New Empirical Relationship between Thrust Coefficient and Induction Factor for the Turbulent Windmill State

Buhl, Michael

doi:10.2172/15016819

Cited by 159 publications

(154 citation statements)

References 2 publications

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“…In the present study, a semi-analytical model is used to determine the wake surface S W in Equation (2). The wake is defined as a generalised helicoidal surface with distributions of axial pitch and radial expansion of the streamtube downstream of the rotor that are consistent with the operating mode of hydrokinetic turbines.…”

Section: Trailing Wake Modelmentioning

confidence: 99%

“…In the blade wake, trailing vortices are convected downstream with velocity given as the average of the onset flow speed and of the velocity perturbation induced by the wake itself, v w . A boundary integral representation of v w is obtained by taking the gradient of the velocity potential Equation (2). Here, an approximated representation of this velocity field across the fluid region of interest is obtained by using BIEM to evaluate v w at the rotor plane and imposing a linear variation downstream to match a given farfield distribution.…”

Section: Trailing Wake Modelmentioning

confidence: 99%

“…It is thus not surprising that Blade Element Momentum methods (simply, BEM) originally developed for wind turbines are extensively used for analysis and design of tidal and ocean current turbines, see e.g., [1]. BEM provides fast and reliable estimates of turbine performance if suitable tuning is applied to overcome important methodology weaknesses [2,3]. Specifically, blade loading is derived by prescribed lift and drag properties of two-dimensional profiles and semi-empirical three-dimensional flow corrections are necessary to account for blade tip effects, blade/hub interaction, number of blades.…”

Section: Introductionmentioning

confidence: 99%

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Marine Turbine Hydrodynamics by a Boundary Element Method with Viscous Flow Correction

Salvatore¹,

Sarichloo²,

Calcagni³

2018

JMSE

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A computational methodology for the hydrodynamic analysis of horizontal axis marine current turbines is presented. The approach is based on a boundary integral equation method for inviscid flows originally developed for marine propellers and adapted here to describe the flow features that characterize hydrokinetic turbines. For this purpose, semi-analytical trailing wake and viscous flow correction models are introduced. A validation study is performed by comparing hydrodynamic performance predictions with two experimental test cases and with results from other numerical models in the literature. The capability of the proposed methodology to correctly describe turbine thrust and power over a wide range of operating conditions is discussed. Viscosity effects associated to blade flow separation and stall are taken into account and predicted thrust and power are comparable with results of blade element methods that are largely used in the design of marine current turbines. The accuracy of numerical predictions tends to reduce in cases where turbine blades operate in off-design conditions.

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Section: Trailing Wake Modelmentioning

confidence: 99%

Section: Trailing Wake Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Marine Turbine Hydrodynamics by a Boundary Element Method with Viscous Flow Correction

Salvatore¹,

Sarichloo²,

Calcagni³

2018

JMSE

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“…where dT denotes the local thrust on the blade element and 2 dA rdr   is the cross-sectional area of (13) or 7 the hub radius. The corrected influence factors for Eqs.…”

Section: Cos ( )mentioning

confidence: 99%

“…The thrust coefficient in Eq. (13) represents the local thrust coefficient, and it can be derived from the blade element theory as follows [14]: 7 the hub radius. The corrected influence factors for Eqs.…”

Section: Cos ( )mentioning

confidence: 99%

Prediction of Aerodynamic Loads for NREL Phase VI Wind Turbine Blade in Yawed Condition

Ryu¹,

Kang²,

Seo³

et al. 2016

International Journal of Aeronautical and Space Sciences

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Aerodynamic loads for a horizontal axis wind turbine of the National Renewable Energy Laboratory (NREL) Phase VI rotor in yawed condition were predicted by using the blade element momentum theorem. The classical blade element momentum theorem was complemented by several aerodynamic corrections and models including the Pitt and Peters' yaw correction, Buhl's wake correction, Prandtl's tip loss model, Du and Selig's three-dimensional (3-D) stall delay model, etc. Changes of the aerodynamic loads according to the azimuth angle acting on the span-wise location of the NREL Phase VI blade were compared with the experimental data with various yaw angles and inflow speeds. The computational flow chart for the classical blade element momentum theorem was adequately modified to accurately calculate the combined functions of additional corrections and models stated above. A successive under-relaxation technique was developed and applied to prevent possible failure during the iteration process. Changes of the angle of attack according to the azimuth angle at the specified radial location of the blade were also obtained. The proposed numerical procedure was verified, and the predicted data of aerodynamic loads for the NREL Phase VI rotor bears an extremely close resemblance to those of the experimental data.

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Windmill Brake State Models Used in Predicting Wind Turbine Performance

Pratumnopharat¹,

Leung²

2016

Alternative Energy and Shale Gas Encyclopedia

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New Empirical Relationship between Thrust Coefficient and Induction Factor for the Turbulent Windmill State

Cited by 159 publications

References 2 publications

Marine Turbine Hydrodynamics by a Boundary Element Method with Viscous Flow Correction

Marine Turbine Hydrodynamics by a Boundary Element Method with Viscous Flow Correction

Prediction of Aerodynamic Loads for NREL Phase VI Wind Turbine Blade in Yawed Condition

Windmill Brake State Models Used in Predicting Wind Turbine Performance

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