Tor Anders Nygaard

• Mian, Haris Hameed; Siddiqui, Muhammad Salman; Franchina, Nicoletta; Kouaissah, Otman; Wang, Gang & Nygaard, Tor Anders (2024). Aerodynamic and Structural Assessment of Floating Wind Turbine Rotor Under Varying Tilt Angle. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 2767. doi: 10.1088/1742-6596/2767/2/022053. Full text in Research Archive Show summary

  Predicting the aerodynamic performance of floating offshore wind turbines (FOWTs) proves challenging due to platform motion induced by waves. The effect of wind and waves results in a six-degree-of-freedom motion of the platform, directly influencing turbine performance. Understanding the impact of specific degrees of freedom (DOF) motions on aerodynamics and structural response is crucial for effective wind turbine design. This research examines the impact of rotor tilt on both aerodynamic performance and structural response. The investigation employs computational fluid dynamics (CFD) analysis and mapping aerodynamic loads onto the finite element (FE) mesh for structural analysis. The study employs a comprehensive 3D simulation, utilizing the moving reference frame (MRF) method for the NREL 5 MW reference wind turbine CFD simulations. It explores different rotor tilt angles (5°, 10°, 15°, and 20°) encountered by offshore structures during their operation and examines their impact on aerodynamic performance. Predicted aerodynamic loads were mapped onto the blade FE mesh using the radial basis function (RBF) interpolation technique and solved using the open-source FE solver CalculiX. The analysis shows that the turbine performance is relatively unaffected up to a tilt angle of 10°. However, further increase in rotor tilt angle adversely impacts turbine performance, leading to notable reductions in thrust and power output. The fluid-structure coupled analysis provided insights into the deformations and stresses experienced by the turbine blade, indicating a notable increase in flap-wise displacement for larger tilt angles, while edge-wise displacement is not as significantly affected. The maximum stress location on the blade generally correlates well with actual observations.

• Bergua, Roger; Robertson, Amy; Jonkman, Jason; Branlard, Emmanuel; Fontanella, Alessandro & Belloli, Marco [Show all 62 contributors for this article] (2023). OC6 project Phase III: validation of the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure. Wind Energy Science. ISSN 2366-7443. 8(4), p. 465–485. doi: 10.5194/wes-8-465-2023. Full text in Research Archive
• Sakaris, Christos; Schlanbusch, Rune; Nygaard, Tor Anders; Sakellariou, John S. & Tutkun, Murat (2023). Statistical Times Series Based Damage Detection in the Fiber Rope Mooring Lines of the Semi-Submersible OO-STAR Wind Floater. In Aghdam, Amir (Eds.), IEEE 62nd Conference on Decision and Control (CDC 2023). IEEE (Institute of Electrical and Electronics Engineers). ISSN 9798350301243. p. 4861–4866. doi: 10.1109/CDC49753.2023.10383638. Full text in Research Archive
• Page, Ana M.; Næss, Veronika; Vaal, Jacobus Bernardus De; Eiksund, Gudmund Reidar & Nygaard, Tor Anders (2019). Impact of foundation modelling in offshore wind turbines: Comparison between simulations and field data. Marine Structures. ISSN 0951-8339. 64, p. 379–400. doi: 10.1016/j.marstruc.2018.11.010. Full text in Research Archive Show summary

  The design of Offshore Wind Turbines (OWTs) relies on integrated simulation tools capable of predicting the system dynamic characteristics and the coupled loads and responses. Despite allefforts to develop accurate integrated models, these often fail to reproduce the measured naturalfrequencies, partly due to the modelling of the foundation. Several foundation models and ca-libration approaches have been proposed and compared with small or large scale field tests,where only the soil and the foundation are included. However, there is a lack of more integralvalidation where the interaction between the foundation and the structure is taken into account.The paper investigates the impact of the foundation model and calibration approach on the si-mulated response of a monopile-based OWT installed in the North Sea by comparing simulationsand full-scale field data. The OWT structure and the environmental actions are implemented inthe aero-servo-hydro-elastic code 3DFloat. Two foundation models and two calibration ap-proaches are evaluated. The results indicate that, with a conceptually correct foundation modeland a realistic calibration, it is possible to match the measured natural frequency and predictaccurate fatigue loads. More accurate predicted loads will reduce uncertainties in the estimatedfatigue lifetime and therefore reduce risk in the design

