ASME 2019 2nd International Offshore Wind Technical Conference最新文献

{"title":"Physical Model Testing of the TetraSpar Demo Floating Wind Turbine Prototype","authors":"Mitchell G. Borg, A. Viselli, C. Allen, M. Fowler, Christoffer Sigshøj, Andrea Grech La Rosa, M. T. Andersen, H. Stiesdal","doi":"10.1115/iowtc2019-7561","DOIUrl":"https://doi.org/10.1115/iowtc2019-7561","url":null,"abstract":"\u0000 As part of the process of deploying new floating offshore wind turbines, scale model testing is carried out to de-risk and verify the design of novel foundation concepts. This paper describes the testing of a 1:43 Froude-scaled model of the TetraSpar Demo floating wind turbine prototype that shall be installed at the Metcentre test facility, Norway. The TetraSpar floating foundation concept consists of a floater tetrahedral structure comprising of braces connected together through pinned connections, and a triangular keel structure suspended below the floater by six suspension lines. A description of the experimental setup and program at the Alfond W2 Ocean Engineering Lab at University of Maine is given. The objective of the test campaign was to validate the initial design, and contribute to the development of the final demonstrator design and numerical models. The nonlinear hydrodynamic characteristics of the design are illustrated experimentally and the keel suspension system is shown to satisfy design criteria.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116904032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling the Aerodynamics of a Floating Wind Turbine Model Using a CFD-Based Actuator Disc Method","authors":"Ryan Bezzina, T. Sant, D. Micallef","doi":"10.1115/iowtc2019-7526","DOIUrl":"https://doi.org/10.1115/iowtc2019-7526","url":null,"abstract":"\u0000 Significant research in the field of Floating Offshore Wind Turbine (FOWT) rotor aerodynamics has been documented in literature, including validated aerodynamic models based on Blade Element Momentum (BEM) and vortex methods, amongst others. However, the effects of platform induced motions on the turbine wake development downstream of the rotor plane or any research related to such areas is rather limited. The aims of this paper are two-fold. Initially, results from a CFD-based Actuator Disc (AD) code for a fixed (non-surging) rotor are compared with those obtained from a Blade Element Momentum (BEM) theory, as well as previously conducted experimental work. Furthermore, the paper also emphasises the effect of tip speed ratio (TSR) on the rotor efficiency. This is followed by the analysis of floating wind turbines specifically in relation to surge displacement, through an AD technique implemented in CFD software, ANSYS Fluent®. The approach couples the Blade Element Theory (BET) for estimating rotating blade loads with a Navier Stokes solver to simulate the turbine wake.\u0000 With regards to the floating wind turbine cases, the code was slightly altered such that BET was done in a transient manner i.e. following sinusoidal behaviour of waves. The AD simulations were performed for several conditions of TSRs and surge frequencies, at a constant amplitude. Similar to the fixed rotor analysis, significant parameters including thrust and power coefficients, amongst others, were studied against time and surge position. The floating platform data extracted from the AD approach was compared to the non-surging turbine data obtained, to display platform motion effects clearly. Data from hot wire near wake measurements and other simulation methods were also consulted.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117009977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on Underwater Vehicle for Monitoring of Offshore Wind Generation Systems","authors":"I. Yamamoto, Akihiro Morinaga, M. Lawn","doi":"10.1115/iowtc2019-7506","DOIUrl":"https://doi.org/10.1115/iowtc2019-7506","url":null,"abstract":"A compact low cost lightweight ROV (Remotely operated underwater vehicle) has been developed to assist in the monitoring of offshore wind generation systems. The ROV successfully dove 76 meters to check the condition of the spa to the base and associated moorings of a floating offshore wind generator (Goto, Nagasaki, Japan). An abundance of sea life was also observed around the base as the base provides a kind of artificial reef which fosters a marine ecosystem. The design philosophy of this ROV and overall system are described in this paper including the proposed addition of robotic arms.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129001627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WindCrete Fatigue Verification","authors":"P. Trubat, J. Bairán, A. Yagüe, C. Molins","doi":"10.1115/iowtc2019-7564","DOIUrl":"https://doi.org/10.1115/iowtc2019-7564","url":null,"abstract":"\u0000 WindCrete is an offshore concrete spar type platform for Wind Turbines developed at Universitat Politècnica de Catalunya – BarcelonaTech. The main characteristics of the platform are its monolithic configuration and the use of concrete as main material. The monolithic nature allows avoiding joints between the substructure and the tower increasing the service life of the structure. The use of concrete increases the resistance when exposed to an offshore environment but requires ensuring a full compression state along the structure to avoid cracking. Thus, the platform is post-tensioned by longitudinal tendons along its length.