Numerical Simulation of Wave Run-Ups due to Nonlinear Interaction Between Stokes Waves and Offshore Wind Turbines

2016 ◽  
Author(s):  
Yu-Hsien Lin ◽  
Jing-Fu Chen ◽  
Po-Ying Lu
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Research Centre ◽  
Wave Steepness ◽  
Large Wave ◽  
Wave Flume ◽  
Stokes Waves ◽  
The Difference ◽  
Run Up

This paper conducts a RANS solver with k-ε turbulent closure to simulate hydrodynamics of wave run-ups of three types of wind turbine foundations, including monopile, gravity-based and tripod support structures. In this study, a semi-empirical formula is developed and calibrated based on velocity stagnation head theory by means of a CFD model, FLUENT. The numerical results are validated by the experimental data, which were implemented in the Large Wave Flume (GWK) of the Coastal Research Centre (FZK) in Hannover and published by Mo et al. (2007) [1]. It is indicated that the difference of normalized run-up envelopes among these wind turbine foundations is smaller for higher wave steepness than those for lower wave steepness. It is also obvious that the tendency of maximum run-up heights is considerably correlated with higher nonlinearity, whereas an opposite trend is obtained for minimum run-up envelops. Eventually, a calibrated run-up parameter is obtained by the present numerical simulation and found that the value becomes smaller with respect to higher nonlinearity and run-up heights.

scholarly journals Dynamic Loads and Response of a Spar Buoy Wind Turbine with Pitch-Controlled Rotating Blades: An Experimental Study

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3598
Author(s):  
Sara Russo ◽  
Pasquale Contestabile ◽  
Andrea Bardazzi ◽  
Elisa Leone ◽  
Gregorio Iglesias ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Laboratory Data ◽  
Nonlinear Behavior ◽  
Offshore Wind ◽  
Small Scale ◽  
Wave Steepness ◽  
Design Factor

New large-scale laboratory data are presented on a physical model of a spar buoy wind turbine with angular motion of control surfaces implemented (pitch control). The peculiarity of this type of rotating blade represents an essential aspect when studying floating offshore wind structures. Experiments were designed specifically to compare different operational environmental conditions in terms of wave steepness and wind speed. Results discussed here were derived from an analysis of only a part of the whole dataset. Consistent with recent small-scale experiments, data clearly show that the waves contributed to most of the model motions and mooring loads. A significant nonlinear behavior for sway, roll and yaw has been detected, whereas an increase in the wave period makes the wind speed less influential for surge, heave and pitch. In general, as the steepness increases, the oscillations decrease. However, higher wind speed does not mean greater platform motions. Data also indicate a significant role of the blade rotation in the turbine thrust, nacelle dynamic forces and power in six degrees of freedom. Certain pairs of wind speed-wave steepness are particularly unfavorable, since the first harmonic of the rotor (coupled to the first wave harmonic) causes the thrust force to be larger than that in more energetic sea states. The experiments suggest that the inclusion of pitch-controlled, variable-speed blades in physical (and numerical) tests on such types of structures is crucial, highlighting the importance of pitch motion as an important design factor.

scholarly journals Numerically and Experimentally Verified Design of a Small Wind Turbine with Injection Molded Blade

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 776
Author(s):  
Byunghui Kim ◽  
Sang-June Park ◽  
Seokyoung Ahn ◽  
Myung-Gon Kim ◽  
Hyung-Gun Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Power Systems ◽  
Wind Turbine ◽  
Wind Power ◽  
Offshore Wind ◽  
Power Coefficient ◽  
Manufacturing Method ◽  
Small Wind Turbine ◽  
Verification Methods ◽  
Wind Power Systems

