Application of a turbulent vortex core model in the free vortex wake scheme to predict wind turbine aerodynamics

2018 ◽  
Vol 10 (2) ◽  
pp. 023303 ◽  
Author(s):  
Bofeng Xu ◽  
Junheng Feng ◽  
Tongguang Wang ◽  
Yue Yuan ◽  
Zhenzhou Zhao
Keyword(s):  
Wind Turbine ◽  
Vortex Core ◽  
Core Model ◽  
Vortex Wake ◽  
Free Vortex ◽  
Turbulent Vortex ◽  
Wind Turbine Aerodynamics

Experimental Investigation on the Tip Vortex of a Wind Turbine With and Without a Slotted Tip

2017 ◽  
Author(s):  
Pengyin Liu ◽  
Jinge Chen ◽  
Shen Xin ◽  
Xiaocheng Zhu ◽  
Zhaohui Du
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Wind Turbine ◽  
Vortex Core ◽  
Control Method ◽  
Tip Vortex ◽  
Wake Flow ◽  
Core Model ◽  
Near Wake ◽  
Measured Velocity

In this paper, a slotted tip structure is experimentally analyzed. A wind turbine with three blades, of which the radius is 301.74mm, is investigated by the PIV method. Each wind turbine blade is formed with a slots system comprising four internal tube members embedded in the blade. The inlets of the internal tube member are located at the leading edge of the blade and form an inlet array. The outlets are located at the blade tip face and form an outlet array. The near wake flow field of the wind turbine with slotted tip and without slotted tip are both measured. Velocity field of near wake region and clear images of the tip vortex are captured under different wake ages. The experimental results show that the radius of the tip vortex core is enlarged by the slotted tip at any wake age compared with that of original wind turbine. Moreover, the diffusion process of the tip vortex is accelerated by the slotted tip which lead to the disappearance of the tip vortex occurs at smaller wake age. The strength of the tip vortex is also reduced indicating that the flow field in the near wake of wind turbine is improved. The experimental data are further analyzed with the vortex core model to reveal the flow mechanism of this kind of flow control method. The turbulence coefficient of the vortex core model for wind turbine is obtained from the experimental data of the wind turbine with and without slotted tip. It shows that the slotted tip increases the turbulence strength in the tip vortex core by importing airflow into the tip vortex core during its initial generation stage, which leads to the reduction of the tip vortex strength. Therefore, it is promising that the slotted tip can be used to weaken the vorticity and accelerate the diffusion of the tip vortex which would improve the problem caused by the tip vortex.

Accuracy of the aerodynamic performance of wind turbines using vortex core models in the free vortex wake method

2019 ◽  
Vol 11 (5) ◽  
pp. 053307
Author(s):  
Bofeng Xu ◽  
Bingbing Liu ◽  
Xin Cai ◽  
Yue Yuan ◽  
Zhenzhou Zhao ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Vortex Core ◽  
Aerodynamic Performance ◽  
Vortex Wake ◽  
Free Vortex

Predicting Wind Turbine Wake Breakdown Using a Free Vortex Wake Code

AIAA Journal ◽  
2020 ◽  
Vol 58 (11) ◽  
pp. 4672-4685
Author(s):  
D. Marten ◽  
C. O. Paschereit ◽  
X. Huang ◽  
M. Meinke ◽  
W. Schröder ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vortex Wake ◽  
Free Vortex ◽  
Turbine Wake ◽  
Wind Turbine Wake

Investigations on the Fatigue Load Reduction Potential of Advanced Control Strategies for Multi-MW Wind Turbines Using a Free Vortex Wake Model

2018 ◽  
Author(s):  
Sebastian Perez-Becker ◽  
Joseph Saverin ◽  
David Marten ◽  
Jörg Alber ◽  
George Pechlivanoglou ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Reduction Potential ◽  
Fatigue Loading ◽  
Vortex Wake ◽  
Load Reduction ◽  
Fatigue Load ◽  
Aerodynamic Forces ◽  
Actuation Frequency ◽  
Free Vortex ◽  
Wind Speeds

This paper presents the results of a fatigue load evaluation from aeroelastic simulations of a multi-megawatt wind turbine. Both the Blade Element Momentum (BEM) and the Lifting Line Free Vortex Wake (LLFVW) methods were used to compute the aerodynamic forces. The loads in selected turbine components, calculated from NREL’s FAST v8 using the aerodynamic solver AeroDyn, are compared to the loads obtained using the LLFVW aerodynamics formulation in QBlade. The DTU 10 MW Reference Wind Turbine is simulated in power production load cases at several wind speeds under idealized conditions. The aerodynamic forces and turbine loads are evaluated in detail, showing very good agreement between both codes. Additionally, the turbine is simulated under realistic conditions according to the current design standards. Fatigue loads derived from load calculations using both codes are compared when the turbine is controlled with a basic pitch and torque controller. It is found that the simulations performed with the BEM method generally predict higher fatigue loading in the turbine components. A higher pitch activity is also predicted with the BEM simulations. The differences are larger for wind speeds around rated wind speed. Furthermore, the fatigue reduction potential of the individual pitch control (IPC) strategy is examined and compared when using the two different codes. The IPC strategy shows a higher load reduction of the out-of-plane blade root bending moments when simulated with the LLFVW method. This is accompanied with higher pitch activity at the actuation frequency of the IPC strategy.

