Experimental Measurements of WindFloat 1 Prototype Responses and Comparison With Numerical Model

2018 ◽  
Author(s):  
Christian Cermelli ◽  
Charlotte Leroux ◽  
Sandra Díaz Domínguez ◽  
Antoine Peiffer
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Wind Turbines ◽  
Degrees Of Freedom ◽  
Scaled Model ◽  
Analysis Methodology ◽  
Fit For Purpose ◽  
Numerical Tools ◽  
The Time Domain ◽  
6 Degrees Of Freedom

This paper presents experimental results of WindFloat 1 platform and comparisons with the numerical model developed by Principle Power. The WindFloat platform is designed to support multi-megawatt wind turbines. A full-scale prototype was installed offshore Portugal from 2011 to 2016, and produced 17GWh into the Portuguese grid. An extensive monitoring system was installed, including a wave rider buoy, 6-degrees of freedom measurement devices, anemometers, strain gauges, turbine monitoring instruments. Important results obtained during the measurement campaign are described in this paper. These include power predictions, turbine and tower loads, and platform motions. Comparison with numerical simulations are also provided. The numerical analysis methodology includes fully coupled simulations, based on Orcaflex, a commercially available state-of-the-art software to compute the hydrodynamic response of floating systems, combined in the time-domain with FAST, a well-established numerical tool for the design of wind turbines. Results of these comparisons show that the numerical tools are fit for purpose, and were used to calibrate some hydrodynamic coefficients that cannot be obtained accurately with numerical analysis or scaled model tests.

scholarly journals Numerical Analysis of a Single-Stage Fast Linear Transformer Driver Using Field-Circuit Coupled Time-Domain Finite Integration Theory

2020 ◽  
Vol 10 (22) ◽  
pp. 8301
Author(s):  
Hao Qiu ◽  
Shuhong Wang ◽  
Naming Zhang ◽  
Fengju Sun ◽  
Zhiguo Wang ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Time Domain ◽  
Degrees Of Freedom ◽  
Single Stage ◽  
Impedance Boundary Condition ◽  
Integration Theory ◽  
Nonuniform Grids ◽  
Impedance Boundary ◽  
Linear Transformer Driver ◽  
The Time Domain

The focus of this paper is numerical analysis on the performance of a newly designed mega-ampere (MA) class single-stage fast linear transformer driver (FLTD) with 24 separate columns in the China Z-pinch driver CZ34. However, the internal structure and media distribution of the FLTD induction cavity is very complicated and the short rise time of the bricks’ discharge current will make spatial discretization much denser, resulting in a dramatic increase in the computational complexity of a 3-D model. In this paper, the electromagnetic (EM) characteristics of the single-stage FLTD with 24-separate columns are investigated based on the time-domain finite integration theory (TD-FIT). The discharge currents of brick capacitors in the circuit model are coupled to the field model as excitations. The grid size of the key components in FLTD cavity are refined by nonuniform grids. To further reduce the number of degrees of freedom (DoFs), the surface impedance boundary condition (SIBC) is used to model good conductors. Measurements and simulation results demonstrate that TD-FIT is effective and accurate in analyzing the EM transients of FLTD. Equivalent inductance of the discharging brick will increase by ~35 nH due to the mutual flux linkage among neighboring bricks when all the 23-bricks are triggered synchronously.

scholarly journals Numerical and Physical Modeling of a Tension-Leg Platform for Offshore Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3554
Author(s):  
Daniel Walia ◽  
Paul Schünemann ◽  
Hauke Hartmann ◽  
Frank Adam ◽  
Jochen Großmann
Keyword(s):  
Numerical Model ◽  
Wind Turbines ◽  
Model Testing ◽  
Offshore Wind ◽  
Scaled Model ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Cost Efficient ◽  
Decay Tests ◽  
Floating Platforms

In order to tap the world wide offshore wind resources above deep waters, cost efficient floating platforms are inevitable. Tension-Leg Platforms (TLPs) could enable that crucial cost reduction in floating wind due to their smaller size and lighter weight compared to spars and semi-submersibles. The continuous development of the GICON®-TLP is driven by computer-aided engineering. So-called aero-hydro-servo-elastic coupled simulations are state-of-the-art for predicting loads and simulating the global system behavior for floating offshore wind turbines. Considering the complexity of such simulations, it is good scientific praxis to validate these numerical calculations by use of scaled model testing. This paper addresses the setup of the scaled model testing as carried out at the offshore basin of the École Centrale de Nantes, as well as the numerical model for the GICON®-TLP. The results of dedicated decay tests of the scaled model are used to validate the computational model at the first stage and to determine the natural frequencies of the system. Besides different challenges to the scaled model during the survey, it was possible to take these difficulties into account when updating the numerical model. The results show good agreements for the tank tests and the numerical model.

