scholarly journals Aerodynamic Characteristics of a Single Airfoil for Vertical Axis Wind Turbine Blades and Performance Prediction of Wind Turbines

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 257
Author(s):  
Samuel Mitchell ◽  
Iheanyichukwu Ogbonna ◽  
Konstantin Volkov
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Computational Cost ◽  
Aerodynamic Characteristics ◽  
Wind Turbine Blades ◽  
Aerodynamic Forces ◽  
Rans Model ◽  
Wide Range ◽  
Lift And Drag

The design of wind turbines requires a deep insight into their complex aerodynamics, such as dynamic stall of a single airfoil and flow vortices. The calculation of the aerodynamic forces on the wind turbine blade at different angles of attack (AOAs) is a fundamental task in the design of the blades. The accurate and efficient calculation of aerodynamic forces (lift and drag) and the prediction of stall of an airfoil are challenging tasks. Computational fluid dynamics (CFD) is able to provide a better understanding of complex flows induced by the rotation of wind turbine blades. A numerical simulation is carried out to determine the aerodynamic characteristics of a single airfoil in a wide range of conditions. Reynolds-averaged Navier–Stokes (RANS) equations and large-eddy simulation (LES) results of flow over a single NACA0012 airfoil are presented in a wide range of AOAs from low lift through stall. Due to the symmetrical nature of airfoils, and also to reduce computational cost, the RANS simulation is performed in the 2D domain. However, the 3D domain is used for the LES calculations with periodical boundary conditions in the spanwise direction. The results obtained are verified and validated against experimental and computational data from previous works. The comparisons of LES and RANS results demonstrate that the RANS model considerably overpredicts the lift and drag of the airfoil at post-stall AOAs because the RANS model is not able to reproduce vorticity diffusion and the formation of the vortex. LES calculations offer good agreement with the experimental measurements.

scholarly journals Design and Analysis of a Wind Turbine Blade with Dimples to Enhance the Efficiency through CFD with ANSYS R16.0

2018 ◽  
Vol 207 ◽  
pp. 02004
Author(s):  
M. Rajaram Narayanan ◽  
S. Nallusamy ◽  
M. Ragesh Sathiyan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Electrical Energy ◽  
Optimum Combination ◽  
Surface Topology ◽  
Wind Turbine Blades ◽  
Lift And Drag

In the global scenario, wind turbines and their aerodynamics are always subjected to constant research for increasing their efficiency which converts the abundant wind energy into usable electrical energy. In this research, an attempt is made to increase the efficiency through the changes in surface topology of wind turbines through computational fluid dynamics. Dimples on the other hand are very efficient in reducing air drag as is it evident from the reduction of drag and increase in lift in golf balls. The predominant factors influencing the efficiency of the wind turbines are lift and drag which are to be maximized and minimized respectively. In this research, surface of turbine blades are integrated with dimples of various sizes and arrangements and are analyzed using computational fluid dynamics to obtain an optimum combination. The analysis result shows that there is an increase in power with about 15% increase in efficiency. Hence, integration of dimples on the surface of wind turbine blades has helped in increasing the overall efficiency of the wind turbine.

Design and Analysis of Composite Ocean Current Turbine Blades Using NREL Codes

2012 ◽  
Author(s):  
Fang Zhou ◽  
Hassan Mahfuz ◽  
Gabriel M. Alsenas ◽  
Howard P. Hanson
Keyword(s):  
Wind Turbine ◽  
Stress Analysis ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Core Material ◽  
Ocean Current ◽  
Wind Turbine Blades ◽  
Lift And Drag ◽  
Current Turbine ◽  
Core Materials

