Summary of the Blind Test Campaign to predict the High Reynolds number performance of DU00-W-210 airfoil

Yilmaz, Özlem Ceyhan; Pires, Oscar; Munduate, Xabier; Sørensen, Niels N.; Reichstein, Torben; Schaffarczyk, P.; Diakakis, Konstantinos; Papadakis, G.; Daniele, Elia; Schwarz, Michael; Lutz, Thorsten; Prieto, Raul

doi:10.2514/6.2017-0915

Cited by 16 publications

(24 citation statements)

References 13 publications

(24 reference statements)

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“…EllipSys3D was found to be 2-6 times faster while producing almost identical numerical results (Cavar et al, 2016). More recent sources also show that these two solvers yield comparable results (Sørensen et al, 2016;Yilmaz et al, 2017;Boorsma et al, 2018).…”

Section: Ellipsys3dmentioning

confidence: 76%

“…To optimize with respect to large numbers of variables, gradient-based algorithms are the only hope if one wishes to achieve convergence to an optimum in a reasonable amount of time (Yu et al, 2018). The efficiency of gradient-based optimization is dependent in large part on the cost and accuracy of computing the gradients.…”

Section: Low-fidelity and Multi-fidelity Shape Optimizationmentioning

confidence: 99%

“…The volume deformation tool is called IDWarp and is based on the inverse distance weighting function (Edward et al, 2012). IDWarp is a fast and unstructured deformation algorithm that has been demonstrated in aerodynamic (Yu et al, 2018;He et al, 2018) and aerostructural applications (Brooks et al, 2018).…”

Section: Geometry and Mesh Deformationmentioning

confidence: 99%

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Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Madsen¹,

Zahle²,

Sørensen³

et al. 2019

Wind Energ. Sci.

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Abstract. The wind energy industry relies heavily on computational fluid dynamics (CFD) to analyze new turbine designs. To utilize CFD earlier in the design process, where lower-fidelity methods such as blade element momentum (BEM) are more common, requires the development of new tools. Tools that utilize numerical optimization are particularly valuable because they reduce the reliance on design by trial and error. We present the first comprehensive 3-D CFD adjoint-based shape optimization of a modern 10 MW offshore wind turbine. The optimization problem is aligned with a case study from International Energy Agency (IEA) Wind Task 37, making it possible to compare our findings with the BEM results from this case study and therefore allowing us to determine the value of design optimization based on high-fidelity models. The comparison shows that the overall design trends suggested by the two models do agree, and that it is particularly valuable to consult the high-fidelity model in areas such as root and tip where BEM is inaccurate. In addition, we compare two different CFD solvers to quantify the effect of modeling compressibility and to estimate the accuracy of the chosen grid resolution and order of convergence of the solver. Meshes up to 14×106 cells are used in the optimization whereby flow details are resolved. The present work shows that it is now possible to successfully optimize modern wind turbines aerodynamically under normal operating conditions using Reynolds-averaged Navier–Stokes (RANS) models. The key benefit of a 3-D RANS approach is that it is possible to optimize the blade planform and cross-sectional shape simultaneously, thus tailoring the shape to the actual 3-D flow over the rotor. This work does not address evaluation of extreme loads used for structural sizing, where BEM-based methods have proven very accurate, and therefore will likely remain the method of choice.

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Section: Ellipsys3dmentioning

confidence: 76%

Section: Low-fidelity and Multi-fidelity Shape Optimizationmentioning

confidence: 99%

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Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Madsen¹,

Zahle²,

Sørensen³

et al. 2019

Wind Energ. Sci.

