Dynamic Responses of a Floating Tidal Turbine Considering Prescribed Wave-Frequency Motion

2018 ◽  
Author(s):  
Xiaoxian Guo ◽  
Jianmin Yang ◽  
Xin Li ◽  
Wenyue Lu ◽  
Tao Peng ◽  
...  
Keyword(s):  
Response Spectra ◽  
Numerical Approach ◽  
Dynamic Responses ◽  
Dynamic Loads ◽  
Hydrodynamic Coefficients ◽  
Bending Moments ◽  
Momentum Theory ◽  
Tidal Turbine ◽  
Two Peaks ◽  
Blade Element

A numerical model based on blade element momentum theory was developed to investigate the effects of floater motion on the dynamic responses of a floating tidal turbine in this paper. SJTU-FTT, a floating tidal turbine system, was introduced. A simplified numerical approach was proposed, in which the 6-DOF motion of the floater was calculated in frequency domain in advance and then was transferred to the unsteady BEM model as inputs. The hydrodynamic coefficients including (added mass, damping, and RAOs) of the floater were presented. The response spectra of the thrust, torque and blade bending moments on the tidal turbine were discussed. Two peaks in the response spectra can be clearly identified, caused by surge and pitch motion of the floater. It was seen that the dynamic loads considering 6-DOF floater motion were much larger than the results from wave only cases.

Tidal Turbine Blades: Design and Dynamic Loads Estimation Using CFD and Blade Element Momentum Theory

2011 ◽  
Author(s):  
Ce´line Faudot ◽  
Ole G. Dahlhaug
Keyword(s):  
Wind Turbines ◽  
Operating Conditions ◽  
Dynamic Loads ◽  
Power Coefficient ◽  
Scaled Model ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Stage Of Development ◽  
Tidal Turbine ◽  
Blade Element

The interest in tidal power is constantly increasing thanks to its high predictability, the huge potential of tides and the actual need for renewable energy. It explains the emergence of many tidal turbine designs, especially in Europe, often inspired from wind turbines. All of them are at a more or less early stage of development. But because of the high density of water, environmental drag forces are very large compared with wind turbines of the same capacity. Therefore the knowledge acquired by the wind industry is certainly qualitatively useful, but it has to be reconsidered to be applicable to tidal turbines. The aim of the project presented in this paper is to create a 1 MW reference tidal turbine, whose small-scaled model has been tested in the towing tank of Marintek laboratory (Trondheim, Norway). The tests focused on dynamic loads, which are an important reason of failure, and thus will help tidal turbine designers in their work by gaining valuable experience in turbine performance in various operating conditions. The chosen turbine has a horizontal axis and two blades, which have been designed using the blade element momentum theory for a diameter of 20m. This paper states the project issues and the method used to design the blades, from the hydrodynamic properties of the hydrofoils to the computational fluid dynamic analysis. The tests on the small scaled model makes it possible to validate the concept and a comparison between efficiencies obtained analytically, experimentally and with CFD computation has been performed in this paper. The maximum power coefficient experimentally obtained is 0.427, i.e. 1.4% higher than the power coefficient obtained numerically. The blade element momentum theory is then used to estimate the loads on each blade when the rotor is subjected to regular waves of many heights and periods, with the intention of ranking the parameters of importance and introducing a fatigue analysis.

scholarly journals Comparison of synthetic turbulence approaches for blade element momentum theory prediction of tidal turbine performance and loads

2020 ◽  
Vol 145 ◽  
pp. 408-418 ◽  
Author(s):  
Michael Togneri ◽  
Grégory Pinon ◽  
Clément Carlier ◽  
Camille Choma Bex ◽  
Ian Masters
Keyword(s):  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Turbine Performance ◽  
Tidal Turbine ◽  
Blade Element

scholarly journals Blade element momentum theory for a tidal turbine

2018 ◽  
Vol 169 ◽  
pp. 215-226 ◽  
Author(s):  
C.R. Vogel ◽  
R.H.J. Willden ◽  
G.T. Houlsby
Keyword(s):  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Tidal Turbine ◽  
Blade Element

The effect of shear web on the dynamic response of a wind turbine blade subjected to actual dynamic load

2021 ◽  
pp. 146442072110152
Author(s):  
Tushar Sharma ◽  
Santanu Choudhury ◽  
V Murari ◽  
KK Shukla
Keyword(s):  
Renewable Energy ◽  
Dynamic Load ◽  
Renewable Energy Sources ◽  
Dynamic Loads ◽  
Wind Loads ◽  
Energy Sources ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Crucial Part ◽  
Blade Element

The advent of wind turbines has enabled mankind to utilize renewable energy sources for the development of power. The blade being the most crucial part and the design of the same remains a challenge since it is subjected to dynamic loads due to the rotation of the blade along with unsteady wind velocity. The prediction of the dynamic wind loads acting on the blade is a difficult task and thus this has been analyzed in the present work. Two different approaches have been proposed to predict accurately the variation of the wind loads acting on the rotor using the unsteady blade element momentum theory. The effect of gravity has also been accounted for in computing the response of the structure. The effect of the position of shear web and the number of shear webs on the response of the structure has also been analyzed in the present work.

