Inclusion of a Simple Dynamic Inflow Model in the Blade Element Momentum Theory for Wind Turbine Application

Bem Theory ◽

It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT) is a function of the number of blades B, the tip speed ratio λr (blade tip speed/wind free-stream velocity) and the lift to drag ratio (CL/CD) of the airfoil sections of the blade. The previous studies have shown that Blade Element Momentum (BEM) theory is capable of evaluating the steady-state performance of wind turbines, in particular it can provide a reasonably good estimate of generated power at a given wind speed. However in more realistic applications, wind turbine operating conditions change from time to time due to variations in wind velocity and the aerodynamic forces change to new steady-state values after the wake settles to a new equilibrium whenever changes in operating conditions occur. The goal of this paper is to modify the quasi-steady BEM theory by including a simple dynamic inflow model to capture the unsteady behavior of wind turbines on a larger time scale. The output power of the wind turbines is calculated using the improved BEM method incorporating the inflow model. The computations are performed for the original NREL Phase II and Phase III turbines and the Risoe turbine all employing the S809 airfoil section for the turbine blades. It is shown by a simple example that the improved BEM theory is capable of evaluating the wind turbine performance in practical situations where operating conditions often vary in time.

Modeling and simulation of forces applied to the horizontal axis wind turbine rotors by the vortex method coupled with the method of the blade element

International Journal of Power Electronics and Drive Systems (IJPEDS) ◽

10.11591/ijpeds.v12.i1.pp413-420 ◽

2021 ◽

Vol 12 (1) ◽

pp. 413

Author(s):

Ibtissem Barkat ◽

Abdelouahab Benretem ◽

Fawaz Massouh ◽

Issam Meghlaoui ◽

Ahlem Chebel

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Wind Farms ◽

Vortex Method ◽

Operating Conditions ◽

Horizontal Axis ◽

Rotor Blades ◽

Good Representation ◽

This article aims to study the forces applied to the rotors of horizontal axis wind turbines. The aerodynamics of a turbine are controlled by the flow around the rotor, or estimate of air charges on the rotor blades under various operating conditions and their relation to the structural dynamics of the rotor are critical for design. One of the major challenges in wind turbine aerodynamics is to predict the forces on the blade as various methods, including blade element moment theory (BEM), the approach that is naturally adapted to the simulation of the aerodynamics of wind turbines and the dynamic and models (CFD) that describes with fidelity the flow around the rotor. In our article we proposed a modeling method and a simulation of the forces applied to the horizontal axis wind rotors turbines using the application of the blade elements method to model the rotor and the vortex method of free wake modeling in order to develop a rotor model, which can be used to study wind farms. This model is intended to speed up the calculation, guaranteeing a good representation of the aerodynamic loads exerted by the wind.

Geometrical Design of a Rotor Blade for a Small Scale Horizontal Axis Wind Turbine

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.c5036.098319 ◽

2019 ◽

Vol 8 (3) ◽

pp. 3390-3400

Keyword(s):

Wind Turbine ◽

Rotor Blade ◽

Operating Conditions ◽

Horizontal Axis ◽

Small Scale ◽

Geometrical Properties ◽

Momentum Theory ◽

Bem Theory ◽

In the present study, Blade Element Momentum theory (BEMT) has been implemented to heuristically design a rotor blade for a 2kW Fixed Pitch Fixed Speed (FPFS) Small Scale Horizontal Axis Wind Turbine (SSHAWT). Critical geometrical properties viz. Sectional Chord ci and Twist distribution θTi for the idealized, optimized and linearized blades are analytically determined for various operating conditions. Results obtained from BEM theory demonstrate that the average sectional chord ci and twist distribution θTi of the idealized blade are 20.42% and 14.08% more in comparison with optimized blade. Additionally, the employment of linearization technique further reduced the sectional chord ci and twist distribution θTi of the idealized blade by 17.9% and 14% respectively, thus achieving a viable blade bounded by the limits of economic and manufacturing constraints. Finally, the study also reveals that the iteratively reducing blade geometry has an influential effect on the solidity of the blade that in turn affects the performance of the wind turbine.

