scholarly journals Fully Mechatronical Design of an HIL System for Floating Devices

Robotics ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 39 ◽  
Author(s):  
Hermes Giberti ◽  
Francesco La Mura ◽  
Gabriele Resmini ◽  
Marco Parmeggiani
Keyword(s):  
Wind Tunnel ◽  
Ocean Basin ◽  
Research Field ◽  
Offshore Wind ◽  
Sea Waves ◽  
Floating Bodies ◽  
Scaled Model ◽  
Offshore Wind Turbines ◽  
Computational Fluid Dynamics Cfd ◽  
Model Subject

Recent simulation developments in Computational Fluid Dynamics (CFD) have widely increased the knowledge of fluid–structure interaction. This has been particularly effective in the research field of floating bodies such as offshore wind turbines and sailboats, where air and sea are involved. Nevertheless, the models used in the CFD analysis require several experimental parameters in order to be completely calibrated and capable of accurately predicting the physical behaviour of the simulated system. To make up for the lack of experimental data, usually wind tunnel and ocean basin tests are carried out. This paper presents a fully mechatronical design of an Hardware In the Loop (HIL) system capable of simulating the effects of the sea on a physical scaled model positioned in a wind tunnel. This system allows one to obtain all the required information to characterize a model subject, and at the same time to assess the effects of the interaction between wind and sea waves. The focus of this work is on a complete overview of the procedural steps to be followed in order to reach a predefined performance.

Hybrid Model Tests for Floating Offshore Wind Turbines

2019 ◽  
Author(s):  
Maxime Thys ◽  
Alessandro Fontanella ◽  
Federico Taruffi ◽  
Marco Belloli ◽  
Petter Andreas Berthelsen
Keyword(s):  
Wind Tunnel ◽  
Real Time ◽  
Hybrid Model ◽  
Wind Turbines ◽  
Ocean Basin ◽  
Model Testing ◽  
Model Tests ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Abstract Model testing of offshore structures has been standard practice over the years and is often recommended in guidelines and required in certification rules. The standard objectives for model testing are final concept verification, where it is recommended to model the system as closely as possible, and numerical code calibration. Model testing of floating offshore wind turbines is complex due to the response depending on the aero-hydro-servo-elastic system, but also due to difficulties to perform model tests in a hydrodynamic facility with correctly scaled hydrodynamic, aerodynamic and inertial loads. The main limitations are due to the Froude-Reynolds scaling incompatibility, and the wind generation. An approach to solve these issues is by use of hybrid testing where the system is divided in a numerical and a physical substructure, interacting in real-time with each other. Depending on the objectives of the model tests, parts of a physical model of a FOWT can then be placed in a wind tunnel or an ocean basin, where the rest of the system is simulated. In the EU H2020 LIFES50+ project, hybrid model tests were performed in the wind tunnel at Politecnico di Milano, as well as in the ocean basin at SINTEF Ocean. The model tests in the wind tunnel were performed with a physical wind turbine positioned on top of a 6DOF position-controlled actuator, while the hydrodynamic loads and the motions of the support structure were simulated in real-time. For the tests in the ocean basin, a physical floater with tower subject to waves and current was used, while the simulated rotor loads were applied on the model by use of a force actuation system. The tests in both facilities are compared and recommendations on how to combine testing methodologies in an optimal way are discussed.

scholarly journals 6-DoF Hydrodynamic Modelling for Wind Tunnel Hybrid/HIL Tests of FOWT: The Real-Time Challenge

2018 ◽  
Author(s):  
Ilmas Bayati ◽  
Alan Facchinetti ◽  
Alessandro Fontanella ◽  
Marco Belloli
Keyword(s):  
Wind Tunnel ◽  
Numerical Approach ◽  
Ocean Basin ◽  
Offshore Wind ◽  
Hydrodynamic Modelling ◽  
Hybrid Testing ◽  
Offshore Wind Turbines ◽  
Testing Methodology ◽  
Code Comparison ◽  
Floating Offshore Wind Turbines

This paper deals with the numerical approach and technical implementation of the 6-DoF hydrodynamic modelling, combined with the Politecnico di Milano HexaFloat robot, adopted for wind tunnel Hybrid/HIL tests floating offshore wind turbines. The hybrid testing methodology, along with its ocean-basin counterpart, is currently being considered as a valuable upgrade in the model scale experiments, for its capability to get rid of the typical scaling issues of such systems. The work reports an overview of the setup, the general testing methodology, presenting the main challenges about the deployment on the realtime hardware, summarizing the key solving choices. A set of results related to code-to-code comparison between the optimized HIL numerical model and the reference FAST computations are included, confirming the correctness of the approach.

Verification Study of CFD Simulation of Semi-Submersible Floating Offshore Wind Turbine Under Regular Waves

2021 ◽  
Author(s):  
Yu Wang ◽  
Hamn-Ching Chen ◽  
Guilherme Vaz ◽  
Simon Mewes
Keyword(s):  
Cfd Simulation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Regular Waves ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Spatial Convergence ◽  
Goal Response ◽  
Computational Fluid Dynamics Cfd ◽  
Response Amplitude Operators

Abstract Utilization of Computational Fluid Dynamics (CFD) codes to perform hydrodynamic analysis of Floating Offshore Wind Turbines (FOWTs) is increasing recently. However, verification studies of the simulations that quantifying numerical uncertainties and permitting a detailed validation in a next phase is often disregarded. In this work, a verification study of CFD simulations of a semi-submersible FOWT design under regular waves is performed. To accomplish this goal, Response Amplitude Operators (RAOs) are derived from the computational results of the heave, surge and pitch motions. Four grids with different grid sizes with a constant refinement ratio are generated for verification of spatial convergence. Three different time increments are paired with each grid for verification of temporal convergence. The verification study is performed by estimation of the numerical errors and uncertainties using procedures proposed by Eca and Hoekstra [1].