Although mega-watt class onshore and offshore wind power systems are used to generate power due to their cost-effectiveness, small wind power systems are important for household usages. Researchers have focused on aerodynamic characteristics as a conceptual design from their previous studies on Archimedes spiral wind turbines. Here, we verified the design of a small wind turbine AWM-750D (100 W capacity) via both numerical simulation and experimentation. We used commercial code ANSYS CFX for numerical simulation and compared turbulence models and surface roughness for determining the performance. To obtain reliable and robust blades, we analyzed the effective manufacturing method with Moldflow. Through a test with an open-suction type atmospheric boundary layer wind tunnel, we varied wind speed from 4.0 m/s to the rated value of 12.5 m/s and obtained 106 W, equivalent to a power coefficient of 0.205. In addition, we compared the numerical and experimental power vs. rotational speed and found the former is 6.5% lower than the latter. In this study, we proved that numerical simulations can act as design verification methods to predict wind turbine performances and reliable manufacturing. Through our research, we provided the prototype of a small wind turbine with 100 W to act as an efficient electric power supplier for households and also the stable manufacturing process for complex spiral blades using injection molding.

Dynamic Response of a Spar-Type Floating Wind Turbine at Power Generation

2014 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Shigeo Yoshida ◽  
Soichiro Kiyoki ◽  
Iku Sato ◽  
Shigesuke Ishida
Keyword(s):  
Numerical Simulation ◽  
Power Generation ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Prestressed Concrete ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Foundation ◽  
Mooring Dynamics ◽  
Nagasaki Prefecture

In this paper, dynamic response of a Floating Offshore Wind Turbine (FOWT) with spar-type floating foundation at power generation is presented. The FOWT mounts a 100kW wind turbine of down-wind type, with the rotor’s diameter of 22m and a hub-height of 23.3m. The floating foundation consists of PC-steel hybrid spar. The upper part is made of steel whereas the lower part made of prestressed concrete segments. The FOWT was installed at the site about 1km offshore from Kabashima Island, Goto city, Nagasaki prefecture on June 11th, 2012. Since then, the field measurement had been made until its removal in June 2013. In this paper, the dynamic behavior during the power generation is presented, where the comparison with the numerical simulation by aero-hydro-servo-mooring dynamics coupled program is made.

Numerical Simulation of Dynamics of a Spar Type Floating Wind Turbine and Comparison With Laboratory Measurements

2016 ◽  
Author(s):  
Hyunseong Min ◽  
Cheng Peng ◽  
Fei Duan ◽  
Zhiqiang Hu ◽  
Jun Zhang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Numerical Simulations ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Deep Water ◽  
Offshore Wind ◽  
Wind Loads ◽  
Floating Offshore Wind Turbines ◽  
The Cost

Wind turbines are popular for harnessing wind energy. Floating offshore wind turbines (FOWT) installed in relatively deep water may have advantages over their on-land or shallow-water cousins because winds over deep water are usually steadier and stronger. As the size of wind turbines becomes larger and larger for reducing the cost per kilowatt, it could bring installation and operation risks in the deep water due to the lack of track records. Thus, together with laboratory tests, numerical simulations of dynamics of FOWT are desirable to reduce the probability of failure. In this study, COUPLE-FAST was initially employed for the numerical simulations of the OC3-HYWIND, a spar type platform equipped with the 5-MW baseline wind turbine proposed by National Renewable Energy Laboratory (NREL). The model tests were conducted at the Deepwater Offshore Basin in Shanghai Jiao Tong University (SJTU) with a 1:50 Froude scaling [1]. In comparison of the simulation using COUPLE-FAST with the corresponding measurements, it was found that the predicted motions were in general significantly smaller than the related measurements. The main reason is that the wind loads predicted by FAST were well below the related measurements. Large discrepancies are expected because the prototype and laboratory wind loads do not follow Froude number similarity although the wind speed was increased (or decreased) in the tests such that the mean surge wind force matched that predicted by FAST at the nominal wind speed (Froude similarity) in the cases of a land wind turbine [1]. Therefore, an alternative numerical simulation was made by directly inputting the measured wind loads to COUPLE instead of the ones predicted by FAST. The related simulated results are much improved and in satisfactory agreement with the measurements.

