2013
Rossetti, Antonio; Pavesi, Giorgio
Comparison of different numerical approaches to the study of the H-Darrieus turbines start-up Journal Article
In: Renewable Energy, vol. 50, pp. 7-19, 2013.
Abstract | BibTeX | Tags: 3D effects, BEM, CFD, Darrieus, Self-start, VAWT
@article{Rossetti2013b,
title = {Comparison of different numerical approaches to the study of the H-Darrieus turbines start-up},
author = {Antonio Rossetti and Giorgio Pavesi},
year = {2013},
date = {2013-01-01},
urldate = {2013-01-01},
journal = {Renewable Energy},
volume = {50},
pages = {7-19},
abstract = {Self-start capability is an important feature of wind turbines. It allows to obtain simpler and cheaper turbines not actively controlled. Different approaches to describe the self-start of an H-blade Darrieus rotor are presented and compared in the present work. The Blade Element Momentum (BEM) approach was compared with two and three-dimensional CFD simulations. The tip-speed ratio versus power coefficient curves and the evolution of the trust forces over a blade revolution highlighted the limits and the strengths of each approach.The BEM model showed remarkable limits to describe to describe the self-start behaviour of the tested geometry. The principal limits of the BEM approach can be ascribed to the absence of well documented aerofoil databases for low Reynolds number and the inadequate modelling of dynamics effects. The 2D simulation allowed to highlight the unsteady features of the flow fields, and the presence of a complex vortices pattern which interact with the blade. Furthermore the comparison between 2D and 3D data demonstrated the importance of 3D effects such as secondary flows and tip effects. These effects were proved to have a positive effect on start-up, increasing the torque characteristic for tip-speed ratio of 1. The start-up capability of H-Darrieus appears to be influenced by many different factors, which include secondary flows, three-dimensional aerodynamic effects and the finite aspect-ratio of the blades. ?? 2012 Elsevier Ltd.},
keywords = {3D effects, BEM, CFD, Darrieus, Self-start, VAWT},
pubstate = {published},
tppubtype = {article}
}
Self-start capability is an important feature of wind turbines. It allows to obtain simpler and cheaper turbines not actively controlled. Different approaches to describe the self-start of an H-blade Darrieus rotor are presented and compared in the present work. The Blade Element Momentum (BEM) approach was compared with two and three-dimensional CFD simulations. The tip-speed ratio versus power coefficient curves and the evolution of the trust forces over a blade revolution highlighted the limits and the strengths of each approach.The BEM model showed remarkable limits to describe to describe the self-start behaviour of the tested geometry. The principal limits of the BEM approach can be ascribed to the absence of well documented aerofoil databases for low Reynolds number and the inadequate modelling of dynamics effects. The 2D simulation allowed to highlight the unsteady features of the flow fields, and the presence of a complex vortices pattern which interact with the blade. Furthermore the comparison between 2D and 3D data demonstrated the importance of 3D effects such as secondary flows and tip effects. These effects were proved to have a positive effect on start-up, increasing the torque characteristic for tip-speed ratio of 1. The start-up capability of H-Darrieus appears to be influenced by many different factors, which include secondary flows, three-dimensional aerodynamic effects and the finite aspect-ratio of the blades. ?? 2012 Elsevier Ltd.
2012
Bianchi, Nicola; Bolognani, Silverio; Fornasiero, Emanuele; Morandin, Mattia; Pavesi, Giorgio
Optimal drive and machine sizing for a self starting, vertical axis, low power wind generator Proceedings Article
In: 2012 IEEE International Energy Conference and Exhibition, ENERGYCON 2012, pp. 178-183, ieeexplore.ieee.org, 2012, ISBN: 9781467314541.
