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218 results on '"Branlard, Emmanuel"'

5. The nonlinear behavior of generic tail fins for small wind turbines.

Author

Khedr, Amr A., Hammam, Mohamed M., Gupta, Abhineet, Branlard, Emmanuel, Castellani, Francesco, and Wood, David H.

Subjects
BEHAVIORAL assessment, WIND measurement, WIND tunnels, WIND turbines, NONLINEAR theories
Abstract

This paper describes analysis and measurements of the yaw response of tail fins for small wind turbines. It is based on an extension of unsteady slender body theory (USBT) to cover non-slender fins and high angles of incidence, both of which make the theory nonlinear. We provide three main additions to the substantial literature on linearized USBT for tail fins. First, USBT is extended to high angles by modeling the nonlinear vortex dynamics. Second, the restriction to slender bodies is removed by modeling the chordwise load variation. Third, we consider the effect of time-varying wind speed. The extended theory is compared to wind tunnel measurements of the yaw behavior of delta, elliptical, and rectangular tail fins without a rotor and nacelle. The fins were released from initial yaw angles of −40° and −80°; the latter is of sufficient magnitude to show the importance of the nonlinear yaw dynamics. Generally good agreement was found between the theory and measurements, and the theory was shown to be more accurate than a "polar" or quasi-steady model which uses only the lift and drag of a delta planform. Of the three planforms, the rectangular one showed the lowest accuracy in terms of frequency but the damping was accurately predicted. Overall, the results demonstrate the importance of nonlinearity in the response of a yawing tail fin, particularly for the higher aspect ratio fins at large yaw angles. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Wind Turbine Aeroelastic Stability in OpenFAST

Author

Bortolotti, Pietro, Chetan, Mayank, Branlard, Emmanuel, Jonkman, Jason, Platt, Andy, Slaughter, Derek, Rinker, Jennifer, Bortolotti, Pietro, Chetan, Mayank, Branlard, Emmanuel, Jonkman, Jason, Platt, Andy, Slaughter, Derek, and Rinker, Jennifer

Abstract

Wind turbines are growing in size and increasingly suffer from aeroelastic instabilities. Unfortunately, numerical models often show inconsistent results during verification studies. We address this gap by first introducing novel linearization capabilities within the open-source aero-hydro-servo-elastic framework OpenFAST. Next, a code-to-code benchmark study is presented that compares modal parameters between OpenFAST and HAWCStab2 for a land-based version of the International Energy Agency 15-MW reference wind turbine modeled with quasi-steady aerodynamics. The two solvers are in strong agreement except for discrepancies in the second rotor flapwise modes. The differences are attributed to the torsional flexibility of the tower, which is assumed torsionally stiff in the OpenFAST model. Work is ongoing to close this modeling gap. The aeroelastic stability of a low-specific-power land-based wind turbine is also investigated. The impact of design choices is discussed, high-lighting how narrow the margins are between a stable design and an unstable design.

Published
2024

7. One-to-one aeroservoelastic validation of operational loads and performance of a 2.8 MW wind turbine model in OpenFAST.

Author

Brown, Kenneth, Bortolotti, Pietro, Branlard, Emmanuel, Chetan, Mayank, Dana, Scott, deVelder, Nathaniel, Doubrawa, Paula, Hamilton, Nicholas, Ivanov, Hristo, Jonkman, Jason, Kelley, Christopher, and Zalkind, Daniel

Subjects
AEROSERVOELASTICITY, WIND turbines, KINEMATICS, AERODYNAMICS, DEFORMATIONS (Mechanics)
Abstract

This article presents a validation study of the popular aeroservoelastic code suite OpenFAST leveraging weeks of measurements obtained during normal operation of a 2.8 MW land-based wind turbine. Measured wind conditions were used to generate one-to-one turbulent flow fields (i.e., comparing simulation to measurement in 10 min increments, or bins) through unconstrained and constrained assimilation methods using the kinematic turbulence generators TurbSim and PyConTurb. A total of 253 bins of 10 min of normal turbine operation were selected for analysis, and a statistical comparison in terms of performance and loads is presented. We show that successful validation of the model was not strongly dependent on the type of inflow assimilation method used for mean quantities of interest, which had median modeling errors per wind-speed interval generally within 5 %–10 % of the measurement. The type of inflow assimilation method did have a larger effect on the fatigue predictions for blade-root flapwise and tower-base fore–aft quantities, which surprisingly saw larger errors from the assumed higher-fidelity assimilation methods. Avenues for further work are discussed and include possible improvements to the aerodynamic, structural, and controller modeling that may offer insight on the origin of the up to ∼ 40 % median overprediction of fatigue for these quantities. [ABSTRACT FROM AUTHOR]

Published
2024
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8. One-to-one aeroservoelastic validation of operational loads and performance of a 2.8 MW wind turbine model in OpenFAST

Author

Brown, Kenneth, primary, Bortolotti, Pietro, additional, Branlard, Emmanuel, additional, Chetan, Mayank, additional, Dana, Scott, additional, deVelder, Nathaniel, additional, Doubrawa, Paula, additional, Hamilton, Nicholas, additional, Ivanov, Chris, additional, Jonkman, Jason, additional, Kelley, Christopher, additional, and Zalkind, Daniel, additional

Published
2024
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45. Momentum Theory

Author

Branlard, Emmanuel, Peinke, Joachim, Series editor, von Bussel, Gerard, Series editor, and Branlard, Emmanuel

Published
2017
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