The Experts below are selected from a list of 123312 Experts worldwide ranked by ideXlab platform
Ernesto Benini - One of the best experts on this subject based on the ideXlab platform.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Abstract Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design. Evolutionary algorithms are thereby utilized to provide optimal configurations for different design objectives. The pure performance and the annual energy production are here considered in order to show the capabilities of the numerical code. A relevant increase in performance is achieved for all the obtained results, showing that the numerical optimization can be successfully adopted in vertical-axis wind turbine design procedures.
Gabriele Bedon - One of the best experts on this subject based on the ideXlab platform.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Abstract Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design. Evolutionary algorithms are thereby utilized to provide optimal configurations for different design objectives. The pure performance and the annual energy production are here considered in order to show the capabilities of the numerical code. A relevant increase in performance is achieved for all the obtained results, showing that the numerical optimization can be successfully adopted in vertical-axis wind turbine design procedures.
M Kibler - One of the best experts on this subject based on the ideXlab platform.
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an angular Momentum approach to quadratic fourier transform hadamard matrices gauss sums mutually unbiased bases the unitary group and the pauli group
Journal of Physics A, 2009Co-Authors: M KiblerAbstract:The construction of unitary operator bases in a finite-dimensional Hilbert space is reviewed through a nonstandard approach combining angular Momentum Theory and representation Theory of SU(2). A single formula for the bases is obtained from a polar decomposition of SU(2) and is analyzed in terms of cyclic groups, quadratic Fourier transforms, Hadamard matrices and generalized Gauss sums. Weyl pairs, generalized Pauli operators and their application to the unitary group and the Pauli group naturally arise in this approach.
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An angular Momentum approach to quadratic Fourier transform, Hadamard matrices, Gauss sums, mutually unbiased bases, unitary group and Pauli group
Journal of Physics A: Mathematical and Theoretical, 2009Co-Authors: M KiblerAbstract:The construction of unitary operator bases in a finite-dimensional Hilbert space is reviewed through a nonstandard approach combinining angular Momentum Theory and representation Theory of SU(2). A single formula for the bases is obtained from a polar decomposition of SU(2) and analysed in terms of cyclic groups, quadratic Fourier transforms, Hadamard matrices and generalized Gauss sums. Weyl pairs, generalized Pauli operators and their application to the unitary group and the Pauli group naturally arise in this approach.
Marco Raciti Castelli - One of the best experts on this subject based on the ideXlab platform.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design.
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optimization of a darrieus vertical axis wind turbine using blade element Momentum Theory and evolutionary algorithm
Renewable Energy, 2013Co-Authors: Gabriele Bedon, Marco Raciti Castelli, Ernesto BeniniAbstract:Abstract Wind turbine design procedures usually involve the adoption of the blade element – Momentum Theory. Nevertheless, its use is limited by the lack of extended database regarding the aerodynamic coefficients for most used airfoils. In the present work, an extended database generation procedure for symmetric profiles is discussed and validated with the aim of adopting numerical optimization methods for vertical-axis wind turbine design. Evolutionary algorithms are thereby utilized to provide optimal configurations for different design objectives. The pure performance and the annual energy production are here considered in order to show the capabilities of the numerical code. A relevant increase in performance is achieved for all the obtained results, showing that the numerical optimization can be successfully adopted in vertical-axis wind turbine design procedures.
Jens Nørkær Sørensen - One of the best experts on this subject based on the ideXlab platform.
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blade element Momentum Theory
2016Co-Authors: Jens Nørkær SørensenAbstract:Although there exists a large variety of methods for predicting performance and loadings of wind turbines, the only approach used today by wind turbine manufacturers is based on the blade-element/Momentum (BEM) Theory by Glauert (Aerodynamic Theory. Springer, Berlin, pp. 169–360, 1935). A basic assumption in the BEM Theory is that the flow takes place in independent stream tubes and that the loading is determined from two-dimensional sectional airfoil characteristics.
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general Momentum Theory for horizontal axis wind turbines
2015Co-Authors: Jens Nørkær SørensenAbstract:Introduction.- Basic Definitions.- One-dimensional Axial Momentum Theory.- The General Momentum Theory.- Optimum Rotor Performance Based on Momentum Theory.- Detailed Analysis of the Joukowsky Model.- Blade-Element/Momentum Theory.- The Tip Correction.- The Finite-bladed Betz Rotor.
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General Momentum Theory for wind turbines at low tip speed ratios
Wind Energy, 2010Co-Authors: Jens Nørkær Sørensen, Gijs Van KuikAbstract:General Momentum Theory is used to study the behaviour of the ‘classical’ free vortex wake model of Joukowsky. This model has recently attained considerable attention as it shows the possibility of achieving a power performance that greatly exceeds the Lanchester-Betz limit for rotors running at low tip speed ratios. This behaviour is confirmed even when including the effect of a centre vortex, allowing azimuthal velocities and the associated radial pressure gradient to be taken into account in the axial Momentum balance without any simplifying assumptions. It is shown that the most likely explanation for the anomalous behaviour at small tip speed ratios is that the influence of the lateral component of pressure and friction is neglected in the axial Momentum theorem. A refined model is proposed that remedies the problem of using the axial Momentum theorem and by which the power coefficient never exceeds the Lanchester-Betz limit and which tends to zero at zero tip speed ratio. Copyright © 2010 John Wiley & Sons, Ltd.
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analysis of wake states by a full field actuator disc model
Wind Energy, 1998Co-Authors: Jens Nørkær Sørensen, Wen Zhong Shen, X. MunduateAbstract:Various wake status have been analysed by a numerical method that combines the actuator disc principle with the Navier–Stokes equations. Results are compared with one-dimensional Momentum Theory and experiments. The computations are in excellent agreement with one-dimensional Momentum Theory for rotors working in the windmill brake state as well as in the propeller and hover states. The computations demonstrate that the turbulent wake and vortex ring states are unstable regimes for a rotor with constant loading and that these states, after a complicated transient phase, settle to a steady state. Copyright © 1998 John Wiley & Sons, Ltd.
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a model for unsteady rotor aerodynamics
Journal of Wind Engineering and Industrial Aerodynamics, 1995Co-Authors: Jens Nørkær Sørensen, Carsten Weber KockAbstract:Abstract An aerodynamic model for the simulation of unsteady flow past rotors of wind turbines is presented. The model consists of solving the unsteady, axisymmetric Euler or Navier-Stokes equations by a finite-difference method subject to volume forces determined from tabulated airfoil data. Results are compared to the blade-element Momentum Theory and experiments for the cases of a rotor with a prescribed constant normal load and steady as well as unsteady flows past the 2 MW Tjaereborg wind turbine. The model is found to be in better agreement with measurements than the Momentum Theory and in particular excellent agreement is obtained with dynamic in-flow phenomena from measured pitching transients.