The Importance of Fully-attached Unsteady Aerodynamics in Floating Wind Turbine Design

2013 ◽  
Author(s):  
R. Proskovics ◽  
J. Feuchtwang ◽  
S. Huang
Keyword(s):  
Wind Turbine ◽  
Unsteady Aerodynamics ◽  
Floating Wind Turbine ◽  
Turbine Design

Coupled Dynamic Analysis of a Spar Type Floating Wind Turbine

2011 ◽  
Vol 346 ◽  
pp. 433-439 ◽  
Author(s):  
Liang Zhang ◽  
Hai Tao Wu ◽  
Xiao Rong Ye ◽  
Feng Mei Jing
Keyword(s):  
Wind Turbine ◽  
Time History ◽  
Coupled Analysis ◽  
Hydrodynamic Effect ◽  
Elastic Rod ◽  
Thrust Coefficient ◽  
Coupled Dynamic Analysis ◽  
Floating Wind Turbine ◽  
Fem Method ◽  
Turbine Design

Floating wind turbine is drawn great attention for deepwater wind energy, and some concepts have been proposed. Dynamic response is of great importance for design and analysis. In this paper, the validated fully coupled analysis code HARP is employed to analyze a spar type concept. The wind turbine is modeled as a wind block with certain thrust coefficient, and the hydrodynamic parameters are calculated using WAMIT. The mooring system is modeled using FEM method and analyzed based on elastic rod theory. The performance of this system is calculated in time domain including the coupled aero-hydrodynamic effect. The simulation is taken under certain design load cases, and primary characteristics are given both in time history and statistics. The results indicate that the concept has excellent performance and HARP could be an effective tool for floating wind turbine design and analysis.

Short and Long Term Extreme Reliability Analysis Applied to Floating Wind Turbine Design

2011 ◽  
Author(s):  
Timothe´e Perdrizet ◽  
Daniel Averbuch
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Energy Agency ◽  
Floating Wind Turbine ◽  
Extreme Response ◽  
Short And Long Term ◽  
Turbine Design ◽  
Wave Induced

This paper describes and exemplifies an efficient methodology to assess, jointly and in a single calculation, the short and long terms failure probabilities associated to the extreme response of a floating wind turbine, subjected to wind and wave induced loads. This method is applied to the realistic case study OC3-Hywind used in phase IV of the IEA (International Energy Agency) Annex XXIII Offshore Code Comparison Collaboration. The key point of the procedure, derived from the outcrossing approach, consists in computing the mean of the outcrossing rate of the floating wind turbine response in the failure domain over both the short term variables and the ergodic variables defining long term parameters.

Blade Three-Dimensional Dynamic Stall Response to Wind Turbine Operating Condition

2003 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Wind Turbine ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Dynamic Stall ◽  
Aerodynamic Load ◽  
Load Prediction ◽  
The Cost ◽  
Turbine Design ◽  
Yaw Angle

To further reduce the cost of wind energy, future turbine designs will continue to migrate toward lighter and more flexible structures. Thus, the accuracy and reliability of aerodynamic load prediction has become a primary consideration in turbine design codes. Dynamically stalled flows routinely generated during yawed operation are powerful and potentially destructive, as well as complex and difficult to model. As a prerequisite to aerodynamics model improvements, wind turbine dynamic stall must be characterized in detail and thoroughly understood. In the current study, turbine blade surface pressure data and local inflow data acquired by the NREL Unsteady Aerodynamics Experiment during the NASA Ames wind tunnel experiment were analyzed. The dynamically stalled, vortex dominated flow field responded in systematic fashion to variations in wind speed, turbine yaw angle, and radial location, forming the basis for more thorough comprehension of wind turbine dynamic stall and improved modeling.

The unsteady aerodynamics of floating wind turbine under platform pitch motion

2018 ◽  
Vol 232 (8) ◽  
pp. 1019-1036 ◽  
Author(s):  
Xin Shen ◽  
Ping Hu ◽  
Jinge Chen ◽  
Xiaocheng Zhu ◽  
Zhaohui Du
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Degrees Of Freedom ◽  
Unsteady Aerodynamics ◽  
Aerodynamic Performance ◽  
Floating Platform ◽  
Pitch Motion ◽  
Floating Wind Turbine ◽  
Fixed Base ◽  
Turbine Rotors

The aerodynamic performance of floating platform wind turbines is much more complex than fixed-base wind turbines because of the flexibility of the floating platform. Due to the extra six degrees-of-freedom of the floating platform, the inflow of the wind turbine rotors is highly influenced by the motions of the floating platform. It is therefore of interest to study the unsteady aerodynamics of the wind turbine rotors involved with the interaction of the floating platform induced motions. In the present work, a lifting surface method with a free wake model is developed for analysis of the unsteady aerodynamics of wind turbines. The aerodynamic performance of the NREL 5 MW floating wind turbine under the prescribed floating platform pitch motion is studied. The unsteady aerodynamic loads, the transient of wind turbine states, and the instability of the wind turbine wakes are discussed in detail.