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“…While the inflow turbulence intensity for an airplane wing in cruise is lower than the one experienced in a wind tunnel, it is higher for a rotating machinery or wind turbine rotors (Hernandez et al, 2012). Transition analysis performed for wind tunnel experiments in controlled conditions includes measurements on wind turbine airfoils equipped with pressure taps and sensors, balance system and a wake rake (Ceyhan et al, 2017); infrared thermography (Joseph et al, 2016); rotating turbine blade equipped with pressure sensors, strain gauges, balance system and particle image velocimetry (Schepers and Snel, 2007), rotating wind turbine and wind turbine blade experiments by oil visualization, stethoscope and flush-mounted unsteady pressure sensors (Lobo et al, 2018), wind turbine airfoil with pressure sensors and high frequency microphones (Özçakmak et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Özçakmak¹,

Madsen²,

Sørensen³

et al. 2020

Preprint

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Abstract. Laminar-turbulent transition behaviour of a wind turbine blade section is investigated in this study by means of field experiments and 3-D computational fluid dynamics (CFD) rotor simulations. The power spectral density (PSD) integrals of the pressure fluctuations obtained from the high frequency microphones mounted on a blade section are analyzed to detect laminar-turbulent transition locations from the experiments. The atmospheric boundary layer (ABL) velocities and the turbulence intensities (T.I.) measured from the field experiments are used to create several inflow scenarios for the CFD simulations. Results from the natural and the bypass transition models of the in-house CFD EllipSys code are compared with the experiments. It is seen that the bypass transition model results fit well with experiments at the azimuthal positions where the turbine is under wake and high turbulence, while the results from other cases show agreement with the natural transition model. Furthermore, the influence of inflow turbulence, wake of an upstream turbine and angle of attack (AOA) on the transition behaviour is investigated through the field experiments. On the pressure side of the blade section, at high AOA values and wake conditions, variation of the transition location covers up to 44 % of the chord during one revolution, while for the no wake cases and lower AOA values, variation occurs along a region that covers only 5 % of the chord. The effect of the inflow turbulence on the effective angle of attack as well as its direct effect on transition is observed. Transition locations for the wind tunnel conditions and field experiments are compared together with 2D and 3D CFD simulations. In contrast to the suction side, significant difference in the transition locations is observed between wind tunnel and field experiments on the pressure side for the same airfoil geometry. It is seen that the natural and bypass transition models of EllipSys3D can be used for transition prediction of a wind turbine blade section for high Reynolds number flows by applying various inflow scenarios separately to cover the whole range of atmospheric occurrences.

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“…Usually, a newly designed airfoil has to be tested in a wind tunnel. See [4] for an impressive example of high Reynolds number wind-tunnel testing, and a comparison with computational fluid dynamics (CFD). Panel codes like Xfoil, as well as genuine CFD codes like DLR-TAU [5], were used.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Laminar–Turbulent Transition on a Rotating Wind-Turbine Blade of Multimegawatt Class with Thermography and Microphone Array

et al. 2019

Self Cite

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Knowledge about laminar–turbulent transition on operating multi megawatt wind turbine (WT) blades needs sophisticated equipment like hot films or microphone arrays. Contrarily, thermographic pictures can easily be taken from the ground, and temperature differences indicate different states of the boundary layer. Accuracy, however, is still an open question, so that an aerodynamic glove, known from experimental research on airplanes, was used to classify the boundary-layer state of a 2 megawatt WT blade operating in the northern part of Schleswig-Holstein, Germany. State-of-the-art equipment for measuring static surface pressure was used for monitoring lift distribution. To distinguish the laminar and turbulent parts of the boundary layer (suction side only), 48 microphones were applied together with ground-based thermographic cameras from two teams. Additionally, an optical camera mounted on the hub was used to survey vibrations. During start-up (SU) (from 0 to 9 rpm), extended but irregularly shaped regions of a laminar-boundary layer were observed that had the same extension measured both with microphones and thermography. When an approximately constant rotor rotation (9 rpm corresponding to approximately 6 m/s wind speed) was achieved, flow transition was visible at the expected position of 40% chord length on the rotor blade, which was fouled with dense turbulent wedges, and an almost complete turbulent state on the glove was detected. In all observations, quantitative determination of flow-transition positions from thermography and microphones agreed well within their accuracy of less than 1%.

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Summary of the Blind Test Campaign to predict the High Reynolds number performance of DU00-W-210 airfoil

Cited by 16 publications

References 13 publications

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Investigation of Laminar–Turbulent Transition on a Rotating Wind-Turbine Blade of Multimegawatt Class with Thermography and Microphone Array

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