Simulations of Unsteady Aerodynamic Effects on Innovative Wind Turbine Concepts

2016 ◽  
pp. 529-543 ◽  
Author(s):  
Annette Fischer ◽  
Levin Klein ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
Unsteady Aerodynamic

Unsteady aerodynamic modeling and control of the wind turbine with trailing edge flap

2018 ◽  
Vol 10 (6) ◽  
pp. 063304 ◽  
Author(s):  
Wenguang Zhang ◽  
Yifeng Wang ◽  
Ruijie Liu ◽  
Haipeng Liu ◽  
Xu Zhang
Keyword(s):  
Wind Turbine ◽  
Trailing Edge ◽  
Modeling And Control ◽  
Aerodynamic Modeling ◽  
Unsteady Aerodynamic ◽  
Trailing Edge Flap ◽  
And Control

scholarly journals Numerical Validation of Floating Offshore Wind Turbine Scaled Rotors for Surge Motion

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2578 ◽  
Author(s):  
Krishnamoorthi Sivalingam ◽  
Steven Martin ◽  
Abdulqadir Singapore Wala
Keyword(s):  
Wind Turbine ◽  
Turbine Rotor ◽  
Power Converter ◽  
Experimental Results ◽  
Offshore Wind ◽  
Speed Ratio ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic

Aerodynamic performance of a floating offshore wind turbine (FOWT) is significantly influenced by platform surging motions. Accurate prediction of the unsteady aerodynamic loads is imperative for determining the fatigue life, ultimate loads on key components such as FOWT rotor blades, gearbox and power converter. The current study examines the predictions of numerical codes by comparing with unsteady experimental results of a scaled floating wind turbine rotor. The influence of platform surge amplitude together with the tip speed ratio on the unsteady aerodynamic loading has been simulated through unsteady CFD. It is shown that the unsteady aerodynamic loads of FOWT are highly sensitive to the changes in frequency and amplitude of the platform motion. Also, the surging motion significantly influences the windmill operating state due to strong flow interaction between the rotating blades and generated blade-tip vortices. Almost in all frequencies and amplitudes, CFD, LR-BEM and LR-uBEM predictions of mean thrust shows a good correlation with experimental results.

Investigations of Unsteady Aerodynamics of an Offshore Floating Wind Turbine With Platform Motions Using Dual-Sliding Method

2020 ◽  
Author(s):  
Xiaodong Wang ◽  
Zhaoliang Ye ◽  
Ziwen Chen ◽  
Yize Guo ◽  
Yujun Qiao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Aerodynamic Performance ◽  
Offshore Wind ◽  
Sliding Mesh ◽  
Unsteady Aerodynamic ◽  
Floating Wind Turbine ◽  
Mesh Method ◽  
Offshore Floating Wind Turbine ◽  
Platform Motions

Abstract Offshore wind energy developed rapidly in recent years. Due to the platform motions causing by ocean waves, the aerodynamics of floating offshore wind turbines (FOWT) show strong unsteady characters than onshore wind turbines. The widely used methods to investigate the unsteady aerodynamic performance of wind turbine are Blade Element Momentum (BEM) and Free-Vortex Wake (FVW) methods. The accuracy of these two methods strongly depend on empirical formula or correction models. However, for dynamics motions of wind turbine, there is still a lack of accurate models. CFD simulations using overset or dynamic mesh methods also have been used for FOWT aerodynamic investigations. However, the mesh deforming or reconstruction methods are usually suitable for small movement of wind turbine blade. In this paper, a dual-sliding mesh method is employed to simulate the unsteady aerodynamic characters of an offshore floating wind turbine with supporting platform motions using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Both rotor rotation and platform motions are treated as rigid angular motions. The relative motion and data exchange were simulated using sliding mesh method. The NREL 5MW reference wind turbine with platform pitching and rolling motions are considered. The pitching and rolling motions of floating platform are simplified in the form of a prescribed sinusoidal function. Different conditions with two amplitudes and two frequencies of pitching and rolling motions were investigated. URANS were performed with full structured mesh for wind turbine rotor using commercial software FLUENT. The platform motions were set using User Defined Function (UDF). Transitional Shear Stress Turbulence (T-SST) model was employed. The simulation results were compared with BEM method and FVW method results. Both steady status and dynamic pitching processes are investigated. The variations of wind turbine aerodynamic load, as well as the aerodynamic character of airfoils at different spanwise positions, were obtained and analyzed in detail. The simulations results show that the platform pitching introduce remarkable influence on the wind turbine aerodynamic performance. The platform pitching has much larger influence on the wind turbine power and thrust than the platform rolling. The dual-sliding mesh method shows potentials to investigation the dynamic process with multiple rigid motions.

