scholarly journals Evaluation of Offshore Wind Turbine Tower Dynamics with Numerical Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Begum Yurdanur Dagli ◽  
Yeşim Tuskan ◽  
Ümit Gökkuş
Keyword(s):  
Numerical Analysis ◽  
Energy Method ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Linear Wave ◽  
Variable Cross ◽  
Ground Acceleration ◽  
Earthquake Force ◽  
Hydrodynamic Wave

A dynamic behaviour of a cylindirical wind tower with variable cross section is investigated under environmental and earthquake forces. The ground acceleration term is represented by a simple cosine function to investigate both normal and parallel components of the earthquake motions located near ground surface. The function of earthquake force is simplified to apply Rayleigh’s energy method. Wind forces acting on above the water level and wave forces acting on below this level are utilized in computations considering earthquake effect for entire structure. The wind force is divided into two groups: the force acting on the tower and the forces acting on the rotor nacelle assembly (RNA). The drag and the inertial wave forces are calculated with water particle velocities and accelerations due to linear wave theory. The resulting hydrodynamic wave force on the tower in an unsteady viscous flow is determined using the Morison equation. The displacement function of the physical system in which dynamic analysis is performed by Rayleigh’s energy method is obtained by the single degree of freedom (SDOF) model. The equation of motion is solved by the fourth-order Runge–Kutta method. The two-way FSI (fluid-structure interaction) technique was used to determine the accuracy of the numerical analysis. The results of computational fluid dynamics and structural mechanics are coupled in FSI analysis by using ANSYS software. Time-varying lateral displacements and the first natural frequency values which are obtained from Rayleigh’s energy method and FSI technique are compared. The results are presented by graphs. It is observed from these graphs that the Rayleigh model can be an alternative way at the prelimanary stage of the structural analysis with acceptable accuracy.

Wave Forces on the Composite Bucket Foundation of Offshore Wind Turbines

2013 ◽  
Vol 405-408 ◽  
pp. 1420-1426 ◽  
Author(s):  
Guang Wei Liu ◽  
Qing He Zhang ◽  
Jin Feng Zhang
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Diffraction Theory ◽  
Wave Force ◽  
Variable Cross Section ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Variable Cross ◽  
Bucket Foundation

A three dimensional numerical model to calculate the wave forces on the composite bucket foundation of the offshore wind turbine is established and the analytical method to approximatively calculate wave forces on the structure with the variable cross section is proposed. Based on the validation of numerical results, wave forces on the composite bucket foundation are calculated under different wave conditions. The variable cross-section of the composite bucket foundation is divided into sections with the approximate same diameter. Comparison with the numerical calculations and analytical results, the wave force on each section can be calculated using Morison equation when the relative diameter is less than 0.2 and using diffraction theory when the relative diameter is more than 0.2.

Experimental Study on the Wave Loads on Monopile and Jacket Type Support of Offshore Wind Turbines

2018 ◽  
Author(s):  
Jing Zhang ◽  
Qin Liu ◽  
Xing Hua Shi ◽  
C. Guedes Soares
Keyword(s):  
Experimental Study ◽  
Wind Turbine ◽  
Nonlinear Wave ◽  
Wave Force ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Wave Loads ◽  
Morison Equation ◽  
Offshore Wind Turbines

As the offshore fixed wind turbine developed, more ones will be installed in the sea field with the depth 15–50 meters. Wave force will be one of the main forces that dominate the design of the wind turbine base, which is calculated using the Morison equation traditionally. This method can predict the wave forces for the small cylinders if the drag and inertia coefficients are obtained accurately. This paper will give a series scaled tests of monopile and jacket type base of the offshore wind turbine in tank to study the nonlinear wave loads.

Dynamic Modeling of Deepwater Offshore Wind Turbine Structures in Gulf of Mexico Storm Conditions

2006 ◽  
Author(s):  
Thomas Zambrano ◽  
Tyler MacCready ◽  
Taras Kiceniuk ◽  
Dominique G. Roddier ◽  
Christian A. Cermelli
Keyword(s):  
Gulf Of Mexico ◽  
Wind Turbine ◽  
Wind Waves ◽  
Line Tension ◽  
Offshore Wind ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Offshore Structure ◽  
Force Coefficient

A Fourier spectrum based model of Gulf of Mexico storm conditions is applied to a 6 degree of freedom analytic simulation of a moored, floating offshore structure fitted with three rotary wind turbines. The resulting heave, surge, and sway motions are calculated using a Newtonian Runge-Kutta method. The angular motions of pitch, roll, and yaw are also calculated in this time-domain progression. The forces due to wind, waves, and mooring line tension are predicted as a function of time over a 4000 second interval. The WAMIT program is used to develop the wave forces on the platform. A constant force coefficient is used to estimate wind turbine loads. A TIMEFLOAT computer code calculates the motion of the system based on the various forces on the structure and the system’s inertia.

scholarly journals Numerical Analysis of a Gravity Substructure for 5MW Offshore Wind Turbine

2018 ◽  
Vol 10 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Min-Su Park ◽  
◽  
Youn-Ju Jeong ◽  
Young-Jun You ◽  
Jeongsoo Kim
Keyword(s):  
Numerical Analysis ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine

Numerical and Experimental Investigation of the Wave Loading on a Three-Legged Offshore Wind Turbine Jacket Platform

2018 ◽  
Author(s):  
Ioannis K. Chatjigeorgiou ◽  
Konstantinos Chatziioannou ◽  
Vanessa Katsardi ◽  
Apostolos Koukouselis ◽  
Euripidis Mistakidis
Keyword(s):  
Wave Structure ◽  
Element Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Forces ◽  
Intermediate Water ◽  
Wave Loads ◽  
Wave Loading ◽  
Scaled Model ◽  
The Time Domain

The purpose of this work is to examine a three-legged jacket tower support system subjected to wave loading. To this end, linear as well as nonlinear wave scenarios are investigated. The structure was designed for offshore wind turbines installed in intermediate water depths. The phenomenon of the wave-structure interaction is examined experimentally with a 1:18 scaled model as well as numerically with the use of Finite Element Model (FEM). The structural calculations were performed using the structural analysis software SAP2000, which was enhanced by a special programming interface that was developed to calculate the wave loading and to directly apply the wave loads on the structural members. The FEM model in combination with the key parameters that are taken into account, provides a good correlation with the experimental results. The wave theories of Airy and Stokes 5th are employed for the calculation of the wave particle kinematics. The resulting wave forces are examined both in the frequency and in the time domain.

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