drag Ratio

This paper presents two novel automated optimization approaches. The first one proposes a framework to optimize wind turbine blades by integrating multidisciplinary 3D parametric modeling, a physics-based optimization scheme, the Inverse Blade Element Momentum (IBEM) method, and 3D Reynolds-averaged Navier–Stokes (RANS) simulation; the second method introduces a framework combining 3D parametric modeling and an integrated goal-driven optimization together with a 4D Unsteady Reynolds-averaged Navier–Stokes (URANS) solver. In the first approach, the optimization toolbox operates concurrently with the other software packages through scripts. The automated optimization process modifies the parametric model of the blade by decreasing the twist angle and increasing the local angle of attack (AoA) across the blade at locations with lower than maximum 3D lift/drag ratio until a maximum mean lift/drag ratio for the whole blade is found. This process exploits the 3D stall delay, which is often ignored in the regular 2D BEM approach. The second approach focuses on the shape optimization of individual cross-sections where the shape near the trailing edge is adjusted to achieve high power output, using a goal-driven optimization toolbox verified by 4D URANS Computational Fluid Dynamics (CFD) simulation for the whole rotor. The results obtained from the case study indicate that (1) the 4D URANS whole rotor simulation in the second approach generates more accurate results than the 3D RANS single blade simulation with periodic boundary conditions; (2) the second approach of the framework can automatically produce the blade geometry that satisfies the optimization objective, while the first approach is less desirable as the 3D stall delay is not prominent enough to be fruitfully exploited for this particular case study.

Optimization of Flatback Airfoils for Wind Turbine Blades Using a Multi-Objective Genetic Algorithm

2012 ◽  
Author(s):  
Xiaomin Chen ◽  
Ramesh Agarwal
Keyword(s):  
Genetic Algorithm ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Multi Objective ◽  
Artificial Neural Network Ann ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Single Objective

In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. In a previous paper, ASME ES2010-90373, we employed a single objective genetic algorithm (GA) for shape optimization of flatback airfoils for generating maximum lift to drag ratio. The computational efficiency of GA was significantly enhanced with an artificial neural network (ANN). The commercially available software FLUENT was employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model. In this paper, we employ a multi-objective GA to optimize the flatback airfoils to achieve two objectives, namely the generation of maximum lift as well as the maximum lift to drag ratio. It is shown that the multi-objective GA optimization can generate superior flatback airfoils compared to those obtained by using single objective GA algorithm.

Optimization of Flatback Airfoils for Wind Turbine Blades

2010 ◽  
Author(s):  
Xiaomin Chen ◽  
Ramesh Agarwal
Keyword(s):  
Wind Turbine ◽  
Optimization Technique ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Blunt Trailing Edge ◽  
Artificial Neural Network Ann ◽  
Drag Ratio ◽  
Large Wind ◽  
Lift To Drag Ratio

In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. In this paper, we employ a genetic algorithm (GA) for shape optimization of flatback airfoils for generating maximum lift to drag ratio. The computational efficiency of GA is significantly enhanced with an artificial neural network (ANN). The commercially available software FLUENT is used for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model. It is shown that the combined GA/ANN optimization technique is capable of accurately and efficiently finding globally optimal flatback airfoils.

Investigating Three-Dimensional and Rotational Effects on Wind Turbine Blades by Means of a Quasi-3D Navier-Stokes Solver

2000 ◽  
Vol 122 (2) ◽  
pp. 330-336 ◽  
Author(s):  
P. K. Chaviaropoulos ◽  
M. O. L. Hansen
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Twist Angle ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Wind Turbine Blades ◽  
Mean Values ◽  
Power Curves

Three-dimensional and rotational viscous effects on wind turbine blades are investigated by means of a quasi-3D Navier-Stokes model. The governing equations of the model are derived from the 3-D primitive variable Navier-Stokes equations written in cylindrical coordinates in the rotating frame of reference. The latter are integrated along the radial direction and certain assumptions are made for the mean values of the radial derivatives. The validity of these assumptions is cross-checked through fully 3-D Navier-Stokes calculations. The resulting quasi-3D model suggests that three-dimensional and rotational effects be strongly related to the local chord by radii ratio and the twist angle. The equations of the model are numerically integrated by means of a pressure correction algorithm. Both laminar and turbulent flow simulations are performed. The former is used for identifying the physical mechanism associated with the 3-D and rotational effects, while the latter for establishing semiempirical correction laws for the load coefficients, based on 2-D airfoil data. Comparing calculated and measured power curves of a stall controlled wind turbine, it is shown that the suggested correction laws may improve significantly the accuracy of the predictions. [S0098-2202(00)02702-4]

scholarly journals Aerodynamic Shape Optimization of NREL S809 Airfoil for Wind Turbine Blades Using Reynolds-Averaged Navier Stokes Model—Part II

2021 ◽  
Vol 11 (5) ◽  
pp. 2211
Author(s):  
Md Tausif Akram ◽  
Man-Hoe Kim
Keyword(s):  
Wind Turbine ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Phase Iii ◽  
Navier Stokes ◽  
Wind Turbine Blades ◽  
Shape Transformation ◽  
Reynolds Averaged Navier Stokes ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Sustainability has become one of the most significant considerations in everyday work, including energy production. The fast-growing trend of wind energy around the world has increased the demand for efficient and optimized airfoils, which has paved the way for energy harvesting systems. The present manuscript proposes an aerodynamically optimized design of the well-known existing NREL S809 airfoil for performance enhancement of the blade design for wind turbines. An integrated code, based on a genetic algorithm, is developed to optimize the asymmetric NREL S809 airfoil by class shape transformation (CST) and the parametric section (PARSEC) parameterization method, analyzing its aerodynamic properties and maximizing the lift of the airfoil. The in-house MATLAB code is further incorporated with XFOIL to calculate the coefficient of lift, coefficient of drag and lift-to-drag ratio at angles of attack of 0° and 6.2° by the panel technique and validated with National Renewable Energy Laboratory (NREL) experimental results provided by The Ohio State University (OSU). On the other hand, steady-state CFD analysis is performed on an optimized S809 airfoil using the Reynolds-averaged Navier–Stokes (RANS) equation with the K–ω shear stress transport (SST) turbulent model and compared with the experimental data. The present method shows that the optimized airfoil by CST is predicted, with an increment of 11.8% and 9.6% for the lift coefficient and lift-to-drag ratio, respectively, and desirable stability parameters obtained for the design of the wind turbine blades. These characteristics significantly improve the overall aerodynamic performance of new optimized airfoils. Finally, the aerodynamically improved results are reported for the design of the NREL Phase II, Phase III and Phase VI HAWT blades.

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