scholarly journals Is the Blade Element Momentum Theory overestimating Wind Turbine Loads? – A Comparison with a Lifting Line Free Vortex Wake Method

2019 ◽  
Author(s):  
Sebastian Perez-Becker ◽  
Francesco Papi ◽  
Joseph Saverin ◽  
David Marten ◽  
Alessandro Bianchini ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vortex Wake ◽  
Bending Moments ◽  
Free Vortex ◽  
Aerodynamic Loads ◽  
Blade Root ◽  
Out Of Plane ◽  
Design Loads ◽  
Lifting Line ◽  
Blade Element

Abstract. Load calculations play a key role in determining the design loads of different wind turbine components. State of the art in the industry is to use the Blade Element Momentum (BEM) theory to calculate the aerodynamic loads. Due to their simplifying assumptions of the rotor aerodynamics, BEM methods have to rely on several engineering correction models to capture the aerodynamic phenomena present in Design Load Cases (DLCs) with turbulent wind. Because of this, BEM methods can overestimate aerodynamic loads under challenging conditions when compared to higher-order aerodynamic methods - such as the Lifting Line Free Vortex Wake (LLFVW) method – leading to unnecessarily high design loads and component costs. In this paper, we give a quantitative answer to the question of BEM load overestimation by comparing the results of aeroelastic load calculations done with the BEM-based OpenFAST code and the QBlade code which uses a LLFVW method. We compare extreme and fatigue load predictions from both codes using 66 ten-minute load simulations of the DTU 10 MW Reference Wind Turbine according to the IEC 61400-1 power production DLC group. Results from both codes show differences in fatigue and extreme load estimations for practically all considered sensors of the turbine. LLFVW simulations predict 4 % and 14 % lower lifetime Damage Equivalent Loads (DELs) for the out-of-plane blade root and the tower base fore-aft bending moments, when compared to BEM simulations. The results also show that lifetime DELs for the yaw bearing tilt- and yaw moments are 2 % and 4 % higher when calculated with the LLFVW code. An ultimate state analysis shows that extreme loads of the blade root out-of-plane and the tower base fore-aft bending moments predicted by the LLFVW simulations are 3 % and 8 % lower than the moments predicted by BEM simulations, respectively. Further analysis reveals that there are two main contributors to these load differences. The first is the different treatment in both codes of the effect that sheared inflow has on the local blade aerodynamics and second is the wake memory effect model which was not included in the BEM simulations.

Aerodynamic Analysis and Optimization of Wind Turbines Based on Full Free Vortex Wake Model

2013 ◽  
Author(s):  
Xiancheng Song ◽  
Jiang Chen ◽  
Gang Du ◽  
Lucheng Ji
Keyword(s):  
Wind Turbine ◽  
Series Representation ◽  
Vortex Sheet ◽  
Vortex Wake ◽  
Thrust Coefficient ◽  
Free Vortex ◽  
Aerodynamic Analysis ◽  
Multipole Methods ◽  
Wake Model ◽  
Free Wake

The aerodynamic analysis and optimization of wind turbine based on a full free vortex wake model is presented. Instead of a simplification of the vortex wake structure, this model predict an adequate free-wake extension which can accurately take into account the profound influence of vortex sheet downstream on the aerodynamic performance of wind turbine. The problem that the model suffers from high computational costs is solved by combining the Fast Multipole Methods (FMM) for an efficient evaluation of the Biot–Savart law with the parallel processing. The model is applied to the aerodynamic analysis of wind turbine and a stable convergent numerical solution is achieved using the pseudo-implicit technique (steady) and predictor-corrector PC2B scheme (unsteady). The optimization based on this analysis is also efficiently carried out using a Fourier series representation of the bound circulation as optimization variables, using a given thrust coefficient as a constraint. The chord and twist distributions that completely define the geometry are produced from the obtained optimal bound circulation distribution. The optimization is capable of quickly finding an optimum design using a few optimization variables. The validations of presented methods are performed through comparisons with the National Renewable Energy Laboratory (NREL) wind turbine experiment.

Predicting Wind Turbine Wake Breakdown Using a Free Vortex Wake Code

2019 ◽  
Author(s):  
David Marten ◽  
Christian O. Paschereit ◽  
Xu Huang ◽  
Matthias H. Meinke ◽  
Wolfgang Schroeder ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vortex Wake ◽  
Free Vortex ◽  
Turbine Wake ◽  
Wind Turbine Wake
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