Numerical simulations of a large offshore wind turbine exposed to turbulent inflow conditions

2018 ◽  
Vol 42 (2) ◽  
pp. 88-96 ◽  
Author(s):  
Galih Bangga ◽  
Giorgia Guma ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Turbulent Inflow ◽  
Background Turbulence ◽  
High Turbulence ◽  
Dynamics Simulations ◽  
The Impact ◽  
Inflow Conditions

This work is intended to investigate the aerodynamic responses of a large generic 10-MW offshore wind turbine under turbulent inflow conditions. The nonlinear lifting line free vortex wake simulations approach is employed for this purpose, computed using the QBlade code. In these studies, the effects of a three-dimensional correction model for the airfoil polars were studied in advance. For this purpose, the blade element momentum computations employing the corrected polars are performed and compared to computational fluid dynamics simulations, and a good agreement is obtained between both employed approaches. Background turbulence is then imposed in the QLLT simulations with the turbulence intensities ranging from low to high turbulence levels (3%–15%). Furthermore, the impact of wind shear from different locations (offshore and onshore) is investigated in this work.

Fully Coupled Three-Dimensional Dynamic Response of a TLP Floating Wind Turbine in Waves and Wind

2012 ◽  
Author(s):  
G. K. V. Ramachandran ◽  
H. Bredmose ◽  
J. N. Sørensen ◽  
J. J. Jensen
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Three Dimensional ◽  
Geographic Location ◽  
Climatic Conditions ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Total System ◽  
Wave Loads ◽  
Aerodynamic Loads

A dynamic model for a tension-leg platform (TLP) floating offshore wind turbine is proposed. The model includes three-dimensional wind and wave loads and the associated structural response. The total system is formulated using 17 degrees of freedom (DOF), 6 for the platform motions and 11 for the wind turbine. Three-dimensional hydrodynamic loads have been formulated using a frequency- and direction-dependent spectrum. While wave loads are computed from the wave kinematics using Morison’s equation, aerodynamic loads are modelled by means of unsteady Blade-Element-Momentum (BEM) theory, including Glauert correction for high values of axial induction factor, dynamic stall, dynamic wake and dynamic yaw. The aerodynamic model takes into account the wind shear and turbulence effects. For a representative geographic location, platform responses are obtained for a set of wind and wave climatic conditions. The platform responses show an influence from the aerodynamic loads, most clearly through a quasi-steady mean surge and pitch response associated with the mean wind. Further, the aerodynamic loads show an influence from the platform motion through more fluctuating rotor loads, which is a consequence of the wave-induced rotor dynamics. In the absence of a controller scheme for the wind turbine, the rotor torque fluctuates considerably, which induces a growing roll response especially when the wind turbine is operated nearly at the rated wind speed. This can be eliminated either by appropriately adjusting the controller so as to regulate the torque or by optimizing the floater or tendon dimensions, thereby limiting the roll motion. Loads and coupled responses are predicted for a set of load cases with different wave headings. Based on the results, critical load cases are identified and discussed. As a next step (which is not presented here), the dynamic model for the substructure is therefore being coupled to an advanced aero-elastic code Flex5, Øye (1996), which has a higher number of DOFs and a controller module.

A Numerical Prediction on the Transient Response of a Spar-Type Floating Offshore Wind Turbine in Freak Waves

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Yan Li ◽  
Xiaoqi Qu ◽  
Liqin Liu ◽  
Peng Xie ◽  
Tianchang Yin ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Numerical Code ◽  
Modulation Method ◽  
Offshore Wind Turbine ◽  
Freak Waves ◽  
Freak Wave ◽  
Floating Offshore Wind Turbine ◽  
The Impact