\u0000 Adequate fatigue design is a key factor to ensure the reliability of offshore structures. Floating Offshore Wind Turbines are subjected to cyclic phenomena coming from waves, wind, rotor-induced vibrations and structural vibrations. These loads have to be considered in order to assess the fatigue life of offshore structures. Furthermore, pre-stressed concrete adds an internal load such that it avoids the presence of tension stresses at any given section, which has a positive influence on the fatigue response of the structure by increasing its fatigue resistance. An excess of compression can, however, also induce an adverse effect on the fatigue resistance of the concrete.\u0000 In order to study the fatigue behaviour of WindCrete when fitted with a 5MW Wind Turbine, a Fatigue Limit State verification is performed according to the DNVGL-ST-0437 for load cases definition and FIB Model Code (2010) for fatigue structural verification. The location chosen to install WindCrete is the Gulf de Lion, at the west of the Mediteranian Sea off the coast of Catalunya with a mean wind speed above 9 m/s. The metocean conditions for design purpose are presented, which are obtained from available environmental data.\u0000 A total of 458 simulation cases are performed using the NREL FAST software assuming wind and wave co-directionally, and quasi-static mooring response for Parked and Power-Production operational modes. Assuming an elastic response of the tower, the internal stresses at the tower base are obtained for all the simulations. Then, a fatigue analysis is performed at the tower base through a cumulative damage approach based on the Palmgren-Miner rule. The analysis accounted for the multiaxial stresses produced by the combination of axial, bending and tangential forces. The S-N material curves were defined according to the Model Code 2010 method, which accounts for the effect of the stress range as well as the average stress.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124542952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Modified Free-Wake Vortex Ring Model for the Aerodynamics of Floating Offshore Wind Turbines","authors":"Jing Dong, A. Viré, Simao Ferreira, Zhang-rui Li, G. V. Bussel","doi":"10.1115/iowtc2019-7610","DOIUrl":"https://doi.org/10.1115/iowtc2019-7610","url":null,"abstract":"\u0000 A modified free-wake vortex ring model is proposed to compute the dynamics of a floating horizontal-axis wind turbine. The model is divided into two parts. The near wake model uses a blade bound vortex model and trailed vortex model, which is developed based on vortex filament method. By contrast, the far wake model is based on the vortex ring method. This is a good compromise between accuracy and computational cost. In this work, the model is used to assess the influence of floating platform motions on the performance of a horizontal-axis wind turbine rotor. The results are validated on the 5MW NREL rotor and compared with other vortex models for the same rotor subjected to different platform motions. It was found that the result from the proposed method are more reliable than the results from BEM theory especially at small angles of attack in the region of low wind speeds, on the one hand, and high wind speeds with blade pitch motions, on the other hand.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116917797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of an Offshore Wind Turbine Using a Weakly-Compressible CFD Solver Coupled With a Blade Element Turbine Model","authors":"B. Elie, G. Oger, D. L. Touzé","doi":"10.1115/iowtc2019-7600","DOIUrl":"https://doi.org/10.1115/iowtc2019-7600","url":null,"abstract":"\u0000 The present study addresses the first steps of development and validation of a coupled CFD-BE (Blade Element) simulation tool dedicated to offshore wind turbine farm modelling. The CFD part is performed using a weakly-compressible solver (WCCH). The turbine is taken into account using FAST (from NREL) and its effects are imposed into the fluid domain through an actuator line model. The first part of this paper is dedicated to the presentation of the WCCH solver and its coupling with the aero-elastic modules from FAST. In a second part, for validation purposes, comparisons between FAST and the WCCH-FAST coupling are presented and discussed. Finally, a discussion on the performances, advantages and limitations of the formulation proposed is provided.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122380792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid Model Tests for Floating Offshore Wind Turbines","authors":"M. Thys, A. Fontanella, F. Taruffi, M. Belloli, Petter A. Berthelsen","doi":"10.1115/iowtc2019-7575","DOIUrl":"https://doi.org/10.1115/iowtc2019-7575","url":null,"abstract":"\u0000 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.\u0000 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.\u0000 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.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"53 86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131127960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Nacelle Drag on the Performance of a Floating Wind Turbine Platform","authors":"Daewoong Son, Pauline Louazel, Bingbin Yu","doi":"10.1115/iowtc2019-7595","DOIUrl":"https://doi.org/10.1115/iowtc2019-7595","url":null,"abstract":"\u0000 Wind forces acting on an offshore wind turbine are transferred to the bottom of the tower and consequently to the floating structure. Thus, drag forces acting on each component of the wind turbine such as the blades, the nacelle, and the tower must be accounted for properly in order to evaluate the performance of the supporting platform. In the aero-elastic wind turbine simulation tool FAST v.7, the nacelle drag component, however, has not been implemented, which means that only the drag forces on the tower and on the blades are represented. In this work, the front and side nacelle drag forces are modelled in FAST v.7 via different drag contributions. This paper will examine the behavior of a floating offshore semisubmersible platform, the WindFloat, for different Rotor-Nacelle-Assembly (RNA) yaw-misalignments with emphasis on the nacelle drag component.