• Pierella, Fabio; Bredmose, Henrik; Vaal, Jacobus Bernardus De; Eliassen, Lene; Krokstad, Jørgen R & Nygaard, Tor Anders [Show all 8 contributors for this article] (2018). The Dimensioning Sea Loads (DIMSELO) project. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 1104(1). doi: 10.1088/1742-6596/1104/1/012037. Full text in Research Archive Show summary

  DIMSELO is a Competence Building for Industry project (KPN), granted by the Norwegian Research Council under the ENERGIX program, which ran from 2013 to 2017. The project's objective was to quantify the consequences of using advanced sea loads modeling in integrated simulations of offshore wind turbines in shallow to intermediate waters. During the project, engineering hydrodynamics load and wave kinematics models of increasing complexity and fidelity were chosen from the literature and implemented. The effect of different model combinations on the substructure loads was was tested for three reference turbines: a DTU 10 MW rotor positioned on a monopile at a water depth of h = 25 m, on a second monopile at h = 35 m and on a jacket, also at h = 35 m. In this paper, the fatigue loads in a production case for the h = 25 m monopile was calculated via three different load models: the well-known Morison model, the Rainey nonlinear force model and the McCamy-Fuchs linear diffraction model. The models were coupled to kinematics coming both from linear irregular waves and second order irregular waves. The comparison showed that using the McCamy-Fuchs diffraction theory reduced the predicted fatigue damage by 15% with respect to a base case where the Morison load model was used. Nonlinear wave kinematics and nonlinear force models influenced the force calculations but did not alter the total fatigue damage, since the load cases with high wave steepness were less likely to happen.

• Skau, Kristoffer Skjolden; Page, Ana M.; Kaynia, Amir M.; Løvholt, Finn; Norén-Cosgriff, Karin & Sturm, Hendrik [Show all 13 contributors for this article] (2018). REDWIN – REDucing cost in offshore WINd by integrated structural and geotechnical design. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 1104(1). doi: 10.1088/1742-6596/1104/1/012029. Full text in Research Archive Show summary

  The cost of offshore wind energy production has to be reduced continuously to improve its competitiveness compared to other energy sources. To contribute to this goal, a 4- year research project REDWIN – REDucing cost of offshore WINd by structural and geotechnical integrated design – is currently ongoing, addressing the challenge of integrating the geotechnical discipline in the design process. The project aims to develop foundation and soil models to be used in dynamic time-domain analyses of offshore wind turbine structures. A library of models has been developed for representation of the most common foundation types. The models can be applied to different ground conditions by site-specific model input. To make the models applicable for practical usage, it has been important to balance the need for computational effectiveness against the need for accuracy. Studies so far indicate that the foundation models improve the accuracy in the integrated analyses.

• Oggiano, Luca; Pierella, Fabio; Nygaard, Tor Anders; Vaal, Jacobus Bernardus De & Arens, Emile (2017). Reproduction of steep long crested irregular waves with CFD using the VOF method. Energy Procedia. 137, p. 273–281. doi: 10.1016/j.egypro.2017.10.351. Full text in Research Archive
• Pierella, Fabio; Stenbro, Roy; Oggiano, Luca; Vaal, Jacobus Bernardus De; Nygaard, Tor Anders & Krokstad, Jørgen R (2017). Stream function wave embedment into linear irregular seas: A new method based on the Hilbert transform. ISOPE - International Offshore and Polar Engineering Conference. Proceedings. ISSN 1098-6189. p. 412–419. Full text in Research Archive
• Aasen, Steffen; Page, Ana M.; Skau, Kristoffer Skjolden & Nygaard, Tor Anders (2017). Effect of foundation modelling on the fatigue lifetime of a monopile-based offshore wind turbine. Wind Energy Science. ISSN 2366-7443. 2(2), p. 361–376. doi: 10.5194/wes-2-361-2017. Full text in Research Archive Show summary