Abstract Simulations are conducted in time domain to investigate the dynamic response of a spar-type floating offshore wind turbine (FOWT) under the freak wave scenarios. Toward this end, a coupled aero-hydro-mooring in-house numerical code is adopted to perform the simulations. The methodology includes a blade-element-momentum (BEM) model for simulating the aerodynamic loads, a nonlinear model for simulating the hydrodynamic loads, a nonlinear restoring model of Spar buoy, and a nonlinear algorithm for simulating the mooring cables. The OC3 Hywind spar-type FOWT is adopted as an example to study the dynamic response under the freak wave conditions, meanwhile the time series of freak waves are generated using the random frequency components selection phase modulation method. The motion of platform, the tension applied on the mooring lines, and the power generation performance are documented in several cases. According to the simulations, it is indicated that when a freak wave acts on the FOWT, the transient motion of the FOWT is induced in all degrees-of-freedom, as well as the produced power decreases rapidly. Furthermore, the impact of freak wave parameters on the motion of FOWT is discussed.

scholarly journals Effect of Wind Turbulence on Extreme Load Analysis of an Offshore Wind Turbine

2019 ◽  
Author(s):  
Xiaolu Chen ◽  
Zhiyu Jiang ◽  
Qinyuan Li ◽  
Ye Li
Keyword(s):  
Wind Turbine ◽  
Turbulence Intensity ◽  
Environmental Conditions ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Contour Method ◽  
Offshore Wind Turbine ◽  
Extreme Response ◽  
Wind Turbulence ◽  
The Impact

Abstract Evaluation of dynamic responses under extreme environmental conditions is important for the structural design of offshore wind turbines. Previously, a modified environmental contour method has been proposed to estimate extreme responses. In the method, the joint distribution of environmental variables near the cut-out wind speed is used to derive the critical environmental conditions for a specified return period, and the turbulence intensity (TI) of wind is assumed to be a deterministic value. To address more realistic wind conditions, this paper considers the turbulence intensity as a stochastic variable and investigates the impact on the modified environmental contour. Aerodynamic simulations are run over a range of mean wind speeds at the hub height from 9–25 m/s and turbulence levels between 9%–15%. Dynamic responses of a monopile offshore wind turbine under extreme conditions were studied, and the importance of considering the uncertainties associated with wind turbulence is highlighted. A case of evaluating the extreme response for 50-year environmental contour is given as an example of including TI as an extra variant in environmental contour method. The result is compared with traditional method in which TI is set as a constant of 15%. It shows that taking TI into consideration based on probabilistic method produces a lower extreme response prediction.

scholarly journals EXPERIMENTAL STUDY ON THE LOADING AND SCOUR OF THE JACKET TYPE OFFSHORE WIND TURBINE FOUNDATION

2011 ◽  
Vol 1 (32) ◽  
pp. 25
Author(s):  
Ray-Yeng Yang ◽  
Hsin-Hung Chen ◽  
Hwung-Hweng Hwung ◽  
Wen-Pin Jiang ◽  
Nian-Tzu Wu
Keyword(s):  
Wind Turbine ◽  
Water Depth ◽  
Fixed Bed ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Wave Flume ◽  
Wave Basin ◽  
Scour Protection ◽  
The Impact

A 1:36 scale model tests were carried out in the Medium Wave Flume (MWF) and Near-shore Wave Basin (NSWB) at the Tainan Hydraulics Laboratory (THL) with the jacket type offshore wind turbine foundation located in the test area. The loading of typhoon wave with current on the jacket type offshore wind turbine foundation was investigated in the MWF with fixed bed experiment. Meanwhile, the scour around the jacket type offshore wind turbine foundation exposed to wave and current was conducted in the NSWB with the moveable bed experiment. Two locations (water depth 12m and 16m) of the foundations are separately simulated in this study. Based on the analysis from the former NSWB experimental results, the suitable scour protection of a four-layer work around the foundation is also proposed to the impact of scour. Finally, a four-layer scour protection is tested and found to be effective in preventing scour around jacket type foundation of offshore wind turbines at water depth 12m and 16m.