Assessment of a Modified Blade Element Momentum Methodology for Diffuser Augmented Wind Turbines

Volume 7: Fluids Engineering ◽

10.1115/imece2017-70288 ◽

2017 ◽

Author(s):

Stavros N. Leloudas ◽

Georgios N. Lygidakis ◽

Ioannis K. Nikolos

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Power Output ◽

Correction Model ◽

Short Period ◽

Turbine Design ◽

The Impact ◽

Bem Theory ◽

The Blade Element Momentum (BEM) theory is nowadays the cornerstone of the horizontal axis wind turbine design, as its application allows for the accurate aerodynamic simulation and power output prediction of wind turbine rotors in a remarkably short period of time. Therefore, efforts have been made for the extension of the classic BEM theory to the performance analysis of Diffuser Augmented Wind Turbines (DAWTs) as well. In this study, the development and assessment of such an in-house BEM code are presented. The proposed computational model is based on the modification of the momentum part of the classical BEM theory; thus, it is capable to account for the diffuser’s effect on the calculation of the axial and tangential induction factors, through the utilization of the velocity speed-up distribution over the rotor plane of the unloaded diffuser. Furthermore, a detailed Glauert’s correction model, which employs Buhl’s modification, specially tailored for the DAWT case is included, to deal with the high values of the axial induction factor. The accuracy of the model is assessed against numerical and experimental results available in the literature, while the impact of the Prandtl’s tip loss correction model on the rotor’s predicted power output is also examined.

Assessment of the Performance of Various Airfoil Sections on Power Generation From a Wind Turbine Using the Blade Element Momentum Theory

ASME 2013 7th International Conference on Energy Sustainability ◽

10.1115/es2013-18024 ◽

2013 ◽

Cited By ~ 1

Author(s):

Xiaomin Chen ◽

Ramesh Agarwal

Keyword(s):

Wind Turbine ◽

Phase Ii ◽

Turbine Rotor ◽

Phase Iii ◽

Speed Ratio ◽

Stream Velocity ◽

Airfoil Section ◽

Flat Back ◽

It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT) is a function of the number of blades B, the tip speed ratio λ (blade tip speed/wind free stream velocity) and the lift to drag ratio (CL/CD) of the airfoil sections of the blade. The airfoil sections used in HAWT are generally thick airfoils such as the S, DU, FX, Flat-back and NACA 6-series of airfoils. These airfoils vary in (CL/CD) for a given B and λ, and therefore the power generated by HAWT for different blade airfoil sections will vary. The goal of this paper is to evaluate the effect of different airfoil sections on HAWT performance using the Blade Element Momentum (BEM) theory. In this study, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and λ and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine rotor diameter.

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

Structural Performance of 14m HAWT blade through CFD

10.35940/ijitee.c8928.019320 ◽

2020 ◽

Vol 9 (3) ◽

pp. 1846-1955

Keyword(s):

Wind Turbine ◽

Structural Integrity ◽

Operating Conditions ◽

Power Coefficient ◽

Speed Ratio ◽

Element Analysis ◽

Process Verification ◽

Efficient Extraction ◽

An alternative method used in generating energy is with the help of wind turbines utilizing power from the winds. The efficient extraction of energy hinges on the geometry and structure of the blade. The blade of wind turbine encounters high operational loads and undergoes fluctuating conditions of environment. The proposed work comprises of creating an exact model using CAD applications which includes the optimized geometry of the blade in addition with process verification of structural integrity, under several operating conditions by the means of finite element analysis. The prime motive of the proposed study is to check and evaluate the reliability of the blades by developing the entire geometry of the blade and performing failure analysis by altering load conditions. The construction of blade geometry is done by implementing the blade element momentum theory (BEMT) in order to retrieve the ultimate power coefficient at the required tip speed ratio of 7.05 by the means of optimization process. The NACA 63(4)-221 airfoil is used to create the primary design of blade. Blade with 14 m length has been taken for the present work for RRB V27-225 kW HAWT (horizontal axis wind turbine blade), which is an exclusive design of the blade. In order to perform analysis and modeling of the blade in presence and absence of shear web, two individual materials such as carbon fiber and glass fiber are taken in account. In the case of carbon fibre with shear web, the structural strength is improved which is shown in the results.