  Several studies have emphasized the importance of modelling foundation response with representative damping and stiffness characteristics in integrated analyses of offshore wind turbines (OWTs). For the monopile foundation, the industry standard for pile analysis has shown to be inaccurate, and alternative models that simulate foundation behaviour more accurately are needed. As fatigue damage is a critical factor in the design phase, this study investigates how four different soil-foundation models affect the fatigue damage of an OWT with a monopile foundation. This study shows how both stiffness and damping properties have a noticeable effect on the fatigue damage, in particular for idling cases. At mud-line, accumulated fatigue damage varied up to 22 % depending on the foundation model used.

• Oggiano, Luca; Pierella, Fabio; Vaal, Jacobus Bernardus De; Nygaard, Tor Anders; Stenbro, Roy & Arens, Emile (2017). Modeling of 2D irregular waves on a sloped bottom using a fully nonlinear Navier-Stokes/VOF formulation. ISOPE - International Offshore and Polar Engineering Conference. Proceedings. ISSN 1098-6189. p. 622–629. Full text in Research Archive
• Azcona, José; Munduate, Xabier; González, Leo & Nygaard, Tor Anders (2017). Experimental validation of a dynamic mooring lines code with tension and motion measurements of a submerged chain. Ocean Engineering. ISSN 0029-8018. 129, p. 415–427. doi: 10.1016/j.oceaneng.2016.10.051. Full text in Research Archive
• Azcona, José; Palacio, David; Munduate, Xabier; González, Leo & Nygaard, Tor Anders (2017). Impact of mooring lines dynamics on the fatigue and ultimate loads of three offshore floating wind turbines computed with IEC 61400-3 guideline. Wind Energy. ISSN 1095-4244. 20(5), p. 797–813. doi: 10.1002/we.2064. Full text in Research Archive
• Oggiano, Luca; Pierella, Fabio; Vaal, Jacobus Bernardus De; Nygaard, Tor Anders; Stenbro, Roy & Arens, Emile (2016). Comparison of experiments, CFD simulations and a finite element code on a stiff monopile in shallow water under shoaling regular waves. ISOPE - International Offshore and Polar Engineering Conference. Proceedings. ISSN 1098-6189. 2016-January, p. 219–227. Full text in Research Archive
• Vaal, Jacobus Bernardus De; Nygaard, Tor Anders & Stenbro, Roy (2016). Developing a passive load reduction blade for the DTU 10 MW reference turbine. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 753. doi: 10.1088/1742-6596/753/4/042004. Full text in Research Archive
• Nygaard, Tor Anders; Vaal, Jacobus Bernardus De; Pierella, Fabio; Oggiano, Luca & Stenbro, Roy (2016). Development, verification and validation of 3DFloat; aero-servo-hydro-elastic computations of offshore structures. Energy Procedia. 94, p. 425–433. doi: 10.1016/j.egypro.2016.09.210. Full text in Research Archive
• Oggiano, Luca; Pierella, Fabio; Nygaard, Tor Anders; Vaal, Jacobus Bernardus De & Arens, Emile (2016). Comparison of Experiments and CFD Simulations of a Braceless Concrete Semi-submersible Platform. Energy Procedia. 94, p. 278–289. doi: 10.1016/j.egypro.2016.09.184. Full text in Research Archive
• Robertson, Amy N.; Wendt, Fabian; Jonkman, Jason M.; Popko, Wojciech; Borg, Michael & Bredmose, H. [Show all 25 contributors for this article] (2016). OC5 Project Phase Ib: Validation of Hydrodynamic Loading on a Fixed, Flexible Cylinder for Offshore Wind Applications. Energy Procedia. 94, p. 82–101. doi: 10.1016/j.egypro.2016.09.201. Full text in Research Archive Show summary

