The Impact of Different Inflow Conditions on the Wake of Horizontal Axis Wind Turbine

The reliance on Computational Fluid Dynamics (CFD) simulations has drastically increased over time to evaluate the aerodynamic performance of small-scale wind turbines. With the rapid variability in customer demand, industrial requirements, economic constraints, and time limitations associated with the design and development of small-scale wind turbines, the trade-off between computational resources and the simulation’s numerical accuracy may vary significantly. In the context of wind turbine design and analysis, high fidelity simulation under full geometric and numerical complexity is more accurate but pose significant demands from a computational standpoint. There is a need to understand and quantify performance deterioration of high fidelity simulations under reduced geometric or numerical approximation on a single small scale turbine model. In the present work, the flow past a small-scale Horizontal Axis Wind Turbine (HAWT) was simulated under various geometric and numerical configurations. The geometric complexity was varied based on stationary and rotating turbine conditions. In the stationary case, simple 2D airfoil, 2.5D blade, 3D blade sections are evaluated, while rotational effects are introduced for the configuration 3D blade, rotor only, and the full-scale wind turbine with and without the inclusion of a nacelle and tower. In terms of numerical complexity, the Single Reference Frame (SRF), Multiple Reference Frames (MRF), and the Sliding Meshing Interface (SMI) is analyzed over Tip Speed Ratios (TSR) of 3, 6, 10. The quantification of aerodynamic coefficients of the blade (Cl, Cd) and turbine (Cp, Ct) was conducted along with the discussion on wake patterns in comparison with experimental data.

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Influence of the Heights of Low-Level Jets on Power and Aerodynamic Loads of a Horizontal Axis Wind Turbine Rotor

Atmosphere ◽

10.3390/atmos10030132 ◽

2019 ◽

Vol 10 (3) ◽

pp. 132 ◽

Cited By ~ 1

Author(s):

Xuyao Zhang ◽

Congxin Yang ◽

Shoutu Li

Keyword(s):

Wind Speed ◽

Power Spectrum ◽

Wind Turbine ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Aerodynamic Loads ◽

Low Level ◽

Low Level Jets ◽

Inflow Conditions ◽

Swept Area

The influence of the heights of low-level jets (LLJs) on the rotor power and aerodynamic loads of a horizontal axis wind turbine were investigated using the fatigue, aerodynamics, structures, and turbulence code. The LLJ and shear inflow wind fields were generated using an existing wind speed spectral model. We found that the rotor power predicted by the average wind speed of the hub height is higher than the actual power in relatively weak and shallow LLJ inflow conditions, especially when the LLJ height is located inside the rotor-swept area. In terms of aerodynamic loads, when the LLJ height is located inside the rotor-swept area, the root mean square (RMS) rotor thrust coefficient and torque coefficient increase, while the RMS rotor unbalanced aerodynamic load coefficients, including lateral force, longitudinal force, tilt moment, and yaw moment, decreased. This means that the presence of both positive and negative wind shear in the rotor-swept area not only increases the rotor power but also reduces the unbalanced aerodynamic loads, which is beneficial to the operation of wind turbine. Power spectrum analysis shows no obvious difference in the power spectrum characteristics of the rotor torque and thrust in LLJ inflow conditions with different heights.

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Description and Computer Modeling of a Ball-and-Socket Hub That Enables Teetering for Three-Bladed Wind Turbines

Journal of Solar Energy Engineering ◽

10.1115/1.4029813 ◽

2015 ◽

Vol 137 (3) ◽

Author(s):

Arnold Ramsland

Keyword(s):

Wind Turbine ◽

Computer Modeling ◽

Horizontal Axis ◽

Main Shaft ◽

Horizontal Axis Wind Turbine ◽

Out Of Plane ◽

Cyclic Variations ◽

Bending Loads ◽

Rainflow Counting ◽

The Impact

A horizontal axis wind turbine with a ball-and-socket hub is disclosed. The hub enables horizontal axis turbines with two or more blades to teeter in response to wind shear gradients. Computer modeling was done using existing and modified fast code in order to compare the new hub design with existing designs. Results show that a three-bladed turbine with the ball-and-socket hub provides very significant reductions in out-of-plane bending loads applied to the main shaft in comparison to a three-bladed turbine with a rigid hub. Results also show that the new hub design provides significant reductions in the out-of-plane loads applied to the blades. A blade fatigue study using a rainflow counting of multi-axial torque contributions at the blade root was performed in order to assess the impact of these reductions, and results show that the three-bladed turbine equipped with a ball-and-socket, teetering hub provides for very significant reductions in lifetime blade damage in comparison to existing wind turbine designs due to a combination of factors. The first factor is that teetering largely eliminates the cyclic variations in out-of-plane torque on the blades that are observed with rigid hubs. Here, the fatigue study shows that the three-bladed wind turbine with a teetering hub provides for an approximate sixfold reduction in lifetime blade damage in comparison to a three-bladed turbine with a rigid hub. The second factor is that the addition of a third blade reduces the load on each blade by one-third. Here, the fatigue study shows that a three-bladed turbine with a teetering hub provides for an approximate fourfold reduction in lifetime blade damage in comparison to a two-bladed turbine with a teetering hub.

