User's Guide to BModes (Software for Computing Rotating Beam-Coupled Modes)

Bir, Gunjit

doi:10.2172/861489

Cited by 52 publications

(47 citation statements)

References 3 publications

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“…Next, we perform eigenanalysis to obtain frequencies and mode shapes. We use BModes [2] for modeling a specific turbine configuration and for computing its modes. A brief description of BModes follows.…”

Section: Modal Analysis Approachmentioning

confidence: 99%

“…We had developed a finite-element code, called BModes (Beam Modal Analysis Code) [2], to determine high-fidelity modes of turbine blades, rotating or non-rotating, and landbased towers. Realizing the emerging interest in offshore turbines, we recently extended the code to also handle towers supported either on floating platforms or on monopile foundations.…”

Section: Introductionmentioning

confidence: 99%

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Modal Dynamics of Large Wind Turbines With Different Support Structures

Bir

Jonkman

2008

Volume 6: Nick Newman Symposium on Marine Hydrodynamics; Yoshida and Maeda Special Symposium on Ocean Space Utilization; Specia

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This paper presents modal dynamics of floating-platformsupported and monopile-supported offshore turbines, which are gaining attention for their ability to capture the immense wind resources available over coastal waters. Minimal dynamic loads and the absence of instability are imperative to the success of these turbines. Modal dynamics determine both loads and instabilities to a large extent, and therefore must always be analyzed. Also, to model the turbine, several aeroelastic computer codes require modes of the major components, e.g., the rotor blades and the rotor-nacelle support structure. To compute such modes, we used a recently developed finiteelement code called BModes. The code provides coupled modes either for the rotating blades or for the support structure. A coupled mode implies presence of coupled flexural, axial, and torsion motions in a natural mode of vibration. In this paper, we use BModes to provide modes only for flexible towers, which carry head mass (rotor-nacelle subassembly modeled as a rigid body) and are mounted atop either a floating platform or a soilsupported monopile. The code accounts for the effects of hydrodynamic inertia, hydrostatic restoring, and mooring lines stiffness on the floating platform. It also accounts for the distributed hydrodynamic mass on the submerged part of the tower and for the elastic foundation surrounding the monopile. Results are obtained for three turbine configurations: land-based turbine, floating-platform-supported turbine, and monopilesupported turbine. Three foundation models are used for the monopile configuration. Results show that the hydrodynamic and elastic-foundation effects strongly influence the turbine modal dynamics.

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Section: Modal Analysis Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modal Dynamics of Large Wind Turbines With Different Support Structures

Bir

Jonkman

2008

Volume 6: Nick Newman Symposium on Marine Hydrodynamics; Yoshida and Maeda Special Symposium on Ocean Space Utilization; Specia

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show abstract

“…Since the tower mode shapes are strongly affected by the tower-base boundary conditions especially as mounted on a floating platform, the finite-element-method (FEM) based software BModes [50] capable of handling the coupled modal issues with complex boundary conditions was adopted in this study. The parameters that related to the tower vibration mode shapes such as the tower mass and stiffness distribution, tower-top mass, floating platform mass, added mass, hydrostaric stiffness and mooring stiffness were served as input to BModes, then the inertial and stiffness matrices of the whole system were constructed.…”

Section: Structural Modeling Of the Towermentioning

confidence: 99%

Directionality Effects of Aligned Wind and Wave Loads on a Y-Shape Semi-Submersible Floating Wind Turbine under Rated Operational Conditions

et al. 2017

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Abstract:The Y-shape (triangular) semi-submersible foundation has been adopted by most of the built full-scale floating wind turbines, such as Windfloat, Fukushima Mirai and Shimpuu. Considering the non-fully-symmetrical shape and met-ocean condition, the foundation laying angle relative to wind/wave directions will not only influence the downtime and power efficiency of the floating turbine, but also the strength and fatigue safety of the whole structure. However, the dynamic responses induced by various aligned wind and wave load directions have scarcely been investigated comparatively before. In our study, the directionality effects are investigated by means of combined wind and wave tests and coupled multi-body simulations. By comparing the measured data in three load directions, it is found that the differences of platform motions are mainly derived from the wave loads and larger pitch motion can always be observed in one of the directions. To make certain the mechanism underlying the observed phenomena, a coupled multi-body dynamic model of the floating wind turbine is established and validated. The numerical results demonstrate that the second-order hydrodynamic forces contribute greatly to the directionality distinctions for surge and pitch, and the first-order hydrodynamic forces determine the variations of tower base bending moments and nacelle accelerations. These findings indicate the directionality effects should be predetermined comprehensively before installation at sea, which is important for the operation and maintenance of the Y-shape floating wind turbines.

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“…PreComp outputs blade section properties in tabular form, which may be readily exported to a plotting utility such as a spreadsheet application, to a beam analysis code such as BModes [9], or to an aeroelastic code such as FAST. In fact, the main motivation for PreComp development is to eventually integrate it with FAST to handle composite rotor blades.…”

Section: Output Descriptionmentioning

confidence: 99%

“…These parameters represent all properties computed by PreComp and refer to axes systems shown in Figure 13. The BModes-compatible output file shows only select section properties that are compatible with the BModes code and refers to axes systems explained in the BModes User's Guide [9]. …”

Section: Output Descriptionmentioning

confidence: 99%

User's Guide to PreComp (Pre-Processor for Computing Composite Blade Properties)

Bir¹

2006

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User's Guide to BModes (Software for Computing Rotating Beam-Coupled Modes)

Cited by 52 publications

References 3 publications

Modal Dynamics of Large Wind Turbines With Different Support Structures

Modal Dynamics of Large Wind Turbines With Different Support Structures

Directionality Effects of Aligned Wind and Wave Loads on a Y-Shape Semi-Submersible Floating Wind Turbine under Rated Operational Conditions

User's Guide to PreComp (Pre-Processor for Computing Composite Blade Properties)

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