1,720,981 research outputs found
A large-scale wind turbine model installed on a floating structure:experimental validation of the numerical design
Full text linkIn the field of floating wind energy, large-scale wind turbine models deployed in natural environments represent a key link between small-scale laboratory tests and full-scale prototypes. While implying smaller cost, design and installation effort than a full-scale prototype, large-scale models are technologically very similar to prototypes, can be tested in natural sea and wind conditions, and reduce by a consistent amount the dimensional scaling issues arising in small-scale experiments. In this framework the presented work report the aerodynamic and control system assessment of a 1:15 model of the DTU 10 MW wind turbine installed on a multipurpose-platform model for fish farming and energy production. The model has operated for 6 months in a natural laboratory and has been exposed to fully natural and uncontrolled environmental conditions. Assessment is performed in terms of rotor thrust force and power controller parameters such as rotor speed, blade pitch and rotor power as a function of incoming wind speed
Analysis of FOWT dynamics in 2-DOF hybrid HIL wind tunnel experiments
Full text linkThis paper presents the main results of experimental hybrid/HIL wind tunnel tests of the National Renewable Energy Laboratory (NREL) 5 MW wind turbine coupled with the DeepCwind semi-submersible floating platform. Experiments in still water and in irregular waves without wind are compared to corresponding FAST simulations in order to assess the effectiveness of the proposed HIL methodology and to highlight the main sources of uncertainty. Tests are repeated under three wind conditions, corresponding to different wind turbine operating points, to evaluate the effect of the aerodynamic force field on the overall system response. Experimental results are compared to the output of FAST simulations to investigate its prediction capability with respect to the influence of unsteady aerodynamic loads on the FOWT dynamics
Variable-speed Variable-pitch control for a wind turbine scale model
Full text linkThe present work deals with the issues faced by authors in the implementation of a variable-speed variable-pitch (VS-VP) controller on a wind turbine scale model for wind tunnel tests. The PoliMi 1/75 model of the DTU 10MW reference wind turbine (RWT) is presented, focusing on the mechatronic system used to control the machine. The main differences between the PoliMi wind turbine model (WTM) and the DTU 10MW RWT are highlighted out pointing out their influence on the behavior of the controlled machine. Then, the control logic adopted for the PoliMi WTM is introduced. Finally, results from wind tunnel tests on the controlled model are shown and the performance of the closed-loop system is discussed
Experimental validation of the aero-servo design of a large-scale floating offshore wind turbine model
No full textOffshore floating wind turbines are such complex systems from the point of view of global dynamics that numerical models are often insufficient in describing completely and correctly their behavior. In this framework large scale models deployed in a natural outdoor environment are a valid complement in understanding the real features of the system and in updating or validating codes. In the case of wind turbines adopting a large scale allows to better reproduce the aerodynamic behavior of the rotor. Objective of the present work is the validation of the aerodynamic design of a large-scale 1:15 model of the DTU 10 MW wind turbine deployed on a multipurpose floating platform, built in the framework of the Horizon 2020 project termed as "The Blue Growth Farm Project". It is requested to assess the effective aerodynamic characteristics of the rotor so to understand if the physical design is well respecting the aerodynamic properties requested in the design phase. Particular care is put in the correct reproduction of the operating parameters as part of the assessment of the control system. For initial analysis a good compliance between design and physical model is found. Regarding the aerodynamic characteristics, a good agreement between the experimental Cp values and the numerical curves is observed. Overall, the physical rotor aerodynamic design is validated and the power controller steady-state performances are assessed
Numerical and experimental wind tunnel analysis of aerodynamic effects on a semi-submersible floating wind turbine response
Full text linkThis paper presents the main results of an experimental campaign about the DeepCwind semi-submersible floating offshore wind turbine (FOWT), that was carried out at Politecnico di Milano wind tunnel, adopting a hybrid hardware-in-the-loop (HIL) testing technique. Differently from previous works by the authors, this further analysis herein reported, is specifically focused on evaluating the effects of aerodynamic loads on the FOWT platform motions. In order to reproduce the FOWT response to combined wind and waves in a wind tunnel, exploiting the high-quality flow, a HIL system was used. The aerodynamic and rotor loads were reproduced by means of a wind turbine scale model operating inside the wind tunnel and were combined with numerically generated wave loads for real-time integration of the FOWT rigid-body motion equations. The resulting platform motions were imposed to the wind turbine scale model by a hydraulic actuation system. A series of HIL tests was performed to assess the rotor loads effect on the FOWT response. Free-decay tests in still water under laminar un-sheared wind were carried out to evaluate how the aerodynamic forcefield modifies the platform modes frequency and damping. Irregular wave tests for different steady winds were performed to investigate the dependency of platform motion from the wind turbine operating conditions. A FAST v8 model of the studied floating system was developed to support the analysis and numerical simulations were performed to reproduce environmental conditions equivalent to those of the experimental tests. The FAST model prediction capability is discussed against HIL wind tunnel tests results
Large aeroelastic model of a floating offshore wind turbine: Mechanical and mechatronics design
No full textThis paper deals with the mechatronic design of a large-scale wind turbine model (outdoor scaled prototype) based on the DTU 10MW. This is going to be integrated in the model of a multi-purpose floating structure to be deployed at the Natural Ocean Engineering Laboratory (NOEL) in Reggio Calabria (Italy). The floating wind turbine model is the downscaling of the full-scale structure designed within the EU H2020 Blue Growth Farm project. The structural design of the scaled wind turbine is presented, starting from the aeroelastic and aerodynamic design carried out in a previous work
A 6-dofs hardware-in-the-loop system for wind tunnel tests of floating offshore wind turbines
No full textThis article presents a hardware-in-the-loop (HIL) methodology developed at Politecnico di Milano (PoliMi) to perform wind tunnel tests on floating offshore wind turbines (FOWTs). The 6-DOFs HIL setup is presented, focusing on the main differences with respect to a previous 2-DOFs system. Aerodynamic, rotor and control related loads, physically reproduced by the wind turbine scale model, must be measured in real-time and integrated with the platform numerical model. These forces contribute to couple wind turbine and floating platform dynamics and their correct reproduction is of fundamental importance for the correct simulation of the floating system behavior. The procedure developed to extract rotor loads from the available measurements is presented, discussing its limitations and the possible uncertainties introduced in the results. Results from verification tests in no-wind conditions are presented and analyzed to identify the main uncertainty sources and quantify their effect on the reproduction of the floating wind turbine response to combined wind and waves
Experimental validation of a wave elevation observer on a floating wind turbine model
No full textThe scope of this work is to investigate if and how it is possible to estimate the incident wave elevation on a floating wind turbine, with the purpose of improved control strategies. A Kalman based algorithm is proposed, which receives as input the rigid motions of the floater and estimates the wave elevation hitting the floating platform. The structure of the observer is described and the estimator is tested numerically on the OC3-Hywind platform coupled with the 5-MW reference wind turbine from NREL. Limitations to the estimation procedure are discussed. Finally the algorithm is tested on experimental data coming from a wave basin experimental campaign on a floating wind turbine model. The algorithm still needs improvements, but results are encouraging in the development of this technology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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