The effects of blade structural model fidelity on wind turbine load analysis and computation time

Gözcü, Ozan; Verelst, David Robert

doi:10.5194/wes-5-503-2020

Cited by 20 publications

(12 citation statements)

References 22 publications

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“…MIRAS‐LL simulations employ a bound vortex discretized with 40 straight segments following a cosinus distribution, where the root and the tip region have a higher point density. The influence of the HAWC2 structural model fidelity of the blade on the response, loads, and stability of large turbines has been analyzed in Gözcü and Verelst 46 . A 28R × 4R × 4R Cartesian mesh has been employed in all cases, with a constant spacing of 3 m in the x , y , and z directions which adds up to a total of approximately 29 million cells.…”

Section: Choice Of Simulation Casesmentioning

confidence: 99%

“…The influence of the HAWC2 structural model fidelity of the blade on the response, loads, and stability of large turbines has been analyzed in Gözcü and Verelst. 46 A 28R Â 4R Â 4R Cartesian mesh has been employed in all cases, with a constant spacing of 3 m in the x, y, and z directions which adds up to a total of approximately 29 million cells. This cell size has been chosen to be equal to the one used to resolve the wake behind the complex multi-rotor turbine in van der Laan.…”

Section: Computational Setupmentioning

confidence: 99%

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Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

et al. 2021

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Floating wind turbines have the potential to enable global exploitation of offshore wind energy, but there is a need to further understand the complex aerodynamic phenomena they can encounter due to floater induced rotor motion. Aerodynamic models traditionally used in the wind energy sector, like the Blade Element Momentum (BEM) theory, may not be capable of capturing the dynamic phenomena that occur when the rotor moves in and out of its own wake. In the present paper, we therefore compare an industry standard BEM‐based code to a state of the art vortex solver, to investigate the phenomena in detail and further clarify the capabilities and limitations of both methods. An initial benchmark of the two codes using the IEA Wind 15 MW RWT mounted on the WindCrete spar‐buoy floater is carried out. Three different scenarios are taken into account: a bottom‐fixed, a floating case, and a floating case subject to regular waves. Growing discrepancies between the codes have been observed with the increasing complexity of the simulations. Moreover, large differences between the wake generated by a bottom fixed and a floating turbine have been observed, with the latter one experiencing a faster recovery. To further explore the floating turbines behaviors that can affect the rotor performance and wake, a systematic investigation of the mean tilt angle influence in the wake development has been carried out. Further, to account for the oscillatory motion of a floating turbine, a parametric study where the floater motion is prescribed in both pitch and surge degrees of freedom (DoF) is designed. The study covers a large variety of scenarios; a wide range of relevant frequencies and amplitudes are taken into account in under and above‐rated wind conditions. A total of more than 28 unique cases have been defined and simulated with both fidelity models. The results include the downstream evolution of the wake recovery and intensity of the turbulent disturbances induced by the rotor. The generic nature of the study allows to characterize the flow and performance effects and enables subsequent generalization to floater designs of given natural frequency and motion amplitude. It has been found that the BEM and LL predictions of the maximum loading in the blade root and tower bottom compare quite well, except for the case of large oscillation frequency in above rated conditions, where the BEM method under‐predicts the loads. Moreover, the use of a vortex solver makes it possible to look in depth into the wake characteristics, in which large differences are observed between the bottom‐fixed and the floating case in non‐turbulent inflow conditions. It has been found that the frequency and amplitude of the turbine oscillations can have a strong impact on the recovery of the wake. Moreover, we have found a link between short time intervals of large FA blade tip displacements and a faster break down of the wake. Finally it has been shown that a floating wind turbine with large and fast oscillations can transition between the differ...

