Results 221 to 230 of about 75,283 (262)

Air-speed/Wing-tip Speed Ratios of Insect Flight

Nature, 1950
I HAVE made measurements of the wing movements of the tsetse-fly Glossina palpalis R-D. and other Glossina species in free flight, using a stroboscope and a large series of ‘Arditron’ flash photographs (duration about 1–2 microseconds). The wing-beat frequency for G. palpalis is 120 cycles per second; but investigation shows that the relative speeds of
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An Actuator Disc Theory for the Shed Wake at Low Tip Speed Ratios

SAE Technical Paper Series, 1965
<div class="htmlview paragraph">A model of flow through a helicopter rotor, suitable for estimating effects of shed wake in hovering and at low tip speed ratios, is described. With this method, the result for aerodynamic damping of blade bending oscillations is in agreement with more elaborate theories.
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Wind energy from turbulence: Constant tip speed ratio operation

Solar Energy, 1985
Abstract The ability of a wind machine, operating at constant tip speed ratio, to extract power from the turbulent eddy fluctuations in the wind is examined. A model is constructed relating the inertia of the machine to its ability to follow the fluctuations. The model includes a transfer function from which a cutoff frequency can be predicted.
Manwell, JF, KIRCHHOFF, RH
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The velocity of the tip vortex of a horizontal-axis wind turbine at high tip speed ratio

Renewable Energy, 1998
An equation is derived for the streamwise velocity of the tip vortex of a horizontal-axis wind turbine as the pitch of the vortex tends to zero. The equation is applicable at high tip speed ratios provided the vortex core remains of constant size and there is no flow along the vortex axis.
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Maximum wind turbine performance at low tip speed ratio

Journal of Renewable and Sustainable Energy, 2015
Wind turbines can approach the Betz-Joukowsky limit on maximum power only at sufficiently high tip speed ratio: in practice, for ratios in excess of about seven. This paper analyses the performance of a turbine with an infinite number of blades as the tip speed ratio decreases to zero, beginning with the two traditional ways of determining the maximum ...
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Online estimation of the power coefficient versus tip-speed ratio curve of wind turbines

IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013
Wind turbines are one of the main sources of renewable energy worldwide. Although large wind turbines in the MW range are popular, small wind turbines of several kW can also have a valuable contribution since they can be installed in a more decentralized manner. However, the energy yield of these small wind turbines still needs improvement.
Jeroen D. M. De Kooning, Louis Gevaert, Jan Van de Vyver, Tine L. Vandoorn, Lieven Vandevelde   +4 more
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Study of Tip Flows in High Hub-to-Tip Ratio Axial Compressors at Low Speed With Varying Tip Gaps, Inflow Conditions and Tip Shapes

Volume 7: Turbomachinery, Parts A, B, and C, 2010
The present study involves simulation of a single compressor rotor with a high hub-to-tip ratio blade. The study includes the effect of variation of tip gap, of tip shapes and of inlet axial velocity profiles, with inflows simulated similar to that of a typical rear stage environment of a multi-stage axial compressor. Numerical studies were carried out
Bhaskar Roy, A. M. Pradeep, A. Suzith, Dinesh Bhatia, Aditya Mulmule   +4 more
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Effects of tip speed ratio on wind turbine wake meandering

Journal of Fluid Mechanics
This study utilises large-eddy simulation with the actuator line model to examine the effects of the tip speed ratio (TSR) on the wake-meandering characteristics of a wind turbine in uniform and turbulent inflows. It is shown that as the TSR grows, the onset position of the wake meandering moves closer to the rotor, and the magnitude of wake ...
Yan Wang, Guihua Zhao, Guoliang Liu, Yongze Zhou, Mingwei Ge, Zhen Ouyang, Zijing Ding, Ruifeng Hu   +7 more
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Tip speed ratio and Pitch angle control based on ANN for putting variable speed WTG on MPP

2016 Eighteenth International Middle East Power Systems Conference (MEPCON), 2016
The control of a variable-speed wind turbine below the rated wind speed is achieved by controlling the generator. The main goal is to maximize the wind power capture at variable wind speed which can be achieved by adjusting the turbine speed in such a way that the optimal tip speed ratio λ opt is maintained. For higher than rated wind speeds but below
Hassan H. El-Tamaly, Ayman Yousef Nassef
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Tip speed ratio control of wind turbine generating system connected in series

2011 International Conference on Electrical Machines and Systems, 2011
Experimental and simulated investigations of tip speed ratio control for a wind turbine generating system consisting of series connected two wind turbine/generators and a current-source thyristor inverter are carried out. It is confirmed that tip speed ratios of the individual turbines can be controlled almost constant when wind velocities fluctuated ...
Hiroyuki Yokoyama, Fujio Tatsuta, Shoji Nishikata   +2 more
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