Assessing the Impact of Integrating Energy Storage on the Dynamic Response of a Spar-Type Floating Wind Turbine

2019 ◽  
Author(s):  
Charise Cutajar ◽  
Tonio Sant ◽  
Robert N. Farrugia ◽  
Daniel Buhagiar
Keyword(s):  
Energy Storage ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Energy Demand ◽  
Large Scale ◽  
Preliminary Investigation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Wind Turbine ◽  
The Impact

Abstract Offshore wind technology is at the forefront of exploiting renewable energy at sea. The latest innovations in the field comprise floating wind turbines deployed in deep waters that are capable of intercepting the stronger, less turbulent winds farther away from the landmass. Despite being able to augment the power harnessed, wind resources remain intermittent in nature, and so unable to satisfy the energy demand at all times. Energy storage systems (ESS) are therefore being considered a key component to smoothen out the supply-demand mismatch when wind penetration into electricity grids increases. Yet, multiple issues pertaining to the integration of ESSs on large-scale projects arise, including economic, environmental and safety considerations. This paper presents a novel concept for integrating a hydro-pneumatic energy storage (HPES) system within a spar-type floating offshore wind turbine (FOWT) platform. It aims to assess the technical feasibility of integrating the storage unit within the floater. A preliminary investigation on the influence of integrated storage on the static stability and hydrostatic response of a conventional ballast-stabilised FOWT is conducted, followed by numerical simulations for the dynamic response using ANSYS® AQWA™. Based on the results presented, several conclusions are drawn on the implications of integrating energy storage with floating wind turbine structures. Finally, a preliminary assessment of the thermal efficiency of the storage system based on this specific embodiment is also presented and discussed.

scholarly journals Modelling Rain Drop Impact of Offshore Wind Turbine Blades

2012 ◽  
Author(s):  
M. H. Keegan ◽  
D. H. Nash ◽  
M. M. Stack
Keyword(s):  
Wind Turbine ◽  
Impact Damage ◽  
Turbine Blades ◽  
Leading Edge ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Turbine Blades ◽  
Erosion Testing ◽  
Software Modelling ◽  
The Impact

The effects of rain and hail erosion and impact damage on the leading edge of offshore wind turbine blades have been investigated. A literature review was conducted to establish the effects of exposure to these conditions and also to investigate the liquid impact phenomena and their implications for leading edge materials. The role of Explicit Dynamics software modelling in simulating impact events was then also established. Initial rain impact modelling is then discussed with the results showing good agreement with theoretical predictions both numerically and with respect to the temporal and spatial development of the impact event. Future development of the rain model and a proposed hail model are then detailed. Planned rain impact and erosion testing work is addressed which will be used to validate, inform and compliment the ongoing modelling efforts.

Modelling the Dynamic Response and Loads of Floating Offshore Wind Turbine Structures With Integrated Compressed Air Energy Storage

2017 ◽  
Author(s):  
Tonio Sant ◽  
Daniel Buhagiar ◽  
Robert N. Farrugia
Keyword(s):  
Energy Storage ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Compressed Air ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Compressed Air Energy Storage ◽  
Floating Offshore Wind Turbine ◽  
The Impact

Nowadays there is increased interest to incorporate energy storage technologies with wind turbines to mitigate grid-related challenges resulting from the intermittent supply from large-scale offshore wind farms. This paper presents a new concept to integrate compressed air energy storage (CAES) in floating offshore wind turbine (FOWT) structures. The FOWT support structures will serve a dual purpose: to provide the necessary buoyancy to maintain the entire wind turbine afloat and stable under different met-ocean conditions and to act as a pressure vessel for compressed air energy storage on site. The proposed concept involves a hydro-pneumatic accumulator installed on the seabed to store pressurized deep sea water that is pneumatically connected to the floating support structure by means of an umbilical conduit. The present study investigates the technical feasibility of this concept when integrated in tension leg platforms (TLPs). The focus is on the impact of the additional floating platform weight resulting from the CAES on the dynamic response characteristics and loads when exposed to irregular waves. A simplified model for sizing the TLP hull for different energy storage capacities is initially presented. This is then used to evaluate the dynamic response of nine different TLP geometries when supporting the NREL1 5MW baseline wind turbine model. Numerical simulations are carried out using the marine engineering software tool ANSYS Aqwa©. The work provides an insight on how TLP structures supporting wind turbines may be optimised to facilitate the integration of the proposed CAES concept. It is shown that it is technically feasible to integrate CAES capacities on the order of Megawatt-Hours within TLP structures without compromising the stability of the floating system; although this would involve a substantial increase in the total structure weight.

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