Experimental RAO’s Analysis of a Monolithic Concrete SPAR Structure for Offshore Floating Wind Turbines

2015 ◽  
Author(s):  
Alexis Campos ◽  
Climent Molins ◽  
Xavier Gironella ◽  
Pau Trubat ◽  
Daniel Alarcón
Keyword(s):  
Numerical Model ◽  
Wind Turbines ◽  
Vision System ◽  
Stereoscopic Vision ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Stokes Wave ◽  
Floating Platform ◽  
Scaled Model ◽  
Wave Flume

Nowadays the offshore wind energy market is clearly oriented to be extended around the world. Bottom fixed solutions for supporting offshore wind turbines are useful in shallow waters which are available in a limited extent unless a continental shelf exists. Considering the Oil & Gas background knowledge, move from bottom fixed solutions to floating solutions is not a technical challenge, but the cost of each structure in terms of industry profit is currently the main issue for its commercial implementation. That point has induced huge research efforts on the topic. Recently, a new concept consisting of a monolithic concrete SPAR platform was experimentally and numerically studied in the framework of the AFOSP KIC-InnoEnergy project (Alternative Floating Platform Designs for Offshore Wind Towers using Low Cost Materials) [1] [2]. The studies comprised a set of hydrodynamic tests performed in the CIEM wave flume facility at UPC, with a 1:100 scaled model assuming Froude similitude. The whole test campaign includes free decay tests, RAO’s determination, regular and irregular waves with and without wind mean force. For the determination of the platform RAO’s, a set of 21 regular waves trains with periods ranging from 0.8s up to 4.8s were applied. The 6 DOF motions of the platform were measured with an infrared stereoscopic vision system. In this paper, a summary of pitch and heave RAO’s tests will be presented with the main objective to calibrate and validate the accuracy of the Morison-based numerical model for floating wind turbine platforms developed at the Universitat Politècnica de Catalunya. Because the wave flume spatial constraints, both Airy and Stokes wave theories are necessary to reproduce the correct wave kinematics. The numerical model includes both theories and a comparison between them has been done, checking the validity range of each one. The simulations revealed a reasonable good agreement with the experimental results, as well with the computed RAO’s in commercial software.

scholarly journals Numerical analysis of VAWT wind turbines: Joukowski vs classical NACA rotor’s blades

2019 ◽  
Vol 158 ◽  
pp. 1194-1201
Author(s):  
Jabir Ubaid Parakkal ◽  
Khadije El Kadi ◽  
Ameen El-Sinawi ◽  
Sherine Elagroudy ◽  
Isam Janajreh
Keyword(s):  
Numerical Analysis ◽  
Wind Turbines

scholarly journals Numerical Parametric Study on the Effectiveness of the Contact-Point Response of a Stationary Vehicle for Bridge Health Monitoring

2021 ◽  
Vol 11 (15) ◽  
pp. 7028
Author(s):  
Ibrahim Hashlamon ◽  
Ehsan Nikbakht ◽  
Ameen Topa ◽  
Ahmed Elhattab
Keyword(s):  
Numerical Model ◽  
Health Monitoring ◽  
Contact Point ◽  
Response Spectra ◽  
Roughness Effects ◽  
Moving Vehicle ◽  
Bridge Health Monitoring ◽  
Vehicle Response ◽  
Instrumented Vehicle ◽  
The Time Domain

