Modeling and Design Method for an Adaptive Wind Turbine Blade With Out-of-Plane Twist

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Energy Production ◽  
Full Range ◽  
Unsteady Aerodynamics ◽  
Wind Turbine Blade ◽  
Torsional Stiffness ◽  
Angle Distribution ◽  
Modeling Framework ◽  
Out Of Plane

A modeling framework to analyze a wind turbine blade subjected to an out-of-plane transformation is presented. The framework combines aerodynamic and mechanical models to support an automated design process. The former combines the National Renewable Energy Lab (NREL) aerodyn software with a genetic algorithm solver. It defines the theoretical twist angle distribution (TAD) as a function of wind speed. The procedure is repeated for a series of points that form a discrete range of wind speeds. This step establishes the full range of blade transformations. The associated theoretical TAD geometry is subsequently passed to the mechanical model. It creates the TAD geometry in the context of a novel wind turbine blade concept. The blade sections are assumed to be made by additive manufacturing, which enables tunable stiffness. An optimization problem minimizes the difference between the practical and theoretical TAD over the full range of transformations. It does so by selecting the actuator locations and the torsional stiffness ratios of consecutive segments. In the final step, the blade free shape (undeformed position) is found. The model and design support out-of-plane twisting, which can increase energy production and mitigate fatigue loads. The proposed framework is demonstrated through a case study based on energy production. It employs data acquired from the NREL Unsteady Aerodynamics Experiment. A set of blade transformations required to improve the efficiency of a fixed-speed system is examined. The results show up to 3.7% and 2.9% increases in the efficiency at cut-in and rated speeds, respectively.

A Design Methodology for a Flexible Wind Turbine Blade With an Actively Variable Twist Distribution to Increase Region 2 Efficiency

2017 ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Twist Angle ◽  
Full Range ◽  
Wind Turbine Blade ◽  
Design Solution ◽  
Angle Distribution ◽  
Design Algorithm ◽  
Aerodynamic Efficiency

This paper presents a methodology for designing key features of a flexible wind turbine blade with an actively variable twist distribution. Simulation results suggest this capability can increase the aerodynamic efficiency during Region 2 operation. The concept for the flexible blade consists of a rigid spar with flexible modular segments that form the surrounding shells. The segments are additively manufactured. The associated compliances of the each individual segment and actuator placement determine the Twist Angle Distribution (TAD). It is assumed that the degree of flexibility for each segment will be established through the design and additive manufacturing (AM) processes. Moreover, the variations in compliance make it possible for the blade to conform to the desired set of TAD geometries. The design process first determines the TAD that maximizes the aerodynamic efficiency for discrete points of wind speed in Region 2. The results are obtained using the National Renewable Energy Laboratory (NREL) Aerodyn software and a genetic algorithm. The TAD geometry is then passed to a mechanical design algorithm that locates a series of actuators and defines the stiffness ratio between the blade segments. The process employs a computer cluster to create the TAD for a set of design scenarios. The design selections are found through an objective function. It minimizes the amount of deviation between the actual TAD and that found in the aerodynamic analysis. The free-shape TAD is determined in the final step. The geometry is chosen to minimize the amount of deflection needed to shape the TAD, which changes with Region 2 wind speed. A case study suggests that a blade with only five actuators can achieve the full range of TAD geometry. Moreover, the design solution can increase the efficiency at cut-in and rated speeds up to 3.8% and 3.3%, respectively.

Machine Learning Aided Prediction of Rain Erosion Damage on Wind Turbine Blade Sections

2021 ◽  
Author(s):  
Alessio Castorrini ◽  
Paolo Venturini ◽  
Fabrizio Gerboni ◽  
Alessandro Corsini ◽  
Franco Rispoli
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Energy Production ◽  
Turbine Blades ◽  
Wind Farms ◽  
Wind Turbine Blade ◽  
Wind Turbine Blades ◽  
Coating Materials ◽  
Erosion Modelling ◽  
Rain Erosion

Abstract Rain erosion of wind turbine blades represents an interesting topic of study due to its non-negligible impact on annual energy production of the wind farms installed in rainy sites. A considerable amount of recent research works has been oriented to this subject, proposing rain erosion modelling, performance losses prediction, structural issues studies, etc. This work aims to present a new method to predict the damage on a wind turbine blade. The method is applied here to study the effect of different rain conditions and blade coating materials, on the damage produced by the rain over a representative section of a reference 5MW turbine blade operating in normal turbulence wind conditions.