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Effects of Inflow Conditions on Aerodynamic Transient Characteristics with Pitch Control of Horizontal Axis Wind Turbine

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2018.j0510304 ◽

2018 ◽

Vol 2018 (0) ◽

pp. J0510304

Author(s):

Shinya Otsuka ◽

Yutaka HASEGAWA ◽

Tatsuo USHIZIMA

Keyword(s):

Wind Turbine ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Transient Characteristics ◽

Pitch Control ◽

Inflow Conditions

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Flapwise and Edgewise Blade Loads Analysis of HAWT Rotor by Using Fluid-Oscillation Coupled Calculation Model

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-07001 ◽

2011 ◽

Author(s):

Yutaka Hasegawa ◽

Yusuke Takagi ◽

Junsuke Murata ◽

Koji Kikuyama

Keyword(s):

Wind Turbine ◽

Rotor Blade ◽

Calculation Model ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Aerodynamic Loads ◽

Coupled Calculation ◽

Fluid Oscillation ◽

Fatigue Loads ◽

Inflow Conditions

A horizontal axis wind turbine suffers fluctuating aerodynamic loads, which result in oscillations of the rotor blades. Since the blade oscillation has considerable effects on the blade fatigue life, the influence on the fatigue loads from the interaction between the aerodynamic loads and the structural oscillations should be considered in the design process of the wind turbine rotor. The objective of this work is to analyze the aerodynamic effects on the fatigue loads of rotor blade due to structural oscillation and inflow conditions, by using numerical calculation method. This paper explains a calculation model which can estimate the aerodynamic loads on the rotor blade of the horizontal axis wind turbine in the inflow conditions with the turbulence and yawed misalignment. The fluid-oscillation coupled calculation has been performed for the geometry of the NREL test turbine. The calculated results are compared with the experimental results to evaluate the validity of the calculation model.

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Effect of blade pitch angle on the aerodynamic characteristics of a twisted blade horizontal axis wind turbine based on numerical simulations

International Journal of Power Electronics and Drive Systems (IJPEDS) ◽

10.11591/ijpeds.v12.i1.pp511-519 ◽

2021 ◽

Vol 12 (1) ◽

pp. 511

Author(s):

Rajendra Roul ◽

Awadhesh Kumar

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Angular Velocity ◽

Wind Turbine ◽

Pitch Angle ◽

Aerodynamic Characteristics ◽

Horizontal Axis ◽

Performance Parameters ◽

Horizontal Axis Wind Turbine ◽

The Impact

The present work includes a study of the impact of varying pitch angles and angular velocity on the performance parameters of a horizontal axis wind turbine using computational fluid dynamics. Simulations have been made using commercial Ansys 15 software. Seven pitch angles are chosen for study, i.e., 0° , 5 ° , 10° , 15° , 20° , 25° , and 28°, and two angular velocity values of 1.57 rad/sec and 2.22 rad/sec are used for simulation. The turbulence model used is shear stress transport (SST) K-ω. A detailed study of the influence of pitch angle on the aerodynamic characteristics of the wind turbine is highlighted. Performance parameters like torque and power have been found to exhibit random variability with a change in wind velocity and pitch angle. The verification of computational fluid dynamics (CFD) with the standard empirical formula is highlighted. The best pitch angle is noted for the best power coefficient.

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Life Cycle Assessment of 2.0 MW Horizontal Axis Wind Turbine for Sustainability Analysis

Engineering Proceedings ◽

10.3390/engproc2021012060 ◽

2022 ◽

Vol 12 (1) ◽

pp. 60

Author(s):

Rabia Hassan ◽

Muhammad Mahboob ◽

Zubair Ahmed Jan ◽

Muhammad Ashiq

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Wind Turbine ◽

Energy System ◽

Horizontal Axis ◽

Horizontal Axis Wind Turbine ◽

Greenhouse Gasses ◽

Horizontal Axis Wind Turbines ◽

The Impact ◽

Primary Materials

The world is increasingly experiencing unanticipated catastrophic events because of the impact of greenhouse gasses. The two major issues with the conventional energy system are unsustainability and global warming, which are extremely harmful for the climate. The core objective of this study is a compilation of the findings related to a life cycle assessment of horizontal axis wind turbines in regard to sustainable development. Sustainability aspects and concerns have been studied and reported in terms of the life cycle of wind energy technology. This article focused on energy consumed during the life of the 2.0 MW wind turbine, mostly in the production of primary materials, processes, and maintenance-related transport phase. The turbine’s overall energy produced 1,750,000 kWh throughout a 20-year life. Over a 20year lifespan, the overall energy produced by the turbine is approximately 32% more than the energy needed to construct, and the destination for the turbine materials is a landfill at the end of the turbine’s life. For a 40% wind turbine power ratio, with the wind turbine materials delivered to landfill at the end of the turbine’s life, the electricity payback period is around 10 months, and for recycled materials it is 6 months. The comparison is also done for the wind turbine materials which are sent to landfill with and without recycling.

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

Journal of Solar Energy Engineering ◽

10.1115/1.1408307 ◽

2001 ◽

Vol 123 (4) ◽

pp. 272-281 ◽

Cited By ~ 33

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.

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