New airfoils for micro horizontal-axis wind turbines

Journal of Engineering Research ◽

10.36909/jer.10949 ◽

2021 ◽

Author(s):

Manoj Kumar Chaudhary ◽

◽

S. Prakash ◽

Keyword(s):

Reynolds Number ◽

Wind Turbines ◽

Low Reynolds Number ◽

Horizontal Axis ◽

Speed Ratio ◽

Maximum Output ◽

Horizontal Axis Wind Turbines ◽

Low Reynolds ◽

Bem Theory

In this study, small horizontal-axis wind turbine blades operating at low wind speeds were optimized. An optimized blade design method based on blade element momentum (BEM) theory was used. The rotor radius of 0.2 m, 0.4 m and 0.6 m and blade geometry with single (W1 & W2) and multistage rotor (W3) was examined. MATLAB and XFoil programs were used to implement to BEM theory and devise a six novel airfoil (NAF-Series) suitable for application of small horizontal axis wind turbines at low Reynolds number. The experimental blades were developed using the 3D printing additive manufacturing technique. The new airfoils such as NAF3929, NAF4420, NAF4423, NAF4923, NAF4924, and NAF5024 were investigated using XFoil software at Reynolds numbers of 100,000. The investigation range included tip speed ratios from 3 to 10 and angle of attacks from 2° to 20°. These parameters were varied in MATLAB and XFoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient and lift-to-drag ratio. The cut-in wind velocity of the single and multistage rotors was approximately 2.5 & 3 m/s respectively. The optimized tip speed ratio, axial displacement and angle of attack were 5.5, 0.08m & 6° respectively. The proposed NAF-Series airfoil blades exhibited higher aerodynamic performances and maximum output power than those with the base SG6043 and NACA4415 airfoil at low Reynolds number.

Modeling of Rain Drop Erosion in a Multi-MW Wind Turbine

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2015-42174 ◽

2015 ◽

Cited By ~ 11

Author(s):

Alessandro Corsini ◽

Alessio Castorrini ◽

Enrico Morei ◽

Franco Rispoli ◽

Fabrizio Sciulli ◽

...

Keyword(s):

Wind Turbine ◽

Stokes Equations ◽

Turbine Blades ◽

Operating Conditions ◽

Design Stage ◽

Base Line ◽

Relevant Effect ◽

The Impact ◽

Rain Erosion

The actual strategy in offshore wind energy development is oriented to the progressive increase of the turbine diameter as well as the per unit power. Among many pioneering technological and aerodynamic issues linked to this design trend, the wind velocity at the blade tip region reaches very high values in normal operating conditions (typically between 90 to 110 m/s). In this range of velocity, the rain erosion phenomenon can have a relevant effect on the overall turbine performance in terms of power and energy production (up to 20% loss in case of deeply eroded leading edge). Therefore, as a customary approach erosion related issues are accounted for in the scheduling of the wind turbine maintenance. When offshore, on the other hand, the criticalities inherent to the cost of maintenance and operation monitoring suggest the rain erosion concerns to be tackled at the turbine design stage. In so doing, the use of computational tools to study the erosion phenomenon of wind turbines under severe meteorological conditions could define the base-line approach in the wind turbine blades design and verification. In this work, the authors present a report on numerical prediction of erosion on a 6 MW HAWT (horizontal axis wind turbine). Two different blade geometries of different aerodynamic loading, have been studied in a view to explore their sensitivity to rain erosion. The fully 3D simulations are carried out using an Euler-Lagrangian approach. Flow field simulations are carried out with the open-source code OpenFOAM, based on a finite volume approach, using Multiple Reference Frame methodology. Reynolds Averaged Navier-Stokes equations for incompressible steady flow were solved with a k-ε turbulence. An in-house code (P-Track) is used to compute the rain drops transport and dispersion, adopting the Particle Cloud Tracking approach (PCT), already validated on large industrial turbomachinery. At the impact on blade, erosion is modelled accounting for the main quantities affecting the phenomenon, which are impact velocity and material properties of the target surface. Results provide the regions of the two blades more sensitive to erosion, and the effect of the blade geometry on erosion attitude.