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115898272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrating Compressed Air Energy Storage (CAES) in Floating Offshore Wind Turbines","authors":"Peter P. Vella, T. Sant, R. Farrugia","doi":"10.1115/iowtc2019-7533","DOIUrl":"https://doi.org/10.1115/iowtc2019-7533","url":null,"abstract":"\u0000 The design of an offshore energy storage system carries unknowns which need to be studied at an early stage of the project to avoid unnecessary costs of failures. These risks have led to an increasing dependence on more sophisticated mathematical models.\u0000 This paper refers specifically to energy storage in the offshore wind farming industry and has the objective of proposing an adiabatic compressed air energy (A-CAES) system which would be integrated on a semi-submersible offshore wind turbine (OWT) platform. Calculations in respect to the sizing of the main sub-components of the system are included and estimates for the overall round trip efficiency are presented.\u0000 Preliminary calculations to size the various parts of the energy storage system (ESS) have been carried out based on the energy availability of an offshore 8 MW wind turbine with real wind data from the North Sea. The load data to determine the lowest 12-hour demand period was taken from the Nordpool database. The calculations of the proposed conceptual design are based on an operational scenario in which the 24-hour period of a particular day is split in a 12-hour charging and 12-hour discharging cycle. For charging, a 5-bank, 2-stage compressor train is used to pressurize a number of steel cylindrical vessels with compressed air. This is followed by a process in which the compressed air is discharged across 12 hours using a 2-bank, 2-stage expander turbine. The multiple compression banks enable a modular power delivery to the air storage vessels, with the number of compressors utilized varying subject to wind availability. The two stages allowed for the air to be cooled in between the stages using heat exchangers, transferring the heat of compression to a pressurized sea water circuit. The hot water would be stored in thermally insulated vessels at 350°C to heat the inlet expanding air in the discharge period. A 70 and 100 Bar charging scenarios, both with a cushion pressure (CP) in the air storage vessel (ASV) of 10 Bar at the end of the discharge cycle have been considered.\u0000 Standard performance criteria are calculated such as compression and expansion ratios, inlet and outlet temperatures for the respective expansion and compression air streams and flow rates within the heat exchangers to come up with an indicative sizing proposal for the respective turbo machinery and storage vessels making up the system. Round trip efficiencies are also calculated.\u0000 The study determined that a CAES system consisting of 9 compressed air storage vessels operating with a peak pressure of 100 Bar should meet the storage requirements. It is also estimated that the entire CAES system would require around 1082 m2 of deck area on the platform to accommodate the pressure vessels, the compressor and expander trains, the heat exchanger and the hot water storage vessel.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121665725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damping Identification of the TetraSpar Floater in Two Configurations With Operational Modal Analysis","authors":"A. Pegalajar-Jurado, Freddy J. Madsen, H. Bredmose","doi":"10.1115/iowtc2019-7623","DOIUrl":"https://doi.org/10.1115/iowtc2019-7623","url":null,"abstract":"\u0000 Second-order hydrodynamic loads can induce motions at the natural frequencies of a floating wind turbine. These resonant responses are highly dependent on the hydrodynamic damping, which is mostly introduced by viscous effects. Numerically, these viscous effects are often represented by a Morison drag term with relative velocity, which introduces forcing, sea state-dependent linear damping and amplitude-dependent quadratic damping. Recent literature shows that calibration of the Morison drag coefficients to decay tests is not sufficient to achieve an accurate response in the numerical models. In addition, calibration of the drag coefficient alone changes both forcing and damping. Hence, following common practice, additional damping terms are needed, which require calibration against operating conditions. In this study, we apply Operational Modal Analysis (OMA) to wave basin results for the TetraSpar floater of Stiesdal Offshore Technologies. The floater was tested at scale 1:60 with the DTU 10MW reference wind turbine, both in the semi and spar configurations. We identify the linearized damping ratio in surge and pitch for different environmental conditions and investigate its dependency on the sea state and the motion amplitude. Our preliminary results show that the damping of the pitch mode follows increasing trends with significant wave height and motion amplitude, whereas the damping in surge presents a less clear tendency. This is linked to the larger damping level, smaller natural frequency and larger OMA uncertainty for surge. The paper concludes with a discussion of the dependency of OMA estimates on the amount of data and its processing.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132453522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}