Indirect bridge health monitoring is conducted by running an instrumented vehicle over a bridge, where the vehicle serves as a source of excitation and as a signal receiver; however, it is also important to investigate the response of the instrumented vehicle while it is in a stationary position while the bridge is excited by other source of excitation. In this paper, a numerical model of a stationary vehicle parked on a bridge excited by another moving vehicle is developed. Both stationary and moving vehicles are modeled as spring–mass single-degree-of-freedom systems. The bridges are simply supported and are modeled as 1D beam elements. It is known that the stationary vehicle response is different from the true bridge response at the same location. This paper investigates the effectiveness of contact-point response in reflecting the true response of the bridge. The stationary vehicle response is obtained from the numerical model, and its contact-point response is calculated by MATLAB. The contact-point response of the stationary vehicle is investigated under various conditions. These conditions include different vehicle frequencies, damped and undamped conditions, different locations of the stationary vehicle, road roughness effects, different moving vehicle speeds and masses, and a longer span for the bridge. In the time domain, the discrepancy of the stationary vehicle response with the true bridge response is clear, while the contact-point response agrees well with the true bridge response. The contact-point response could detect the first, second, and third modes of frequency clearly, unlike the stationary vehicle response spectra.

scholarly journals Numerical Analysis of Viscoelastic Rotating Beam with Variable Fractional Order Model Using Shifted Bernstein–Legendre Polynomial Collocation Algorithm

2021 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Cundi Han ◽  
Yiming Chen ◽  
Da-Yan Liu ◽  
Driss Boutat
Keyword(s):  
Numerical Analysis ◽  
Fractional Order ◽  
Governing Equation ◽  
Numerical Solutions ◽  
Bernstein Polynomials ◽  
Matrix Product ◽  
Algebraic Equations ◽  
Rotating Beam ◽  
The Matrix ◽  
The Time Domain

This paper applies a numerical method of polynomial function approximation to the numerical analysis of variable fractional order viscoelastic rotating beam. First, the governing equation of the viscoelastic rotating beam is established based on the variable fractional model of the viscoelastic material. Second, shifted Bernstein polynomials and Legendre polynomials are used as basis functions to approximate the governing equation and the original equation is converted to matrix product form. Based on the configuration method, the matrix equation is further transformed into algebraic equations and numerical solutions of the governing equation are obtained directly in the time domain. Finally, the efficiency of the proposed algorithm is proved by analyzing the numerical solutions of the displacement of rotating beam under different loads.

scholarly journals Performance Analysis on the Use of Oscillating Water Column in Barge-Based Floating Offshore Wind Turbines

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 475
Author(s):  
Payam Aboutalebi ◽  
Fares M’zoughi ◽  
Izaskun Garrido ◽  
Aitor J. Garrido
Keyword(s):  
Wind Turbines ◽  
Positive Impact ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Water Columns ◽  
Numerical Tools ◽  
Oscillating Water Columns ◽  
The Given ◽  
The Waves

Undesired motions in Floating Offshore Wind Turbines (FOWT) lead to reduction of system efficiency, the system’s lifespan, wind and wave energy mitigation and increment of stress on the system and maintenance costs. In this article, a new barge platform structure for a FOWT has been proposed with the objective of reducing these undesired platform motions. The newly proposed barge structure aims to reduce the tower displacements and platform’s oscillations, particularly in rotational movements. This is achieved by installing Oscillating Water Columns (OWC) within the barge to oppose the oscillatory motion of the waves. Response Amplitude Operator (RAO) is used to predict the motions of the system exposed to different wave frequencies. From the RAOs analysis, the system’s performance has been evaluated for representative regular wave periods. Simulations using numerical tools show the positive impact of the added OWCs on the system’s stability. The results prove that the proposed platform presents better performance by decreasing the oscillations for the given range of wave frequencies, compared to the traditional barge platform.

4D in in vivo 2-photon laser scanning fluorescence microscopy with sample motion in 6 degrees of freedom

2011 ◽  
Vol 200 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Sabine Scheibe ◽  
Mario M. Dorostkar ◽  
Christian Seebacher ◽  
Rainer Uhl ◽  
Frank Lison ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Laser Scanning ◽  
Degrees Of Freedom ◽  
Sample Motion ◽  
6 Degrees Of Freedom

Workspace, dexterity and dimensional optimization of microhexapod

2015 ◽  
Vol 35 (4) ◽  
pp. 341-347 ◽  
Author(s):  
E. Rouhani ◽  
M. J. Nategh
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Screw Theory ◽  
Design Parameters ◽  
Dimensional Synthesis ◽  
Content Type ◽  
Workspace Analysis ◽  
The Difference ◽  
Flexure Joints ◽  
6 Degrees Of Freedom

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

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