Control Framework and Integrative Design Method for an Adaptive Wind Turbine Blade

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Design Method ◽  
Design Procedure ◽  
Wind Turbine Blade ◽  
Control Technique ◽  
Angle Distribution ◽  
Control Framework ◽  
Integrative Design

Abstract A control framework and integrative design method for an adaptive wind turbine blade is presented. The blade is adapted by actively transforming the twist angle distribution (TAD) along the blade. This can alleviate fatigue loads and improve wind capture. In this paper, we focus on wind capture. The proposed design concept consists of a rigid spar that is surrounded by a series of flexible blade sections. Each section has two zones of stiffness. The sections are actuated at each end to deform the TAD. A quasi-static control technique is proposed for the TAD. The controller sets the position of the blade actuators that shape the TAD during steady-state operation. A design procedure is used to define the required TAD as a function of the wind speed. This is based on an optimization procedure that minimizes the deviation between the actual TAD and that found in the aerodynamic design. The design inputs for this optimization problem include the stiffness for each zone of the section, and the actuator locations along the blade. Given the optimal TAD at each wind speed, the free position of the blade is established using a dynamic programming technique. The position is selected based on minimal actuation energy according to wind conditions at any installation site. The proposed framework is demonstrated using a National Renewable Energy Laboratory (NREL) certified wind turbine model with recorded wind data. An increase in efficiency of 3.8% with only a deviation of 0.34% from the aerodynamic TAD is observed.

A Flexible Wind Turbine Blade With an Actively Variable Twist Distribution to Increase Region 2 Efficiency: Design and Control

2017 ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Design Solution ◽  
Angle Distribution ◽  
Stiffness Ratio ◽  
Aerodynamic Efficiency ◽  
Simulation Results ◽  
And Control

A method for designing and controlling a novel wind turbine blade is presented. The blade is modular, flexible, and additively manufactured. Conventional blades are monolithic and relatively stiff. The conventional method for improving aerodynamic efficiency is through generator torque control. The anisotropic nature of the additive manufacturing (AM) process has the potential to create a flexible blade with a low torsional-to-longitudinal-stiffness ratio. This enables new design and control capabilities that could be applied to the twist angle distribution (TAD). Simulation results suggest this can increase the aerodynamic efficiency during Region 2 operation. The suggested blade design includes a rigid spar with flexible AM segments that form the surrounding shells. The stiffness of each individual segment and the actuator placement define the TAD. In practice, the degree of flexibility for each segment will be established through the design and AM processes. These variations in compliance allow the blade to conform to the desired set of TAD geometries. The proposed design process first determines the TAD that maximizes the aerodynamic efficiency in Region 2. A mechanical design algorithm subsequently locates a series of actuators and defines the stiffness ratio between the blade segments. The procedure is optimized to minimize the amount of variation between the theoretical TAD and that which is obtained in practice. The free-shape TAD is also determined in the final design step. The geometry is chosen to minimize the amount of deflection needed to shape the TAD as it changes with Region 2 wind speed. A control framework is also developed to set the TAD in relation to wind speed. A case study demonstrates the capability of the proposed method. The simulation results suggest that a TAD controlled through five actuators can achieve the full range of required motion. Moreover, the design solution can increase the efficiency at cut-in and rated speeds up to 3.8% and 3.3%, respectively.

Complex Modal Analysis of Non-Modally Damped Wind Turbine Blade

2015 ◽  
Author(s):  
Xing Xing ◽  
Brian F. Feeny
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Original System ◽  
Wind Turbine Blade ◽  
Modal Damping ◽  
Complex Modes ◽  
Aeroelastic Model ◽  
Vibration Model ◽  
Out Of Plane ◽  
Effects Of Rotation

The vibration model of a wind turbine blade can be approximated as a rotating pretwisted nonsymmetric beam, with damping and gravitational and aeroelastic loading. In this work, the out-of-plane (flapwise) and in-plane (edgewise) motion are examined with simple aeroelastic damping effects. The aeroelastic model used is based on a simple quasisteady blade-element airfoil theory. The linear velocity dependent terms are isolated and incorporated into the damping, which then turns out to be generally non modal (non Caughey). The complex modes are analyzed while neglecting the effects of rotation to single out the effect that aerodynamic damping may have on the modes. The analysis is done by first discretizing the system with assumed modes, and then solving an eigenvalue problem for the state-variable description of the discretized system. The eigen modes are recombined with the assumed mode functions to approximate the modes in the original system. The analysis is performed on the National Renewable Energy Laboratory (NREL) 23-meter blade, the NREL 63-meter blade, and the Sandia 100-meter blade. The effects of nonproportional damping are seen to become more significant as the blade size increases. The results provide some experience for the validity of making modal damping assumptions in blade analyses.