scholarly journals A DNN surrogate unsteady aerodynamic model for wind turbine loads calculations

2020 ◽  
Vol 1618 ◽  
pp. 052060
Author(s):  
Shreyas Ananthan ◽  
Ganesh Vijayakumar ◽  
Shashank Yellapantula
Keyword(s):  
Wind Turbine ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Model

Aerodynamic Interference Effect of Huge Wind Turbine Blades With Periodic Surge Motions Using Overset Grid-Based Computational Fluid Dynamics Approach

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Thanh Toan Tran ◽  
Dong-Hyun Kim ◽  
Ba Hieu Nguyen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Overset Grid ◽  
Wind Turbine Blades ◽  
Unsteady Aerodynamic ◽  
Rotating Blade ◽  
Floating Offshore Wind Turbines ◽  
Grid Based

The accurate prediction of unsteady aerodynamic performance and loads, for floating offshore wind turbines (FOWTs), is still questionable because several conventional methods widely used for this purpose are applied in ways that violate the theoretical assumptions of their original formulation. The major objective of the present study is to investigate the unsteady aerodynamic effects for the rotating blade due to the periodic surge motions of an FOWT. This work was conducted using several numerical approaches, particularly unsteady computational fluid dynamics (CFD) with an overset grid-based approach. The unsteady aerodynamic effects that occur when an FOWT is subjected to the surge motion of its floating support platform is assumed as a sinusoidal function. The present CFD simulation based on an overset grid approach provides a sophisticated numerical model on complex flows around the rotating blades simultaneously having the platform surge motion. In addition, an in-house unsteady blade element momentum (UBEM) and the fast (fatigue, aerodynamic, structure, and turbulence) codes are also applied as conventional approaches. The unsteady aerodynamic performances and loads of the rotating blade are shown to be changed considerably depending on the amplitude and frequency of the platform surge motion. The results for the flow interaction phenomena between the oscillating motions of the rotating wind turbine blades and the generated blade-tip vortices are presented and investigated in detail.

scholarly journals Investigations on the Unsteady Aerodynamic Characteristics of a Horizontal-Axis Wind Turbine during Dynamic Yaw Processes

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3124 ◽  
Author(s):  
Xiaodong Wang ◽  
Zhaoliang Ye ◽  
Shun Kang ◽  
Hui Hu
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Aerodynamic Characteristics ◽  
Azimuth Angle ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Structured Grid ◽  
Unsteady Aerodynamic ◽  
Yaw Angle

Wind turbines inevitably experience yawed flows, resulting in fluctuations of the angle of attack (AOA) of airfoils, which can considerably impact the aerodynamic characteristics of the turbine blades. In this paper, a horizontal-axis wind turbine (HAWT) was modeled using a structured grid with multiple blocks. Then, the aerodynamic characteristics of the wind turbine were investigated under static and dynamic yawed conditions using the Unsteady Reynolds Averaged Navier-Stokes (URANS) method. In addition, start-stop yawing rotations at two different velocities were studied. The results suggest that AOA fluctuation under yawing conditions is caused by two separate effects: blade advancing & retreating and upwind & downwind yawing. At a positive yaw angle, the blade advancing & retreating effect causes a maximum AOA at an azimuth angle of 0°. Moreover, the effect is more dominant in inboard airfoils compared to outboard airfoils. The upwind & downwind yawing effect occurs when the wind turbine experiences dynamic yawing motion. The effect increases the AOA when the blade is yawing upwind and vice versa. The phenomena become more dominant with the increase of yawing rate. The torque of the blade in the forward yawing condition is much higher than in backward yawing, owing to the reversal of the yaw velocity.

scholarly journals Unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140080 ◽  
Author(s):  
B. F. Xu ◽  
T. G. Wang ◽  
Y. Yuan ◽  
J. F. Cao
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Aerodynamic Performance ◽  
Small Scale ◽  
Floating Platform ◽  
Unsteady Aerodynamic ◽  
Blade Root ◽  
Platform Motions

A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional rotational effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip.

Design optimization of a wind turbine blade to reduce the fluctuating unsteady aerodynamic load in turbulent wind

2012 ◽  
Vol 26 (3) ◽  
pp. 827-838 ◽  
Author(s):  
Jihoon Jeong ◽  
Kyunghyun Park ◽  
Sangook Jun ◽  
Kisun Song ◽  
Dong-Ho Lee
Keyword(s):  
Wind Turbine ◽  
Design Optimization ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Aerodynamic Load ◽  
Turbulent Wind ◽  
Unsteady Aerodynamic
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