  This paper summarizes the findings from Phase Ib of the Offshore Code Comparison, Collaboration, Continued with Correlation (OC5) project. OC5 is a project run under the International Energy Agency (IEA) Wind Research Task 30, and is focused on validating the tools used for modelling offshore wind systems through the comparison of simulated responses of select offshore wind systems (and components) to physical test data. For Phase Ib of the project, simulated hydrodynamic loads on a flexible cylinder fixed to a sloped bed were validated against test measurements made in the shallow water basin at the Danish Hydraulic Institute (DHI) with support from the Technical University of Denmark (DTU). The first phase of OC5 examined two simple cylinder structures (Phase Ia and Ib) to focus on validation of hydrodynamic models used in the various tools before moving on to more complex offshore wind systems and the associated coupled physics. Verification and validation activities such as these lead to improvement of offshore wind modelling tools, which will enable the development of more innovative and cost-effective offshore wind designs.

• Myhr, Anders & Nygaard, Tor Anders (2015). Comparison of Experimental Results and Computations for Tension-Leg-Buoy Offshore Wind Turbines. Journal of Ocean and Wind Energy. ISSN 2310-3604. 2(1), p. 12–20. Full text in Research Archive
• Oggiano, Luca; Arens, Emile; Myhr, Anders; Nygaard, Tor Anders & Evans, Steve (2015). CFD simulations on a tension leg buoy platform for offshore wind turbines and comparison with experiments, Proceedings of the twenty-fifth International Ocean and Polar Engineering Conference - ISOPE 2015. International Society of Offshore & Polar Engineers. ISSN 9781880653890. p. 309–315. Full text in Research Archive
• Myhr, Anders & Nygaard, Tor Anders (2014). Experimental Results for Tension-Leg-Buoy Offshore Wind Turbine Platforms. Journal of Ocean and Wind Energy. ISSN 2310-3604. 1(4), p. 217–224. Full text in Research Archive
• Azcona, José; Bouchotrouch, Faisal; Gonzalez, Marta; Garciandia, Joseba; Munduate, Xavier & Kelberlau, Felix [Show all 7 contributors for this article] (2014). Aerodynamic thrust modelling in wave tank tests of offshore floating wind turbines using a ducted fan. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 524:012089. doi: 10.1088/1742-6596/524/1/012089. Full text in Research Archive
• Azcona, José; Bouchotrouch, Faisal; Gonzalez, Marta; Garciandia, Joseba; Munduate, Xabier & Kelberlau, Felix [Show all 7 contributors for this article] (2014). Aerodynamic Thrust Modelling in Wave Tank Tests of Offshore Floating Wind Turbines Using a Ducted Fan. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 524. Full text in Research Archive
• Popko, Wojciech; Vorpahl, Fabian; Zuga, Adam; Kohlmeier, Martin; Jonkman, Jason & Robertson, Amy [Show all 27 contributors for this article] (2014). Offshore Code Comparison Collaboration Continuation (OC4), Phase I—Results of coupled simulations of an offshore wind turbine with jacket support structure. Journal of Ocean and Wind Energy. ISSN 2310-3604. 1(1), p. 1–11. Full text in Research Archive Show summary

  In this paper, the exemplary results of the IEA Wind Task 30 Offshore Code Comparison Collaboration Continuation (OC4) Project – Phase I, focused on the coupled simulation of an offshore wind turbine (OWT) with a jacket support structure, are presented. The focus of this task has been the verification of OWT modeling codes through code-to-code comparisons. The discrepancies between the results are shown and the sources of the differences are discussed. The importance of the local dynamics of the structure is depicted in the simulation results. Furthermore, attention is given to aspects such as the buoyancy calculation and methods of accounting for additional masses (i.e., hydrodynamic added mass). Finally, recommendations concerning the modeling of the jacket are given.