A hybrid methodology for wind tunnel testing of floating offshore wind turbines

2020 ◽  
Vol 210 ◽  
pp. 107592
Author(s):  
M. Belloli ◽  
I. Bayati ◽  
A. Facchinetti ◽  
A. Fontanella ◽  
H. Giberti ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Wind Tunnel Testing ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Hybrid Methodology ◽  
Tunnel Testing

Model Tests on the Long-Term Dynamic Performance of Offshore Wind Turbines Founded on Monopiles in Sand

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Zhen Guo ◽  
Luqing Yu ◽  
Lizhong Wang ◽  
S. Bhattacharya ◽  
G. Nikitas ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbines ◽  
Model Tests ◽  
Offshore Wind ◽  
Frequency Change ◽  
Test Results ◽  
Scaled Model ◽  
Structural Dynamic ◽  
Offshore Wind Turbines

The dynamic response of the supporting structure is critical for the in-service stability and safety of offshore wind turbines (OWTs). The aim of this paper is to first illustrate the complexity of environmental loads acting on an OWT and reveal the significance of its structural dynamic response for the OWT safety. Second, it is aimed to investigate the long-term performance of the OWT founded on a monopile in dense sand. Therefore, a series of well-scaled model tests have been carried out, in which an innovative balance gear system was proposed and used to apply different types of dynamic loadings on a model OWT. Test results indicated that the natural frequency of the OWT in sand would increase as the number of applied cyclic loading went up, but the increasing rate of the frequency gradually decreases with the strain accumulation of soil around the monopile. This kind of the frequency change of OWT is thought to be dependent on the way how the OWT is cyclically loaded and the shear strain level of soil in the area adjacent to the pile foundation. In this paper, all test results were plotted in a nondimensional manner in order to be scaled up to predict the consequences for prototype OWT in sandy seabed.

Implementation of Computational Methods to Obtain Accurate Induction Factors for Offshore Wind Turbines

2014 ◽  
Author(s):  
Anand Bahuguni ◽  
Krishnamoorthi Sivalingam ◽  
Peter Davies ◽  
Johan Gullman-Strand ◽  
Vinh Tan Nguyen
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Offshore Wind ◽  
Cfd Simulations ◽  
Sea State ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Blade Tip ◽  
Computational Fluid Dynamics Cfd ◽  
Blade Element

Most of the wind turbine analysis softwares widely being used in the market are based on the Blade Element Momentum method (BEM). The two important parameters that the BEM codes calculate are the axial and the tangential induction factors. These factors are calculated based on the empirical blade lift coefficient Cl and drag coefficient Cd along with some loss/correction functions to account for the losses near the blade tip and the hub. The current study focusses on verifying the values of induction factors using Computational Fluid Dynamics (CFD) simulations for floating offshore wind turbines at a selected sea state. The study includes steady state calculations as well as transient calculations for pitching motions of the turbine due to waves. The NREL FAST software is used to set the simulation scenarios according to OC3 Phase IV cases. The blades are divided a number of elements in CFD calculations and the data are extracted at individual elements to have an exact comparison with the BEM based calculations.

scholarly journals Wind Tunnel Wake Measurements of Floating Offshore Wind Turbines

2017 ◽  
Vol 137 ◽  
pp. 214-222 ◽  
Author(s):  
I. Bayati ◽  
M. Belloli ◽  
L. Bernini ◽  
A. Zasso
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

scholarly journals Assessment of Practical Methods to Predict Accumulated Rotations of Monopile-Supported Offshore Wind Turbines in Cohesionless Ground Profiles

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3915
Author(s):  
Saleh Jalbi ◽  
Joseph Hilton ◽  
Luke Jacques
Keyword(s):  
Wind Turbines ◽  
Time History ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Complex Nature ◽  
Scaled Model ◽  
Offshore Wind Turbines ◽  
Applied Loading ◽  
Number Of Cycles

Monopiles supporting offshore wind turbines can experience permanent non-recoverable rotations (or displacements) during their lifetime due to the cyclic nature of hydrodynamic and aerodynamic loading exerted on them. Recent studies in the literature have demonstrated that conventional cyclic p–y curves recommended in different codes of practice (API-RP-2GEO and DNVGL-RP-C212) may not capture the effects of long-term cyclic loads as they are independent of the loading profile and the number of applied cycles. Several published methodologies based on laboratory scaled model tests (on sands) exist to determine the effect of cyclic lateral loads on the long-term behaviour of piles. The tests vary in terms of the pile behaviour (rigid or flexible pile), number of applied loading cycles, and the load profile (one-way or two-way loading). The best-fit curves provided by these tests offer practical and cost-efficient methods to quantify the accumulated rotations when compared to Finite Element Method. It is therefore desirable that such methods are further developed to take into account different soil types and the complex nature of the loading. The objective of this paper is to compare the performance of the available formulations under the actions of a typical 35-h (hour) storm as per the Bundesamt für Seeschifffahrt und Hydrographie (BSH) recommendations. Using classical rain flow counting, the loading time-history is discretized into load packets where each packet has a loading profile and number of cycles, which then enables the computation of an equivalent number of cycles of the largest load packet. The results show that the loading profile plays a detrimental role in the result of the accumulated rotation. Furthermore, flexibility of the pile also has an important effect on the response of the pile where predictions obtained from formulations based on flexible piles resulted in a much lower accumulated rotation than tests based on rigid piles. Finally, the findings of this paper are expected to contribute in the design and interpretation of future experimental frameworks for Offshore Wind Turbine (OWT) monopiles in sands, which will include a more realistic loading profile, number of cycles, and relative soil to pile stiffness.

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