Multi-axial large-scale testing of a 34 m wind turbine blade section to evaluate out-of-plane deformations of double-curved trailing edge sandwich panels within the transition zone

2020 ◽  
pp. 0309524X2097840
Author(s):  
Jacob P Waldbjørn ◽  
Andrei Buliga ◽  
Christian Berggreen ◽  
Find Moelholt Jensen
Keyword(s):  
Wind Turbine ◽  
Transition Zone ◽  
Turbine Blade ◽  
Plane Deformation ◽  
Wind Turbine Blade ◽  
Transverse Cracks ◽  
Trailing Edge ◽  
Root Section ◽  
Out Of Plane ◽  
Plane Deformations

Transverse cracks in the double curved trailing edge panels within the transition zone are among one of the increasingly encountered in-field damages found on wind turbine blades today. Believed to be root cause of these transverse cracks, are the out-of-plane deformation of the double curved trailing edge pressure side panels. These deformations are evaluated on the inner 15 m section of a 34 m wind turbine blade – referred to here as the root section. Through a parametrical study the free end of the root section is loaded in the quasi-static regime comprising edgewise loading (Fy) and torsional moment (Mz) around the longitudinal axis of the blade. The root section is through a multi-scale numerical analysis found to exhibit representative structural behavior in terms of out-of-plane deformations within the area of interest. A combination between Fy and Mz are found to generate the highest peak-to-peak out-of-plane deformation of 15.9 mm.

Integrative Control and Design Framework for an Actively Variable Twist Wind Turbine Blade to Increase Efficiency

2018 ◽  
Author(s):  
Hamid Khakpour Nejadkhaki ◽  
John F. Hall
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Mechanical Design ◽  
Wind Turbine Blade ◽  
Angle Distribution ◽  
Stiffness Ratio ◽  
Aerodynamic Efficiency ◽  
And Control ◽  
Actuator Placement

A methodology for the design and control of a variable twist wind turbine blade is presented. The blade is, modular, flexible, and additively manufactured (AM). The AM capabilities have the potential to create a flexible blade with a low torsional-to-longitudinal-stiffness ratio. This enables new design and control capabilities that could be applied to the twist angle distribution. The variable twist distribution can increase the aerodynamic efficiency during Region 2 operation. The suggested blade design includes a rigid spar and flexible AM segments that form the surrounding shells. The stiffness of each segment and the actuator placement define the twist distribution. These values are used to find the optimum free shape for the blade. Given the optimum twist distributions, actuator placement, and free shape, the required amount of actuation could be determined. The proposed design process first determines the twist distribution that maximizes the aerodynamic efficiency in Region 2. A mechanical design algorithm subsequently locates a series of actuators and defines the stiffness ratio between the blade segments. The free shape twist distribution is selected in the next step. It is chosen to minimize the amount of actuation energy required to shape the twist distribution as it changes with Region 2 wind speed. Wind profiles of 20 different sites, gathered over a three-year period, are used to get the free shape. A control framework is then developed to set the twist distribution in relation to wind speed. A case study is performed to demonstrate the suggested procedure. The aerodynamic results show up to 3.8 and 3.3% increase in the efficiency at cut-in and rated speeds, respectively. The cumulative produced energy within three years, improved by up to 1.7%. The mechanical design suggests that the required twist distribution could be achieved by five actuators. Finally, the optimum free shape is selected based on the simulations for the studied sites.

scholarly journals Flutter Analysis of Piezoelectric Material Based Smart Wind Turbine Blade

2021 ◽  
Vol 26 (3) ◽  
pp. 240-247
Author(s):  
Hao Wang ◽  
Junyu Yi ◽  
Wei Chen ◽  
Zhexin Zhou
Keyword(s):  
Wind Turbine ◽  
Piezoelectric Material ◽  
Critical Velocity ◽  
Turbine Blade ◽  
Unsteady Aerodynamics ◽  
Wind Turbine Blade ◽  
Mass Ratio ◽  
Electrical Load ◽  
Flutter Analysis ◽  
Simulation Results

This paper presents a smart wind turbine blade of piezoelectric material. Based on Theodorsen unsteady aerodynamics and the V-g method, the flutter analysis in frequency domain is carried out for the smart wind turbine blade and the ordinary wind turbine blade. The simulation results demonstrate that the flutter critical velocity, that is, the reduced velocity of the smart wind turbine blade, is obviously much higher than that of the ordinary wind turbine blade. The smart wind turbine blade of piezoelectric material can effectively restrain the flutter of the wind turbine blade, especially for the flap motion. For the torsion motion, the smart wind turbine blade is kept away from the critical flutter. Then, to investigate the influences of different parameters on the flutter of the smart wind turbine blade, the influences of the center of gravity, the frequency ratio and the mass ratio of the blades on the flutter critical velocity of the smart wind turbine blade are researched respectively. The increase of the applied external electrical load of the piezoelectric material can increase the flutter critical velocity of the smart wind turbine blade.

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