Ocean current energy is at an early stage of development — a vital component in that is the design and analysis of turbine blades that would be used to generate the power. The ocean current turbine (OCT) is similar in function to wind turbines, capturing energy through the processes of hydrodynamic, rather than aerodynamic, lift or drag. OCT operates on many of the same principles as wind turbines and share similar design philosophies. NREL (National Renewable Energy Laboratory) has extensively investigated the design of wind turbine blades over the years and many codes have been developed. It is meaningful and prudent to take advantage of those codes and use them in the design of OCT blades. Currently available codes such as FoilCheck, PreComp, BModes, AeroDyn, FAST, etc. provides an excellent dynamic analysis of hollow composite wind turbine blades. Since OCT blades have PVC foam as core materials inside the skin, NREL codes could not be used directly. These core materials for the blade were necessary to fulfill the buoyancy requirement at ocean depth. A set of methods was therefore developed to design and analyze OCT blades where most of NREL codes could be utilized. The methods are as follows: DesignFOIL was first used to generate hydrofoil geometry (coordinates), and lift and drag coefficients for selected blade sections. FoilCheck was then used to calculate hydrofoil data for the entire range of ±180°. FoilCheck output files were later used as input for AeroDyn. In the next step, PreComp computed the section properties for the hollow composite OCT blade. Section properties of the core material such as extensional stiffness, flexural rigidity, and torsional rigidity were calculated separately and added to the properties computed by PreComp. Mode shapes and frequencies of OCT blades were computed using BModes. AeroDyn calculated the hydrodynamic lift and drag forces for the hydrofoil sections along the blade. In AeroDyn input file, kinematic viscosity, density and velocity were set to the values of seawater @ 1.05×10−6 m2/sec, 1025 kg/m3, and 1.7 m/s, respectively. Finally, FAST was used to obtain the dynamic response of three-bladed, conventional, horizontal-axis OCT. However, this analysis did not provide any stress calculations. In order to perform stress analysis, NuMAD code developed by Sandia National Laboratory was incorporated in the method. This allowed us to create ANSYS input files. Loads calculated by AeroDyn were then transported to ANSYS and a complete stress analysis was performed. Critical regions of stress concentration were identified — opening up an opportunity for materials failure and fatigue analysis. In summary, coupling of NREL codes, NuMAD, and ANSYS revealed a path way to achieve comprehensive design and analyses of OCT blades.

Single and Multi Objective CFD Optimization of Horizontal Axis Wind Turbines

2011 ◽  
Author(s):  
Fabio De Bellis ◽  
Luciano A. Catalano
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Computational Cost ◽  
Three Dimensional ◽  
Steam Turbines ◽  
Wind Turbine Blades ◽  
Multi Objective ◽  
Horizontal Axis Wind Turbines ◽  
Cfd Optimization

In spite of the enlarging interest in wind turbines development, the design optimization of wind turbine blades has not been studied in the past as gas or steam turbines optimization. Due to its reduced computational cost, Blade Element Momentum (BEM) method has been employed up to now to estimate the power output of the turbine. However, BEM method is not able to predict complex three dimensional flow fields or the performance of profiles for which drag and lift coefficients are not available. Theoretically, Computational Fluid Dynamics (CFD) can be more useful in these cases, but at the price of a much higher overall computational cost. In a past work, the authors developed and validated a simplified CFD process (including meshing) capable to assess the aerodynamic loads acting on a wind turbine with acceptable computational resources. Starting from that, in this work a full 3D CFD optimization of a small wind turbine is presented, both with constrained single- and multi-objective. Twist and chord distributions of a single blade have been varied keeping fixed the aerodynamic profile, and the obtained optimums have been compared with a benchmark case. The results demonstrate that CFD optimization can be effectively employed in a wind turbine optimization. As expected, stalled conditions of the blade are more likely to be improved than those characterized by attached flow. Future works will focus on multi-disciplinary optimization and will include also aerodynamic profile variation.

scholarly journals Novel Application and Validation of a Method to Assess Visual Impacts of Rotating Wind Turbine Blades Within Woodland Areas

2021 ◽  
Vol 89 (1) ◽  
pp. 1-14
Author(s):  
U. Nopp-Mayr ◽  
F. Kunz ◽  
F. Suppan ◽  
E. Schöll ◽  
J. Coppes
Keyword(s):  
Environmental Impact ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Power Plants ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Environmental Impact Assessments ◽  
Independent Field

AbstractIncreasing numbers of wind power plants (WPP) are constructed across the globe to reduce the anthropogenic contribution to global warming. There are, however, concerns on the effects of WPP on human health as well as related effects on wildlife. To address potential effects of WPP in environmental impact assessments, existing models accounting for shadow flickering and noise are widely applied. However, a standardized, yet simple and widely applicable proxy for the visibility of rotating wind turbines in woodland areas was largely lacking up to date. We combined land cover information of forest canopy extracted from orthophotos and airborne laser scanning (LiDAR) data to represent the visibility of rotating wind turbines in five woodland study sites with a high spatial resolution. Performing an in-situ validation in five study areas across Europe which resulted in a unique sample of 1738 independent field observations, we show that our approach adequately predicts from where rotating wind turbine blades are visible within woodlands or not. We thus provide strong evidence, that our approach yields a valuable proxy of the visibility of moving rotor blades with high resolution which in turn can be applied in environmental impact assessments of WPP within woodlands worldwide.