Numerical Simulation for the Starting Characteristics of a Wind Turbine

2020 ◽  
Vol 38 ◽  
pp. 215-221
Author(s):  
Anna Kuwana ◽  
Xue Yan Bai ◽  
Dan Yao ◽  
Haruo Kobayashi
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farms ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Optimum Shape ◽  
Blade Thickness ◽  
Basic Characteristics ◽  
Starting Characteristics

There are many types of wind turbine. Large propeller-type wind turbines are used mainly for large wind farms and offshore wind power generation. Small vertical-axis wind turbines (VAWTs) are often used in distributed energy systems. In previous studies on wind turbines, the basic characteristics such as torque coefficient have often been obtained during rotation, with the turbine rotating at a constant speed. Such studies are necessary for the proper design of wind turbines. However, it is also necessary to conduct research under conditions in which the wind direction and wind speed change over time. Numerical simulation of the starting characteristics is carried out in this study. Based on the flow field around the wind turbine, the force required to rotate the turbine is calculated. The force used to stop the turbine is modeled based on friction in relation to the bearing. Equations for the motion of the turbine are solved by their use as external force. Wind turbine operation from the stationary state to the start of rotation is simulated. Five parameters, namely, blade length, wind turbine radius, overlap, gap, and blade thickness, are changed and the optimum shape is obtained. The simulation results tend to qualitatively agree with the experimental results for steadily rotating wind turbines in terms of two aspects: (1) the optimal shape has an 20% overlap of the turbine radius, and (2) the larger the gap, the lower the efficiency.

scholarly journals Model Test and Numerical Simulation of Grouted Connections for Offshore Wind Turbine Under Static Axial Load

2020 ◽  
Vol 8 (7) ◽  
pp. 543
Author(s):  
Weiqiu Zhong ◽  
Wuxu Li ◽  
Tao Yang ◽  
Deming Liu ◽  
Lintao Li
Keyword(s):  
Numerical Simulation ◽  
Bearing Capacity ◽  
Wind Turbine ◽  
Model Test ◽  
Axial Load ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Shear Keys ◽  
Better Than

The bearing capacity of the grouted connections is investigated through the model test and numerical simulation with two rates (low and high) and four kinds of specimens: shorter without shear keys, shorter with shear keys, longer with shear keys, and conical with shear keys. It reveals that the bearing characteristics of the specimen of longer with shear keys is worse than the specimen of conical with shear keys, but better than the specimen of shorter with shear keys. Moreover, the bearing characteristics of the specimen of shorter without shear keys is the worst one.

scholarly journals WAVE RUN-UP OBSERVATIONS ON REVETMENTS WITH DIFFERENT POROSITIES

2012 ◽  
Vol 1 (33) ◽  
pp. 73 ◽  
Author(s):  
Stefan Schimmels ◽  
Michalis Vousdoukas ◽  
Dagmara Wziatek ◽  
Katharina Becker ◽  
Fabian Gier ◽  
...  
Keyword(s):  
Data Analysis ◽  
Concrete Block ◽  
Video Data ◽  
Coastal Protection ◽  
Large Wave ◽  
Wave Flume ◽  
New Type ◽  
Run Up ◽  
Highly Porous ◽  
Good Agreement

Wave run-up plays an important role in the design of coastal protection structures. However, none of the existing formulae for wave run-up predictions explicitly considers the effect of revetment porosity. Recently, two revetments have been tested in the Large Wave Flume (GWK) of Forschungszentrum Küste (FZK), a new type of highly porous polyurethane bonded (PBA revetment) revetment and a smooth interlocked pattern placed concrete block revetment (IPPB revetment), which is considered as “weakly permeable” for the present study. Wave run-up is evaluated by video data analysis based on timestack image processing. The results derived from the timestacks are compared to run-up data measured with conventional wire gauges and the good agreement demonstrates the accuracy and reliability of the video data analysis. The effect of the porosity of the revetment is incorporated into the EuroTop wave run-up formula, showing that for the present case it may reduce the relative run-up heights Ru,2%/Hm0 by about 25 % to 50 % as compared to a smooth impermeable slope.

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