• Raadal, Hanne Lerche; Vold, Bjørn Ivar; Myhr, Anders & Nygaard, Tor Anders (2014). GHG emissions and energy performance of offshore wind power. Renewable Energy. ISSN 0960-1481. 66, p. 314–324. doi: 10.1016/j.renene.2013.11.075. Full text in Research Archive
• Myhr, Anders; Bjerkseter, Catho; Ågotnes, Anders & Nygaard, Tor Anders (2014). Levelised cost of energy for offshore floating wind turbines in a lifecycle perspective. Renewable Energy. ISSN 0960-1481. 66, p. 714–728. doi: 10.1016/j.renene.2014.01.017. Full text in Research Archive
• Myhr, Anders & Nygaard, Tor Anders (2012). Load reductions and optimizations on tension-leg-buoy offshore wind turbine platforms. ISOPE - International Offshore and Polar Engineering Conference. Proceedings. ISSN 1098-6189. 1, p. 232–239. Full text in Research Archive
• Popko, W.; Vorpahl, F.; Zuga, A.; Kohlmeier, M.; Jonkman, J. & Robertson, A. [Show all 26 contributors for this article] (2012). Offshore Code Comparison Collaboration Continuation (OC4), Phase I - Results of Coupled Simulation of Offshore Wind Turbine with Jacket Support Structure. In Chung, Jin S.; Langen, Ivar; Hong, Sa Young & Prinsenberg, Simon J. (Ed.), Proceedings of the Twenty-second (2012) International Offshore and Polar Engineering Conference. International Society of Offshore & Polar Engineers. ISSN 9781880653944. p. 337–346. Full text in Research Archive
• Myhr, Anders; Maus, Karl Jacob & Nygaard, Tor Anders (2011). Experimental and computational comparisons of the OC3-HYWIND and Tension-Leg-Buoy (TLB) floating wind turbine conceptual designs, Proceedings of the Twenty-First (2011) International Offshore and Polar Engineering Conference. International Society of Offshore & Polar Engineers. ISSN 9781880653968. p. 353–360. Full text in Research Archive
• Jonkman, Jason; Nygaard, Tor Anders; Maus, Karl Jacob; Larsen, Torben J.; Hansen, Anders Melchior & Karimirad, Madjid [Show all 15 contributors for this article] (2010). Offshore Code Comparison Collaboration within IEA Wind Task 23: Phase IV Results Regarding Floating Wind Turbine Modeling. OFFSHORE: TOOLS, SUPPORT STRUCTURES, Proceedings of the European wind energy conference & exhibition (EWEC 2010). EWEA. Full text in Research Archive Show summary

  Offshore wind turbines are designed and analyzed using comprehensive simulation codes that account for the coupled dynamics of the wind inflow, aerodynamics, elasticity, and controls of the turbine, along with the incident waves, sea current, hydrodynamics, and foundation dynamics of the support structure. This paper describes the latest findings of the code-to-code verification activities of the Offshore Code Comparison Collaboration, which operates under Subtask 2 of the International Energy Agency Wind Task 23. In the latest phase of the project, participants used an assortment of codes to model the coupled dynamic response of a 5-MW wind turbine installed on a floating spar buoy in 320 m of water. Code predictions were compared from load-case simulations selected to test different model features. The comparisons have resulted in a greater understanding of offshore floating wind turbine dynamics and modeling techniques, and better knowledge of the validity of various approximations. The lessons learned from this exercise have improved the participants? codes, thus improving the standard of offshore wind turbine modeling.