scholarly journals Sustainable End-of-Life Management of Wind Turbine Blades: Overview of Current and Coming Solutions

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1124
Author(s):  
Leon Mishnaevsky Mishnaevsky
Keyword(s):  
Wind Turbine ◽  
End Of Life ◽  
Wind Turbines ◽  
Natural Fiber ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Maintenance And Repair ◽  
Life Management ◽  
Large Wind

Various scenarios of end-of-life management of wind turbine blades are reviewed. “Reactive” strategies, designed to deal with already available, ageing turbines, installed in the 2000s, are discussed, among them, maintenance and repair, reuse, refurbishment and recycling. The main results and challenges of “pro-active strategies”, designed to ensure recyclability of new generations of wind turbines, are discussed. Among the main directions, the wind turbine blades with thermoplastic and recyclable thermoset composite matrices, as well as wood, bamboo and natural fiber-based composites were reviewed. It is argued that repair and reuse of wind turbine blades, and extension of the blade life has currently a number of advantages over other approaches. While new recyclable materials have been tested in laboratories, or in some cases on small or medium blades, there are remaining technological challenges for their utilization in large wind turbine blades.

Research on Wind Turbine Blade Loads and Dynamics Factors

2014 ◽  
Vol 1014 ◽  
pp. 124-127
Author(s):  
Zhi Qiang Xu ◽  
Jian Huang
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbines ◽  
Mechanical Energy ◽  
Turbine Blades ◽  
Electrical Energy ◽  
Wind Turbine Blade ◽  
Strength Analysis ◽  
Wind Turbine Blades ◽  
Turbine Wheel

Wind turbines consists of three key parts, namely, wind wheels (including blades, hub, etc.), cabin (including gearboxes, motors, controls, etc.) and the tower and Foundation. Wind turbine wheel is the most important part ,which is made up of blades and hubs. Blade has a good aerodynamic shape, which will produce aerodynamic in the airflow rotation, converting wind energy into mechanical energy, and then, driving the generator into electrical energy by gearbox pace. Wind turbine operates in the natural environment, their load wind turbine blades are more complex. Therefore load calculations and strength analysis for wind turbine design is very important. Wind turbine blades are core components of wind turbines, so understanding of their loads and dynamics by which the load on the wind turbine blade design is of great significance.

scholarly journals FSI in Wind Turbines: A Review

2020 ◽  
Vol 8 (3) ◽  
pp. 37
Author(s):  
Yogesh Ramesh Patel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Arbitrary Lagrangian Eulerian ◽  
Wind Turbine Blades ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Deformable Structure

This paper provides a brief overview of the research in the field of Fluid-structure interaction in Wind Turbines. Fluid-Structure Interaction (FSI) is the interplay of some movable or deformable structure with an internal or surrounding fluid flow. Flow brought about vibrations of two airfoils used in wind turbine blades are investigated by using a strong coupled fluid shape interplay approach. The approach is based totally on a regularly occurring Computational Fluid Dynamics (CFD) code that solves the Navier-Stokes equations defined in Arbitrary Lagrangian-Eulerian (ALE) coordinates by way of a finite extent method. The need for the FSI in the wind Turbine system is studied and comprehensively presented.

A Review of Wind Turbine Polar Data and its Effect on Fatigue Loads Simulation Accuracy

2015 ◽  
Author(s):  
Matthew Lennie ◽  
Georgios Pechlivanoglou ◽  
David Marten ◽  
Christian Navid Nayeri ◽  
Oliver Paschereit
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Leading Edge ◽  
Sensitivity Study ◽  
Wind Turbine Blades ◽  
Simulation Code ◽  
Simulation Accuracy ◽  
Inflow Turbulence ◽  
Lift And Drag

