Results 1 to 10 of about 35,990 (188)
The extended Betz–Lanchester limit [PDF]
Renewable Energy, 2005 A proposal for an extended formulation of the power coefficient of a wind turbine is presented. This new formulation is a generalization of the Betz–Lanchester expression for the power coefficient as function of the axial deceleration of the wind speed provoked by the wind turbine in operation.
Cuerva Tejero, Alvaro +1 more
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Limit cases for rotor theories with Betz optimization [PDF]
Journal of Physics: Conference Series, 2014 A complete analytical formulation of the vortex approach for the rotor with an ideal load distribution under Betz optimal condition needs some additional assumption about a correct choice of the helical pitch for vortex sheets in the rotor wake. An examination of the three evident assumptions (the pitch is independent from velocities induced by the ...
Okulov, Valery
core +5 more sources
Theoretical framework to surpass the Betz limit using unsteady fluid mechanics [PDF]
Physical Review Fluids, 2020 The Betz limit expresses the maximum proportion of the kinetic energy flux incident on an energy conversion device that can be extracted from an unbounded flow. The derivation of the Betz limit requires an assumption of steady flow through a notional actuator disk that is stationary in the streamwise direction.
Dabiri, John O.
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Nature’s Wind Turbines: The Measured Aerodynamic Efficiency of Spinning Seeds Approaches Theoretical Limits [PDF]
Biomimetics, 2022 This paper describe a procedure to measure experimentally the power coefficient, Cp, of winged seeds, and apply this technique to seeds from the Norway maple (Acer platanoides). We measure Cp=56.9±2% at a tip speed ratio of 3.21±0.06.
Timothy C. A. Molteno
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The Betz-Joukowsky limit for the maximum power coefficient of wind turbines [PDF]
, 2009 The article addresses to a history of an important scientific result in wind energy. The maximum efficiency of an ideal wind turbine rotor is well known as the ‘Betz limit’, named after the German scientist that formulated this maximum in 1920. Also Lanchester, a British scientist, is associated with this limit, but his analysis relies on assumptions ...
Okulov, Valery, van Kuik, G.A.M.
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Misled by Betz and unsteady flow
International Marine Energy Journal, 2022 A turbine array is an adjustable flow resistance R placed in a tidal channel. Ideally, it is designed and operated to maximise energy yield. Garrett & Cummins (2005), using optimal control theory applied to the RCelement channel (R) and basin (C ...
Peter F. Pelz +2 more
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A Study of a Darrieus Vertical Axis Wind Turbine with a guiding nozzle [PDF]
E3S Web of Conferences, 2020 This paper presents the results from an experimental study of a Vertical Axis Wind turbine model with a guiding nozzle. The geometry of the nozzle is synthesized by an original methodology.
Obretenov Valentin, Tliev Rossen
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Optimal performance of actuator disc models for horizontal-axis turbines
Frontiers in Energy Research, 2022 This study analyzes actuator disc (AD) models of horizontal-axis turbines to determine optimal performance, defined as the maximum power extracted at any tip speed ratio.
David H. Wood, Mohamed M. Hammam
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Meteorologische Zeitschrift, 2021 How much wind energy does the atmosphere generate, and how much of it can at best be used as renewable energy? This review aims to give physically-based answers to both questions, providing first-order estimates and sensitivities that are consistent with
Axel Kleidon
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Wind Turbine Performance in Very Large Wind Farms: Betz Analysis Revisited
Energies, 2020 The theoretical limit for wind turbine performance, the so-called Betz limit, arises from an inviscid, irrotational analysis of the streamtube around an actuator disk.
Jacob R. West, Sanjiva K. Lele
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