• Lim, Joon; Nygaard, Tor Anders; Strawn, Roger & Potsdam, Mark (2007). Blade-Vortex Interaction Airloads Prediction Using Coupled Computational Fluid and Structural Dynamics. Journal of the American Helicopter Society. ISSN 0002-8711. 54(2). Full text in Research Archive
• Nygaard, Tor Anders & Meakin, Robert L. (2004). Aerodynamic Analysis of a Spinning Missile with Dithering Canards. Journal of Spacecraft and Rockets. ISSN 0022-4650. 41(5), p. 726–734. doi: 10.2514/1.13075. Full text in Research Archive
• Pielke, Roger A.; Nichols, Mel; Walko, Robert; Nygaard, Tor Anders & Zeng, X (1997). Several Unresolved Issues in Numerical Modelling of Geophysical Flows. Atmosphere-Ocean. ISSN 0705-5900. 35, p. 557–581. Full text in Research Archive
• Alm, Leif Kristian & Nygaard, Tor Anders (1995). Flow over complex terrain estimated by a general-purpose Navier-Stokes Solver. MIC Journal: Modeling, Identification and Control. ISSN 0332-7353. 16(3), p. 169–176. Full text in Research Archive
• Nygaard, Tor Anders (1992). Estimating expected energy capture at potential wind turbine sites in Norway. Journal of Wind Engineering and Industrial Aerodynamics. ISSN 0167-6105. 39(1-3), p. 385–393. Full text in Research Archive

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• Mian, Haris Hameed; Siddiqui, Muhammad Salman; Franchina, Nicoletta; Kouaissah, Otman; Wang, Gang & Nygaard, Tor Anders (2024). Aerodynamic and Structural Assessment of FOWT Rotor Under Varying Tilt Angle. Full text in Research Archive Show summary

  The effect of wind and waves results in a sixdegree- of-freedom motion of the platform, directly influencing turbine performance. This research examines the effects of rotor tilt angle on both aerodynamic performance and structural response employing computational fluid dynamics (CFD) analysis and mapping aerodynamic loads onto the finite element (FE) mesh for structural analysis of NREL 5MW reference wind turbine rotor. Increased rotor tilt angle reduces turbine performance. Fluidstructure analysis shows higher flap-wise displacement with larger tilt angles, impacting thrust and power output. The displacement and stress patterns aligns with observed data.

• Sakaris, Christos; Schlanbusch, Rune; Nygaard, Tor Anders; Sakellariou, John & Tutkun, Murat (2023). Statistical times series based damage detection in the fiber rope mooring lines of the semi-submersible OO-STAR wind floater. Full text in Research Archive Show summary

  The Floating Offshore Wind Turbines (FOWTs) based on semi-submersible floaters constitute a popular choice in most markets due to their installation being flexible and in need of low infrastructural requirements. A simple and robust three-legged semi-submersible floater for FOWTs, the OOSTAR wind floater, has been introduced and it can be anchored to the seabed with steel chain mooring lines or hybrid mooring lines - a combination of chains and synthetic fiber ropes. The fiber rope mooring lines present a number of advantages thus leading to a lighter and less costly mooring system. These lines are important for the FOWT’s integrity as their loss can lead to the change of the floater’s position, a damaged power cable, a possible collision with other infrastructure and high maintenance costs. This why an early detection of damages in the mooring system is crucial. In this study, damage detection in the main part of fiber rope mooring lines of semi-submersible based FOWTs is investigated for the first time. In particular, the OO-STAR floater based FOWT is considered. Two Statistical Time Series based detection methods, the Multiple Model- AutoRegressive (MM-AR) method and the Functional Model Based Method (FMBM) are used and compared. The MM-AR is based on multiple AR models whereas the FMBM on a single Functional Model, for the description of the healthy FOWT’s dynamics under varying environmental conditions. The results based on seven healthy and eight damage cases under varying wind speed and wave height show that the two methods are able to achieve damage detection in fiber rope mooring lines without any false alarm or missed damage despite of damages having small effects on the FOWT’s dynamics and the fiber ropes presenting a non-linear behaviour.