Analysis of Aerodynamic Performance for Wind Turbine Based on Amended Calculation of BEM Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.608-609.775 ◽

2012 ◽

Vol 608-609 ◽

pp. 775-780

Author(s):

De Tian ◽

Shuo Ming Dai ◽

Si Liu ◽

Ning Bo Wang

Keyword(s):

Wind Turbine ◽

Turbine Blades ◽

Aerodynamic Performance ◽

Wind Turbine Blades ◽

Thrust Coefficient ◽

Load Distributions ◽

Design Software ◽

Turbine Design ◽

Bem Theory ◽

Effects of tip losses, hub losses, amended attack angle, and amended thrust coefficient are taken into consideration to analyze aerodynamic performance of wind turbine blades based on the blade element momentum (BEM) theory. Based on amended calculation of BEM theory, a program code is developed by software named Matlab. Using a 1500kW wind turbine as an example, aerodynamic information, performance coefficients and blade load distributions are calculated. Compared with the well-known international wind power design software called Garrad Hassan (GH) Bladed, the results have good consistency, which further verifies amendments to the model algorithms and accuracy of the calculation. As a result, the amended calculation of BEM theory can reflect blade aerodynamic performance characteristics under actual operating condition, which has good reference and practicality for the wind turbine design and evaluation.

HAWT Rotor Design and Performance Analysis

ASME 2009 3rd International Conference on Energy Sustainability, Volume 2 ◽

10.1115/es2009-90441 ◽

2009 ◽

Cited By ~ 4

Author(s):

Emrah Kulunk ◽

Nadir Yilmaz

Keyword(s):

Performance Analysis ◽

Computer Program ◽

Wind Turbine ◽

Design Method ◽

Aerodynamic Performance ◽

Rotor Design ◽

And Performance ◽

Bem Theory ◽

In this paper, a design method based on blade element momentum (BEM) theory is explained for horizontal-axis wind turbine (HAWT) blades. The method is used to optimize the chord and twist distributions of the blades. Applying this method a 100kW HAWT rotor is designed. Also a computer program is written to estimate the aerodynamic performance of the existing HAWT blades and used for the performance analysis of the designed 100kW HAWT rotor.

Numerical Modeling of the Effects of Leading-Edge Erosion and Trailing-Edge Damage on Wind Turbine Loads and Performance

Volume 12: Wind Energy ◽

10.1115/gt2020-16310 ◽

2020 ◽

Author(s):

Francesco Papi ◽

Lorenzo Cappugi ◽

Alessandro Bianchini ◽

Sebastian Perez-Becker

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Prolonged Exposure ◽

Turbine Blades ◽

Leading Edge ◽

Future Generation ◽

Operating Conditions ◽

Wind Speeds ◽

Extreme Loads ◽

The Impact

Abstract Wind turbines often operate in challenging environmental conditions. In hot and dusty climates, wind turbine blades are constantly exposed to abrasive particles that, according to many field reports, cause significant damages to the blade’s leading edge. On the other hand, in cold climates similar effects can be caused by prolonged exposure to hail and rain. Quantifying the effects of airfoil deterioration on modern multi-MW wind turbines is crucial to correctly schedule maintenance and to forecast the potential impact on productivity. Analyzing the impact of airfoil damage on fatigue and extreme loading is also important to improve the reliability and longevity of wind turbines. However, this is a topic that has not yet been extensively investigated. In this work, a blade erosion model is developed and calibrated using Computational Fluid Dynamics (CFD). The DTU 10MW Reference Wind Turbine (RWT) is selected as the case study for the analysis, as it is representative of the typical size of the future generation wind turbines. Lift and Drag polars are generated using the developed model and a CFD numerical set-up. Power and torque coefficients are compared in idealized conditions at two wind speeds, i.e. the rated speed and one below it. Full aero-servo-elastic simulations of the turbine are conducted with the eroded polars using NREL’s BEM-based code OpenFAST. Sixty-six ten-minute simulations are performed for each stage of airfoil damage, reproducing operating conditions specified by the IEC 61400-1 power production DLC-group, including wind shear, yaw misalignment and turbulence. Performance data, fatigue and extreme loads are compared for the aeroelastic simulations, showing maximum decreases in CP of about 12% as well as reductions in fatigue and extreme loading.