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Section: Choice Of Simulation Casesmentioning

confidence: 99%

Section: Computational Setupmentioning

confidence: 99%

Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

et al. 2021

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“…The MIRAS‐LL simulations employ a bound vortex discretized with 40 straight segments following a cosine distribution, where the root and the tip region have a higher point density. The influence of the HAWC2 structural model fidelity of the blade on the response, loads, and stability of large turbines has been analyzed in Gözcü and Verelst 41 . The turbine hub is located at a position of 1.125R from the water level, and its wake effect has not been included in the present modeling approach.…”

Section: Numerical Models and Computational Setupmentioning

confidence: 99%

“…The influence of the HAWC2 structural model fidelity of the blade on the response, loads, and stability of large turbines has been analyzed in Gözcü and Verelst. 41 The turbine hub is located at a position of 1.125R from the water level, and its wake effect has not been included in the present modeling approach. An eight-order stencil is used to spatially discretize the vorticity equation.…”

Section: Computational Setupmentioning

confidence: 99%

Investigation of the floating IEA wind 15‐MW RWT using vortex methods Part II: Wake impact on downstream turbines under turbulent inflow

et al. 2022

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The manuscript presents a novel numerical investigation on the impact of the wake of a floating IEA wind 15-MW reference wind turbine (RWT) on downstream machines using a state-of-the-art vortex solver coupled to a multi-body code. The coupling enables to account for the flexibility of the different turbine components as well as to include the effect of the controller and the dynamics of the floating support structure. First, the turbine is mounted on the WindCrete spar-buoy platform, and the wake impact on a second turbine positioned at different downstream positions is investigated and compared with the impact of the wake generated by a bottom-fixed machine. It is found that the faster breakdown of the vortex structures triggered by the motion of the floater in the upstream turbine increases the power

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“…The blades are constrained around the hub node with revolute constraints, allowing for rotations around the pitch axis. HAWC2 makes use of a multi-body floating reference framework with Timoshenko beam elements instead, allowing for the capability to account for structural shear forces [32]. The turbine is modeled with nine bodies, one for each blade and corresponding hub, one for the tower and tower top and ultimately one for the shaft.…”

Section: Aeroelastic Couplingmentioning

confidence: 99%

Comparison of different fidelity aerodynamic solvers on the IEA 10 MW turbine including novel tip extension geometries

Luna

Marten

Barlas

et al. 2022

J. Phys.: Conf. Ser.

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Lifting-line based solvers could supersede the blade element momentum (BEM) method as the industry standard in the near future as rotor sizes of modern wind turbines and computational resources continue to increase. A comparison study between both methods is presented where the IEA 10 MW wind turbine is evaluated in the aero-servo-elastic simulation tool QBlade, comparing the lifting-line free vortex wake method to an unsteady blade element momentum solver. Besides the baseline rotor of the IEA 10 MW turbine, the comparison includes several blade tip extensions, including a swept and a dihedral geometry, to further differentiate capabilities between both methods in aerodynamically complex flow fields. As a reference serve results from equivalent simulations performed with multiple fidelity solvers of the simulation tool HAWC2. Results of a rigid load case demonstrate considerable improvement regarding the aerodynamic accuracy of lifting-line based methods in below rated conditions over BEM codes. The aerodynamic loads on geometrically complex tip extensions in steady conditions prove good capabilities of lower fidelity codes to predict out-of-plane bend shapes but also clear limitations regarding loads on swept geometries. A quasi-steady aeroelastic load case further demonstrates the capability of both QBlade codes to produce comparable results to similar fidelity solvers of the HAWC2 tool on an integral level. A detailed comparison in the time domain shows a larger dependency of the results on the type of structural solver that is used in contrast to the fidelity level of the aerodynamic method.

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The effects of blade structural model fidelity on wind turbine load analysis and computation time

Cited by 20 publications

References 22 publications

Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

Investigation of the floating IEA wind 15‐MW RWT using vortex methods Part II: Wake impact on downstream turbines under turbulent inflow

Comparison of different fidelity aerodynamic solvers on the IEA 10 MW turbine including novel tip extension geometries

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