• Nygaard, Tor Anders; Fromreide, Mads & Eide, Kurt (2022). Creep and dynamic stiffness properties of nylon ropes. Comparisons of test results and computations. Full text in Research Archive
• Nygaard, Tor Anders; Zhang, Bin; Andersen, Håkon; Nordgård-Hansen, Ellen Marie & Kaynia, Amir M. (2021). FibreRope Mooring for Floating Wind Turbines. Full text in Research Archive
• Oggiano, Luca; Arens, Emile; Myhr, Anders; Nygaard, Tor Anders & Evans, Steve (2015). CFD Simulations on a Tension Leg Buoy Platform for Offshore Wind Turbines and Comparison with Experiments. Full text in Research Archive
• Azcona, Jose; Bouchotrouch, Faisal; Gonzalez, M; Garciand, M; Munduate, Xavier & Kelberlau, Felix [Show all 7 contributors for this article] (2014). Aerodynamic Thrust Modelling in Wave Tank Tests of Offshore Floating Wind Turbines Using a Ducted Fan. Full text in Research Archive
• Robertson, Amy; Jonkman, Jason; Vorpahl, Fabian; Popko, Wojciech; Qvist, Jacob & Frøyd, Lars [Show all 38 contributors for this article] (2014). Offshore Code Comparison Collaboration Continuation Within IEA Wind Task 30: Phase II Results Regarding a Floating Semisubmersible Wind System. Full text in Research Archive
• Azcona, Jose; Munduate, Xavier; Hoyos, Merino & Nygaard, Tor Anders (2011). Development of OPASS code for dynamic simulation of mooring lines in contact with seabed. Full text in Research Archive
• Azcona, Jose; Munduate, Xavier; Hoyos, Merino & Nygaard, Tor Anders (2011). Dynamic simulation of mooring lines for floating wind turbines. Full text in Research Archive
• Maus, Karl Jacob & Nygaard, Tor Anders (2010). Flexible Wind Turbine Rotors Modelled with the Corotational Finite Element Method Wind energy: Aerodynamics and Structural Dynamics. Full text in Research Archive
• Nygaard, Tor Anders; Myhr, Anders & Maus, Karl Jacob (2010). Vil konkurrere ut Hywind. Full text in Research Archive Show summary

  Under ledelse av IFE-forsker og UMB-professor i maskinteknikk, Tor Anders Nygaard, jobber Anders Myhr og Karl Jacob Maus, en annen stipendiat og to masterstudenter med å utvikle en ny teknologi for flytende havvindturbiner. I løpet av fire år er det skrevet 14 masteroppgaver om offshore vindkraft ved UMB. Målet er å kutte kostnader der det er mulig og samtidig få en fullverdig turbinløsning

• Myhr, Anders; Moss, David Wauthier & Nygaard, Tor Anders (2009). Large Scale Assembly and Erection of Floating Offshore Wind Turbines. Full text in Research Archive Show summary

  The investigation has been carried out with a conceptual design of a semisubmersible platform operating on site in offshore locations. Analysis has been carried out with four different single buoy turbine concepts to verify loads occurring during challenging operating conditions set to 90% of the time within the North Sea region. Pivot rotation by the means of ballast transfer is a common technology used in the offshore industry. Utilizing the concept on floating wind turbines is yet to be explored and seems to have a large potential. Adequate measures must be taken in order to ensure that the pivot concept can handle the final geometries of the turbine towers. At this early stage it is not known what kind of floating turbine concept will be proven to be economically viable. Making the pivot concept adaptable to several different wind turbine concepts is thus important. One other main goal is to incorporate all of the assembly features from connecting the individual tower parts to handling the anchor lines for the wind turbines. Worst case loading conditions are dependent on dynamic response from the assembly platform. Current results with simulations of the complete system indicate that the pivot concept performs as anticipated. The versatility for application on different assembly platforms is yet to be proven but should result in less dynamic response and loading on both the pivot concept and turbine towers. It is clear that turbines with a smaller draught will make assembly more versatile and less sensitive to weather conditions.

