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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.
Angel Sanz-Andrés
exaly +3 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.
John Dabiri
exaly +4 more sources
The Lanchester–Betz–Joukowsky limit
Wind Energy, 2007 AbstractThe 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. In 1976, Bergey showed that the British scientist Lanchester derived the same maximum already in 1915. Betz and Lanchester were representatives of leading aerodynamic research schools in
exaly +2 more sources
Refined Betz limit for rotors with a finite number of blades
Wind Energy, 2008 AbstractThe criterion of Betz for optimum rotors with a finite number of blades is revisited and used to determine the performance of wind turbines. The Betz criterion states that ideal efficiency is obtained when the distribution of circulation along the blade produces a rigidly helicoid wake that moves in the direction of its axis with a constant ...
Jens Nørkær Sørensen, Valery Okulov
exaly +2 more sources
A numerical proof of the Betz–Joukowsky limit
Renewable EnergyAccording to the Betz–Joukowsky limit, the maximum power coefficient of a wind turbine is 16/27. This limit is obtained assuming a priori that the disk is radially uniformly-loaded. In other words, the proof of the limit does not evaluate the optimum type of the load distribution, but it directly speculates that radially uniform load is the optimal one.
Rodolfo Bontempo, Marcello Manna
exaly +3 more sources
Limit cases for rotor theories with Betz optimization
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 ...
Valery Okulov
exaly +2 more sources
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
doaj +1 more source
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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