FAST modularization framework for wind turbine simulation: full-system linearization

Jonkman, Jason; Jonkman, Bonnie

doi:10.1088/1742-6596/753/8/082010

Cited by 61 publications

(77 citation statements)

References 5 publications

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“…As for why MI10 seems to under-perform when compared to the others, this is likely Sample set size because the changes to the global eigenfrequency induced by scaling all elements by 10% can lead to dynamic amplification for lower wind speed load cases when the frequency increases (corresponding to the structure being scaled up). In this particular situation, there is a significant shift towards the 3P frequency of the turbine, as seen from the Campbell diagram of the NREL 5MW turbine (Jonkman and Jonkman, 2016). The result is a significant increase in the severity of lower wind speed load cases, which means that the error in including only the most severe load cases in the fatigue estimation changes more drastically for 5 this design.…”

Section: Uniformly Scaled Designsmentioning

confidence: 94%

Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures by a simple severity-based sampling method

Stieng¹,

Muskulus²

2018

Preprint

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Abstract. The large amount of computational effort required for a full fatigue assessment of offshore wind turbine support structures under operational conditions can make these analyses prohibitive. Especially for applications like design optimization, where the analysis would have to be repeated for each iteration of the process. To combat this issue, we present a simple procedure for reducing the number of load cases required for an accurate fatigue assessment. After training on one full fatigue analysis of a base design, the method can be applied to establish a deterministic, reduced sampling set to be used for a family 5 of related designs. The method is based on sorting the load cases by their severity, measured as the product of fatigue damage and probability of occurrence, and then calculating the relative error resulting from using only the most severe load cases to estimate the total fatigue damage. By assuming this error to be approximately constant, one can then estimate the fatigue damage of other designs using just these load cases. The method yields a maximum error of about 6% when using around 30 load cases (out of 3647) and, for most cases, errors of less than 1-2% can be expected for sample sizes in the range 15-60. One 10 of the main points in favor of the method is its simplicity when compared to more advanced sampling-based approaches. The method as is can be used without further modifications and is especially useful for design optimization and preliminary design.We end the paper by noting a few possibilities for future work that extend or improve upon the method.

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Section: Uniformly Scaled Designsmentioning

confidence: 94%

Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures by a simple severity-based sampling method

Stieng¹,

Muskulus²

2018

Preprint

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“…The turbine and support structure models used in this study are the NREL 5MW turbine and the OC3 monopile, respectively. The time domain analysis has been performed using the fully integrated aero‐elastic software FEDEM Windpower .…”

Section: Background and Methodologymentioning

confidence: 99%

Load case reduction for offshore wind turbine support structure fatigue assessment by importance sampling with two‐stage filtering

Stieng

Muskulus

2019

Wind Energy

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A complete fatigue assessment for operational conditions for offshore wind turbines involves simulating thousands of environmental states. For applications such as optimization, where this assessment needs to be repeated many times, that presents a significant computational problem. Here, we propose a novel way of reducing the number of simulated environmental states (load cases) while maintaining an acceptable accuracy. From one full fatigue analysis of a base design, the OC3 monopile (with the NREL 5MW turbine), the distribution of fatigue damage per load case can be used to estimate the lifetime fatigue damage of a range of modified designs. Using importance sampling and a specially adapted two‐stage filtering procedure, we obtain pseudo‐optimal sets of load cases from which the fatigue damage is estimated. This is applied to seven different designs that have been modified to emulate iterations of an optimization loop. For several of these designs, sampling less than 1% of all load cases can give damage estimates with median errors of less than 2%. Even for the most severe cases, using 3% of the environmental states yields a maximum error of 10%. While further refinement is possible, the method is considered viable for applications within design optimization and preliminary design.

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“…To validate the FE model utilized, a reliable modal test result for a single blade with the same structural configuration is required; to the authors' knowledge, there is no reliable modal analysis result for a single blade of the NREL 5MW baseline wind turbine. In relation to NREL 5MW wind turbine modal parameters, the available data from [15,23,26,27] can be considered. However, most of the available data for modal parameters of the NREL 5MW turbine are the results of a full-system analysis, including the blades, drivetrain, nacelle, and tower.…”

Section: Fe Modelmentioning

confidence: 99%

“…Assessing Figure 8 and the modal frequencies for each mode, the frequencies of the FE model and LMH64-5 blade are closer for the 1st, 2nd and 4th mode but a significant difference is seen in the third mode, i.e., the 2nd flapwise mode. Another justification for the FE model can be drawn from the Campbell diagram of the blade given at Figure 9; the trend of the modal frequency with the rotor speed can be fairly considered to be similar to the reference blade [26]. Another justification for the FE model can be drawn from the Campbell diagram of the blade given at Figure 9; the trend of the modal frequency with the rotor speed can be fairly considered to be similar to the reference blade [26].…”

Section: Fe Modelmentioning

confidence: 99%

“…Another justification for the FE model can be drawn from the Campbell diagram of the blade given at Figure 9; the trend of the modal frequency with the rotor speed can be fairly considered to be similar to the reference blade [26]. Another justification for the FE model can be drawn from the Campbell diagram of the blade given at Figure 9; the trend of the modal frequency with the rotor speed can be fairly considered to be similar to the reference blade [26]. Evaluating the above justifications and comparing the FSI results with the theoretical backgrounds, both the CFD and FE model of the wind turbine blade employed in this article can be fairly considered valid to compare the two FSI (uni-directional and bi-directional) models.…”

Section: Fe Modelmentioning

confidence: 99%

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Comparative Study on Uni- and Bi-Directional Fluid Structure Coupling of Wind Turbine Blades

Ageze

2017

Energies

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Abstract:The current trends of wind turbine blade designs are geared towards a longer and slender blade with high flexibility, exhibiting complex aeroelastic loadings and instability issues, including flutter; in this regard, fluid-structure interaction (FSI) plays a significant role. The present article will conduct a comparative study between uni-directional and bi-directional fluid-structural coupling models for a horizontal axis wind turbine. A full-scale, geometric copy of the NREL 5MW blade with simplified material distribution is considered for simulation. Analytical formulations of the governing relations with appropriate approximation are highlighted, including turbulence model, i.e., Shear Stress Transport (SST) k-ω. These analytical relations are implemented using Multiphysics package ANSYS employing Fluent module (Computational Fluid Dynamics (CFD)-based solver) for the fluid domain and Transient Structural module (Finite Element Analysis-based solver) for the structural domain. ANSYS system coupling module also is configured to model the two fluid-structure coupling methods. The rated operational condition of the blade for a full cycle rotation is considered as a comparison domain. In the bi-directional coupling model, the structural deformation alters the angle of attack from the designed values, and by extension the flow pattern along the blade span; furthermore, the tip deflection keeps fluctuating whilst it tends to stabilize in the uni-directional coupling model.

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FAST modularization framework for wind turbine simulation: full-system linearization

Cited by 61 publications

References 5 publications

Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures by a simple severity-based sampling method

Reducing the number of load cases for fatigue damage assessment of offshore wind turbine support structures by a simple severity-based sampling method

Load case reduction for offshore wind turbine support structure fatigue assessment by importance sampling with two‐stage filtering

Comparative Study on Uni- and Bi-Directional Fluid Structure Coupling of Wind Turbine Blades

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