Wind Tunnel Tests of a Model Small-scale Horizontal-axis Wind Turbine Developed from Blade Element Momentum Theory

2021 ◽  
pp. 1-16
Author(s):  
Ojing Siram ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Tunnel ◽  
Horizontal Axis ◽  
Superior Performance ◽  
Speed Ratio ◽  
Small Scale ◽  
Blade Design ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Blade Element

Abstract The small-scale horizontal-axis wind turbines (SHAWTs) have emerged as the promising alternative energy resource for the off-grid electrical power generation. These turbines primarily operate at low Reynolds number, low wind speed, and low tip speed ratio conditions. Under such circumstances, the airfoil selection and blade design of a SHAWT becomes a challenging task. The present work puts forward the necessary steps starting from the aerofoil selection to the blade design and analysis by means of blade element momentum theory (BEMT) for the development of four model rotors composed of E216, SG6043, NACA63415, and NACA0012 airfoils. This analysis shows the superior performance of the model rotor with E216 airfoil in comparison to other three models. However, the subsequent wind tunnel study with the E216 model, a marginal drop in its performance due to mechanical losses has been observed.

scholarly journals Accurate loads and velocities on low solidity wind turbines using an improved Blade Element Momentum model

2020 ◽  
Author(s):  
Yassine Ouakki ◽  
Abdelaziz Arbaoui
Keyword(s):  
Drag Force ◽  
Wind Turbines ◽  
Solution Method ◽  
Turbine Blades ◽  
Accurate Prediction ◽  
Accurate Estimation ◽  
Complex Nature ◽  
Momentum Theory ◽  
Far Wake ◽  
Blade Element

Abstract. The accurate prediction of loadings and velocities on a wind turbine blades is essential for the design and optimization of wind turbines rotors. However, the classical BEM still suffer from an inaccurate prediction of induced velocities and loadings, even if the classical correction like stall delay effect and tip loss correction are used. For low solidity rotors, the loadings are generally over-predicted in the tip region, since the far wake expansion is not accurately accounted for in the one-dimensional (1D) momentum theory. The 1D dimensional momentum theory supposes that the far wake axial induction is equal to twice the axial induction in the rotor plane, which results in an under-estimation of the axial induction factor in the tip region. Considering the complex nature of the flow around a rotating blade, the accurate estimation of 3D effects is still challenging, since most stall delay models still often tend to under-predict or over-predict the loadings near the root region. As for the solution method for the classical BEM equation, the induced velocities are computed accounting for the drag force. However, according to the Kutta-Joukowski theorem, the induced velocities on a blade element are only created by lift force. Accounting for drag force when solving the BEM will result in an over-estimation of the axial induction factor, while the tangential induction factor is under-estimated. To improve the accuracy of the BEM method, in this paper, the 1D momentum theory is corrected using a new far wake expansion model to take into account the radial flow effect. The blade element theory is corrected for three-dimensional effects through an improved stall delay model. An improved solution method for the BEM equations respecting the Kutta-Joukowski theorem is proposed. The improved BEM model is used to estimate the aerodynamic loads and velocities on the National Renewable Energy Laboratory Phase VI rotor blades. The results of this study show that the proposed BEM model gives an accurate prediction of the loads and velocities compared to the classical BEM model.

scholarly journals Aerodynamic analysis of multirotor vehicles using a higher-order potential flow method

2021 ◽  
Author(s):  
Devin F. Barcelos
Keyword(s):  
Performance Prediction ◽  
Potential Flow ◽  
Higher Order ◽  
Theory Approach ◽  
Blade Element Momentum Theory ◽  
Flow Method ◽  
Momentum Theory ◽  
Radial Loading ◽  
Rotational Direction ◽  
Blade Element

A higher-order potential flow method is adapted for the aerodynamic performance prediction of small rotors used in multirotor unmanned aerial vehicles. The method uses elements of distributed vorticity which results in numerical robustness with both a prescribed and relaxed wake representation. The radial loading and wake shapes of a rotor in hover were compared to experiment to show strong agreement for three disk loadings. The advancing flight performance prediction of a single rotor was compared to a single rotor was compared to a blade element momentum theory based approach and to experiment. Comparison showed good thrust and power agreement with experiment across a range of advance ratios and angles of attack. Prediction in descending flights showed improvements in comparison to the blade element momentum theory approach. The model was extended to a quadrotorm configuration showing the differences associated to vehicle orientation and rotor rotational direction.

scholarly journals Methodology for the engineering calculation of flaps on Wind Turbines using BEM codes

2016 ◽  
Author(s):  
Maria Aparicio-Sanchez ◽  
Alvaro Gonzalez-Salcedp ◽  
Sugoi Gomez-Iradi ◽  
Xabier Munduate
Keyword(s):  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Engineering Calculation ◽  
Root Effect ◽  
Validation And Verification ◽  
Momentum Theory ◽  
Aerodynamic Control ◽  
Control Devices ◽  
Circulation Theory ◽  
Blade Element

Abstract. Aeroelastic codes based on Blade Element Momentum theory are the standard used by many wind turbine designers. These codes usually include models and corrections for unsteady aerodynamics, tip and root effect, tower shadow and other effects. In general, this kind of codes does not include models to adequately simulate aerodynamic control devices. This paper presents a method to take into account the unsteady contributions due to the flap motion (based on indicial models) and the spanwise effects (based on circulation theory), in order to simulate flaps on the blades. This method can be included in BEM codes in general and it could also be applied to another kind of control devices. The validation and verification show the accuracy of this method using experimental data for two-dimensional unsteady cases, and CFD for three-dimensional steady and unsteady cases.

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