Blade Three-Dimensional Dynamic Stall Response to Wind Turbine Operating Condition

2005 ◽  
Vol 127 (4) ◽  
pp. 488-495 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Wind Turbine ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Dynamic Stall ◽  
Aerodynamic Load ◽  
Load Prediction ◽  
The Cost ◽  
Turbine Design ◽  
Yaw Angle

To further reduce the cost of wind energy, future turbine designs will continue to migrate toward lighter and more flexible structures. Thus, the accuracy and reliability of aerodynamic load prediction has become a primary consideration in turbine design codes. Dynamically stalled flows routinely generated during yawed operation are powerful and potentially destructive, as well as complex and difficult to model. As a prerequisite to aerodynamics model improvements, wind turbine dynamic stall must be characterized in detail and thoroughly understood. The current study analyzed turbine blade surface pressure data and local inflow data acquired by the NREL Unsteady Aerodynamics Experiment during the NASA Ames wind tunnel experiment. Analyses identified and characterized two key dynamic stall processes, vortex initiation and vortex convection, across a broad parameter range. Results showed that both initiation and convection exhibited pronounced three-dimensional kinematics, which responded in systematic fashion to variations in wind speed, turbine yaw angle, and radial location.

scholarly journals UNAFLOW: a holistic experiment about the aerodynamics of floating wind turbines under imposed surge motion

2021 ◽  
Author(s):  
Alessandro Fontanella ◽  
Ilmas Bayati ◽  
Robert Mikkelsen ◽  
Marco Belloli ◽  
Alberto Zasso
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Unsteady Aerodynamics ◽  
Model Tests ◽  
Tip Vortex ◽  
Scale Model ◽  
Floating Wind Turbine ◽  
Floating Offshore Wind Turbines ◽  
Sectional Model

Abstract. Floating offshore wind turbines are subjected to large motions because of the additional degrees of freedom offered by the floating foundation. The rotor operates in highly dynamic inflow conditions and this is deemed to have a significant effect on the aerodynamic loads, as well as on the wind turbine wake. Floating wind turbines and floating farms are designed by means of numerical tools, that have to model these unsteady aerodynamic phenomena to be predictive of reality. Experiments are needed to get a deeper understanding of the unsteady aerodynamics, and hence leverage this knowledge to develop better models, as well as to produce data for the validation and calibration of the existing tools. This paper presents a wind-tunnel scale-model experiment about the unsteady aerodynamics of floating wind turbines that followed a radically different approach than the other existing experiments. The experiment covered any aspect of the problem in a coherent and structured manner, that allowed to produce a low-uncertainty data for the validation of numerical model. The data covers the unsteady aerodynamics of the floating wind turbine in terms of blade forces, rotor forces and wake. 2D sectional model tests were carried to study the aerodynamics of a low-Reynolds blade profile subjected to a harmonic variation of the angle of attack. The lift coefficient shows an hysteresis cycle that extends in the linear region and grows in strength for higher motion frequencies. The knowledge gained in 2D sectional model tests was exploited to design the rotor of a 1/75 scale model of the DTU 10MW that was used to perform imposed surge motion tests in a wind tunnel. The tower-top forces were measured for several combinations of mean wind speed, surge amplitude and frequency to assess the effect of unsteady aerodynamics on the response of the system. The thrust force, that plays a crucial role in the along-wind dynamics of a floating wind turbine mostly follows the quasi-steady theory. The near-wake of the wind turbine was studied by means of hot-wire measurements, and PIV was utilized to visualize the tip vortex. It is seen that the wake energy is increased in correspondence of the motion frequency and this is likely to be associated with the blade-tip vortex, which travel speed is modified in presence of surge motion.

An Experimental Apparatus for Investigating the Unsteady Aerodynamics of a Floating Wind Turbine

2019 ◽  
Author(s):  
Binrong Wen ◽  
Qi Zhang ◽  
Haoxue Liu ◽  
Xinliang Tian ◽  
Xingjian Dong ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Measurement System ◽  
Detection System ◽  
Unsteady Aerodynamics ◽  
Operating Conditions ◽  
Test Bed ◽  
Ocean Engineering ◽  
Floating Wind Turbine ◽  
Experimental Apparatus ◽  
Fbg Sensors

Abstract In our prior investigations, extensive numerical simulations have been conducted to reveal the unsteady aerodynamics of Floating Wind Turbine (FWT). To validate the simulation results and further deepen the corresponding topics, a dedicated experimental apparatus has been developed by the State Key Laboratory of Mechanical System and Vibration (SKL-MSV) and State Key Laboratory of Ocean Engineering (SKL-OE) at Shanghai Jiao Tong University (SJTU). The main modules of the test bed include a dedicated Wind Generation System (WGS), a Model Wind Turbine (MWT), a 6-DOF (Degree Of Freedom) Motion Control Platform (MCP) and an integrated measurement system. The WGS is able to generate controlled flows with different wind speeds, turbulence intensities, and horizontal/ vertical wind shears. The MWT is equipped with Fiber Bragg Grating (FBG) sensors on the blade surface to monitor the operating conditions. The MCP is developed to generate controlled oscillations to the MWT aiming to model the oscillation of the FWT in offshore environments. The measurement system includes a torque sensor, two 6-DOF load cells, a 3-DOF accelerator, 2 FBG-fibers each with 3 FBG sensors, and a Wake Detection System (WDS) consisting of 6 hot-wire probes. Extensive calibrations are conducted for the WGS and the transducers. Some primary results about the unsteady aerodynamics of the FWT are presented. In the future, the MCP will be replaced by a floating platform to conduct the tests in the wave tank at SKL-OE to reveal the fully coupled dynamics of FWTs.

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