• Nygaard, Tor Anders & Maus, Karl Jacob (2009). IEA Phase IV of OC3 Offshore Floating Wind Turbine Status March 2009 IEA Annex XXIII Offshore Code Comparison Collaborative (OC3) 10th Full Committee Meeting. Full text in Research Archive
• Maus, Karl Jacob & Nygaard, Tor Anders (2009). IEA Task 23 Offshore Code Comparison Collaborative (OC3) UMB Status September 2009 IEA Task 23 Offshore Code Comparison Collaborative (OC3) 11th Full Committee Meeting. Full text in Research Archive
• Nygaard, Tor Anders; Myhr, Anders & Maus, Karl Jacob (2009). A comparison of two concepts for floating wind turbines Technology and innovation track: New concepts in wind turbine and offshore technology. Full text in Research Archive
• Strawn, Roger; Nygaard, Tor Anders; Dimanlig, Arsenio; Saberi, Hossein & Ormiston, Robert (2007). Integrated Computational Fluid and Structural Dynamics Analyses for Comprehensive Rotorcraft Analysis. Full text in Research Archive
• Lim, Joon; Nygaard, Tor Anders; Strawn, Roger & Potsdam, Mark (2006). BVI Airloads Prediction Using Loose CSD/CFD Coupling. Full text in Research Archive
• Nygaard, Tor Anders; Saberi, Hossein; Ormiston, Robert; Strawn, Roger & Potsdam, Mark (2006). CFD and CSD Coupling Algorithms and Fluid Structure Interface for Rotorcraft Aeromechanics in Steady and Transient Flight Conditions. Full text in Research Archive
• Lim, Joon; Potsdam, Mark; Strawn, Roger; Sim, Ben & Nygaard, Tor Anders (2006). Blade-Vortex Interaction Prediction Using Multidisciplinary Coupling. Full text in Research Archive
• Hertel, Jonas N.; Nygaard, Tor Anders & Duque, Earl P. (2004). Passive Pitch Control Of Small Horizontal Axis Wind Turbines. Full text in Research Archive Show summary

  Finnes som IMT-trykk 11/2004

• Nygaard, Tor Anders; Dimanlig, Arsenio & Meadowcroft, E. T. (2004). Application of a Momentum Source Model to the RAH-66 Comanche FANTAIL. Full text in Research Archive
• Nygaard, Tor Anders (2003). Aeromechanic Analysis of A Missile with Freely Spinning Tailfins. Full text in Research Archive
• Nygaard, Tor Anders & Meakin, Robert L. (2002). An Aerodynamic Analysis of a Spinning Missile with Dithering Canards. Full text in Research Archive
• Nygaard, Tor Anders (2000). Status and Prospects for Windpower in Norway. Full text in Research Archive
• Nygaard, Tor Anders (1999). Three-Dimensional Euler Flow-Field Computations Through a Wind Turbine Rotor. Full text in Research Archive
• Santos, Carlos Renan dos; Mendoza, Alejandra S. Escalera; Abdelmoteleb, Serag-Eldin; Griffith, D. Todd; Bachynski-Polic, Erin Elizabeth & Oggiano, Luca [Show all 11 contributors for this article] (2025). Definition of the 25 MW IFE UPSCALE Offshore Reference Wind Turbine. Institutt for energiteknikk. ISSN 9788270179565. Full text in Research Archive Show summary

  This report provides a comprehensive overview of the 25 MW offshore wind turbine developed as part of the UPSCALE project (2020–2024). It details the key design features and performance characteristics of the rotor blades, tower, semisubmersible floating platform, and control system.

• Nygaard, Tor Anders (2013). Wave tank testing of Tension-Leg-Buoy (TLB) offshore wind power platforms. SINTEF Energi AS. Full text in Research Archive

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