To certify a Wind Turbine the standard processes set out by the GL guidelines and the IEC61400 demand a large number of simulations in order to justify the safe operation of the machine in all reasonably probable scenarios. The result of this rather demanding process is that the simulations rely on lower fidelity methods such as the Blade Element Momentum (BEM) method. The BEM method relies on a number of simplified inputs including the coefficient of lift and drag polar data (usually referred to as polars). These polars are usually either measured experimentally, generated using tools such as XFoil or, in some cases obtained using 2D CFD. It is typical to then modify these polars in order to make them suitable for aeroelastic simulations. Some of these modifications include 360° angle of attack extrapolation methods and polar modifications to account for 3D effects. Many of these modifications can be perceived to be a black art due to the manual selection of coefficients. The polars can misrepresent reality for many reasons, for example, inflow turbulence can affect measurements obtained in wind tunnels. Furthermore, on real wind turbine blades leading edge erosion can reduce performance. Simulated polars can even vary significantly due to the choice of turbulence models. Stack these effects on top of the uncertainties caused by yaw error, pitch error and dynamic stall and one can clearly see an operating environment hostile to accurate simulations. Colloquial evidence suggests that experienced designers would account for all of these sources of errors methodically, however, this is not reflected by the certification process. A review of experimental data and literature was performed to identify some of the inaccuracies in wind turbine polars. Significant variations were found between a range of 2D polar techniques and wind tunnel measurements. A sensitivity study was conducted using the aeroelastic simulation code FAST (National Renewable Energy Laboratory) with lift and drag polars sourced using different methods. The results were post-processed to give comparisons the rotor blade fatigue damage; variations in accumulated damages reached levels of 164%. This variation is not disastrous but is certainly enough to motivate a new approach for certifying the aerodynamic performance of wind turbines. Such an approach would simply see the source of polar data and all post-processing steps documented and included in the checks performed by certification bodies.

Alternative Materials, Manufacturing Processes, and Structural Designs for Large Wind Turbine Blades

2002 ◽  
Author(s):  
Dayton A. Griffin
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Cost Effective ◽  
Manufacturing Processes ◽  
Wind Turbine Blades ◽  
Cost Weight ◽  
Study Results ◽  
Wide Range ◽  
Structural Configurations ◽  
Self Gravity

As part of the U.S. Department of Energy’s Wind Partnerships for Advanced Component Technologies program, Global Energy Concepts LLC (GEC) has performed a study concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. Constraints to cost-effective scaling-up of the current commercial blade designs and manufacturing methods are identified, including self-gravity loads, transportation, and environmental considerations. A trade-off study is performed to evaluate the incremental changes in blade cost, weight, and stiffness for a wide range of composite materials, fabric types, and manufacturing processes. Fiberglass/carbon hybrid blades are identified as having a promising combination of cost, weight, stiffness and fatigue resistance. Vacuum-assisted resin transfer molding, resin film infusion, and pre-impregnated materials are identified as having benefits in reduced volatile emissions, higher fiber content, and improved laminate quality relative to the baseline wet lay-up process. Alternative structural designs are identified, including jointed configurations to facilitate transportation. Based on the study results, recommendations are developed for further evaluation and testing to verify the predicted material and structural performance.

scholarly journals Bionic Design of Wind Turbine Blade Based on Long-Eared Owl’s Airfoil

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Weijun Tian ◽  
Zhen Yang ◽  
Qi Zhang ◽  
Jiyue Wang ◽  
Ming Li ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Lower Surface ◽  
Aerodynamic Characteristics ◽  
Wind Turbine Blade ◽  
Wind Turbine Blades ◽  
Bionic Design ◽  
Bionic Blade

The main purpose of this paper is to demonstrate a bionic design for the airfoil of wind turbines inspired by the morphology of Long-eared Owl’s wings. Glauert Model was adopted to design the standard blade and the bionic blade, respectively. Numerical analysis method was utilized to study the aerodynamic characteristics of the airfoils as well as the blades. Results show that the bionic airfoil inspired by the airfoil at the 50% aspect ratio of the Long-eared Owl’s wing gives rise to a superior lift coefficient and stalling performance and thus can be beneficial to improving the performance of the wind turbine blade. Also, the efficiency of the bionic blade in wind turbine blades tests increases by 12% or above (up to 44%) compared to that of the standard blade. The reason lies in the bigger pressure difference between the upper and lower surface which can provide stronger lift.

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