Abstract | Links | BibTeX | Tags: Darrieus, VAWT, Wind, Wind Turbine
@inproceedings{pop00023,
title = {Optimal drive and machine sizing for a self starting, vertical axis, low power wind generator},
author = {Nicola Bianchi and Silverio Bolognani and Emanuele Fornasiero and Mattia Morandin and Giorgio Pavesi},
url = {http://ieeexplore.ieee.org/document/6347747/ http://ieeexplore.ieee.org/abstract/document/6347747/},
doi = {10.1109/EnergyCon.2012.6347747},
isbn = {9781467314541},
year = {2012},
date = {2012-01-01},
urldate = {2012-01-01},
booktitle = {2012 IEEE International Energy Conference and Exhibition, ENERGYCON 2012},
pages = {178-183},
publisher = {ieeexplore.ieee.org},
abstract = {This paper presents a comparison of different design choices in small wind power systems design. A vertical axis wind turbine is considered,to take advantage of the fact that it is omni–directional, i.e. it can accept wind from any direc- tion. The vertical axis turbine that has been used is a type of straight–bladed Darrieus turbine coupled with a Savonius turbine, in order to built a self starting turbine. To chose the electric generator with its drive, an economic analysis is carried out on the basis of generator, power converter and me- chanical system costs. The optimal ratings are found on the basis of the maximum profit over payback time. An Interior Permanent Magnet (IPM) generator and a Surface Permanent Magnet (SPM) generator are compared. The IPM generator can be driven in the flux weakening region, exploiting higher turbine rotation speeds. The paper shows that economic ad- vantages are obtained using an IPM generator, optimized together with the power converter. 1.},
keywords = {Darrieus, VAWT, Wind, Wind Turbine},
pubstate = {published},
tppubtype = {inproceedings}
}
This paper presents a comparison of different design choices in small wind power systems design. A vertical axis wind turbine is considered,to take advantage of the fact that it is omni–directional, i.e. it can accept wind from any direc- tion. The vertical axis turbine that has been used is a type of straight–bladed Darrieus turbine coupled with a Savonius turbine, in order to built a self starting turbine. To chose the electric generator with its drive, an economic analysis is carried out on the basis of generator, power converter and me- chanical system costs. The optimal ratings are found on the basis of the maximum profit over payback time. An Interior Permanent Magnet (IPM) generator and a Surface Permanent Magnet (SPM) generator are compared. The IPM generator can be driven in the flux weakening region, exploiting higher turbine rotation speeds. The paper shows that economic ad- vantages are obtained using an IPM generator, optimized together with the power converter. 1.
2010
Castelli, Marco Raciti; Pavesi, Giorgio; Battisti, Lorenzo; Benini, Ernesto; Ardizzon, Guido
Modeling Strategy and Numerical Validation for a Darrieus Vertical Axis Micro-Wind Turbine Proceedings Article
In: International Mechanical Engineering Congress & Exposition (IMECE2010), pp. pp. 409 - 418, American Society of Mechanical Engineers (ASME), 2010, ISBN: 9780791844441.
Abstract | Links | BibTeX | Tags: Darrieus, mesh, Numerical simulation, RANS
@inproceedings{Castelli2010,
title = {Modeling Strategy and Numerical Validation for a Darrieus Vertical Axis Micro-Wind Turbine},
author = {Marco Raciti Castelli and Giorgio Pavesi and Lorenzo Battisti and Ernesto Benini and Guido Ardizzon},
url = {https://doi.org/10.1115/IMECE2010-39548},
doi = {10.1115/IMECE2010-39548},
isbn = {9780791844441},
year = {2010},
date = {2010-01-01},
booktitle = {International Mechanical Engineering Congress & Exposition (IMECE2010)},
volume = {Vol. 7},
issue = {IMECE2010-39548},
pages = {pp. 409 - 418},
publisher = {American Society of Mechanical Engineers (ASME)},
abstract = {This paper presents a model for the evaluation of optimal spatialŋrid node distribution in the CFD analysis of a Darrieus verticalnaxis micro wind turbine, by analyzing the trends over a 360� rotationnof some indicators of near-blade mesh quality. To this purpose, ancomplete validation campaign has been conducted through a systematicncomparison of numerical simulations with wind tunnel experimentalndata. Both two-dimensional and three-dimensional grids, characterizednby average y+ values of 30 and 1, have been tested by applying somenstatistical techniques as a guidance in selecting the appropriateŋrid configuration and corresponding turbulence model. Finally, thentip downstream recirculation zone due to the finite blade extensionnand the influence of spokes have been analyzed, achieving a numericalnquantification of the influence of induced drag and spokes drag onnoverall rotor performance.},
keywords = {Darrieus, mesh, Numerical simulation, RANS},
pubstate = {published},
tppubtype = {inproceedings}
}
This paper presents a model for the evaluation of optimal spatialŋrid node distribution in the CFD analysis of a Darrieus verticalnaxis micro wind turbine, by analyzing the trends over a 360� rotationnof some indicators of near-blade mesh quality. To this purpose, ancomplete validation campaign has been conducted through a systematicncomparison of numerical simulations with wind tunnel experimentalndata. Both two-dimensional and three-dimensional grids, characterizednby average y+ values of 30 and 1, have been tested by applying somenstatistical techniques as a guidance in selecting the appropriateŋrid configuration and corresponding turbulence model. Finally, thentip downstream recirculation zone due to the finite blade extensionnand the influence of spokes have been analyzed, achieving a numericalnquantification of the influence of induced drag and spokes drag onnoverall rotor performance.
