scholarly journals Effects of Tip Speed Ratios on the Blade Forces of a Small H-Darrieus Wind Turbine

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4025
Author(s):  
Sajid Ali ◽  
Choon-Man Jang
Keyword(s):  
Wind Turbine ◽  
Lift Force ◽  
Stokes Equations ◽  
Aerodynamic Force ◽  
Turbine Blades ◽  
Leading Edge ◽  
Test Facility ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Optimization Approach

Lift force is an important parameter for the performance evaluation of an H-Darrieus wind turbine. The rotational direction of the streamlined force is effective on the performance of the wind turbine. In order to analyze the flow characteristics around the turbine blades in real-time, a numerical analysis using three-dimensional unsteady Reynold-averaged Navier–Stokes equations has been introduced. Experimental data were obtained from a field test facility constructed on an island in South Korea and was introduced to compare the numerical simulation results with measured data. The optimum tip speed ratio (TSR) was investigated via a multi-variable optimization approach and was determined to be 3.5 for the NACA 0015 blade profile. The turbine displays better performance with the maximum power coefficient at the optimum TSR. It is due to the delay in the flow separation from the blade surface and the relatively lower strength of the tip vortices. Furthermore, the ratio between lift and drag forces is also the highest at the optimum TSR, as most of the aerodynamic force is directly converted into lift force. For one rotation of the turbine blade at the optimum TSR, the first quarter of motion produces the highest lift as the static pressure difference is maximum at the leading edge, which helps to generate maximum lift. At a TSR less than the optimum TSR, small-lift generation is dominant, whereas at a higher TSR, large drag production is observed. Both of these lead to lower performance of the turbine. Apart from the TSR, the optimum wind angle of attack is also investigated, and the results are prepared against each TSR.

scholarly journals Design Optimization of a Multi-Megawatt Wind Turbine Blade with the NPU-MWA Airfoil Family

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3330 ◽  
Author(s):  
Jianhua Xu ◽  
Zhonghua Han ◽  
Xiaochao Yan ◽  
Wenping Song
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Weight Reduction ◽  
Stokes Equations ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Aerodynamic Performance ◽  
Wind Turbine Blade ◽  
Structural Performance ◽  
Power Coefficient

A new airfoil family, called NPU-MWA (Northwestern Polytechnical University Multi-megawatt Wind-turbine A-series) airfoils, was designed to improve both aerodynamic and structural performance, with the outboard airfoils being designed at high design lift coefficient and high Reynolds number, and the inboard airfoils being designed as flat-back airfoils. This article aims to design a multi-megawatt wind turbine blade in order to demonstrate the advantages of the NPU-MWA airfoils in improving wind energy capturing and structural weight reduction. The distributions of chord length and twist angle for a 5 MW wind turbine blade are optimized by a Kriging surrogate model-based optimizer, with aerodynamic performance being evaluated by blade element-momentum theory. The Reynolds-averaged Navier–Stokes equations solver was used to validate the improvement in aerodynamic performance. Results show that compared with an existing NREL (National Renewable Energy Laboratory) 5 MW blade, the maximum power coefficient of the optimized NPU 5 MW blade is larger, and the chord lengths at all span-wise sections are dramatically smaller, resulting in a significant structural weight reduction (9%). It is shown that the NPU-MWA airfoils feature excellent aerodynamic and structural performance for the design of multi-megawatt wind turbine blades.

Performance Improvements for a Vertical Axis Wind Turbine by Means of Gurney Flap

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Yan Yan ◽  
Eldad Avital ◽  
John Williams ◽  
Jiahuan Cui
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Performance Improvements ◽  
Gurney Flap

Abstract A numerical study was carried out to investigate the effects of a Gurney flap (GF) on the aerodynamics performance of the NACA 00 aerofoil and an associated three-blade rotor of a H-type Darrieus wind turbine. The flow fields around a single aerofoil and the vertical axis wind turbine (VAWT) rotor are studied using unsteady Reynolds-averaged Navier–Stokes equations (URANS). The height of GF ranges from 1% to 5% of the aerofoil chord length. The results show that the GF can increase the lift and lift-to-drag ratio of the aerofoil as associated with the generation of additional vortices near the aerofoil trailing edge. As a result, adding a GF can significantly improve the power coefficient of the VAWT at low tip speed ratio (TSR), where it typically gives low power production. The causing mechanism is discussed in detail, pointing to flow separation and dynamic stall delay.

scholarly journals The effect of Rotor Separation on the Performance of a Dual Rotor Wind Turbine

2021 ◽  
Author(s):  
ANTHONY ADEYANJU ◽  
Omar Mohammed ◽  
Krishpersad Manohar
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
High Energy ◽  
Separation Distance ◽  
Energy Output ◽  
Power Coefficient ◽  
Total Power ◽  
Speed Ratio ◽  
Horizontal Axis Wind Turbine ◽  
Tip Speed Ratio

This study conducted simulation and experimental analysis on a dual rotor horizontal axis wind turbine to determine the effect of rotor separation on its performance. An air study was conducted to optimize the turbine blades to a local climate of Trinidad, it was determined that a NACA 64-315 air foil would be the most optimum for the conditions. QBlade software was used for the simulation, the power flow performance for multiple iterations of wind speed was found for the design. The effect of rotor separation on the performance of the dual rotor wind turbine was studied with rotor separation 0.25 m to 3.0 m at an interval of 0.25 m and it was discovered that the smallest rotor separation 0.25 m shows the largest tip speed ratio, while the largest rotor separation distance 3m has the smallest tip speed ratio at a fan speed of 1m/s. Also, as the rotor separation decreases the power coefficient (C P ) and the total power increase, which resulted to high energy output of the DRHAWT. This result is valid for the QBlade simulations and the experimental results.

scholarly journals Numerical Investigation on the Effects of Airfoil Leading Edge Radius on the Aerodynamic Performance of H-Rotor Darrieus Vertical Axis Wind Turbine

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3794
Author(s):  
Chenguang Song ◽  
Guoqing Wu ◽  
Weinan Zhu ◽  
Xudong Zhang ◽  
Jicong Zhao
Keyword(s):  
Wind Turbine ◽  
Leading Edge ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Edge Radius ◽  
Flow Field Characteristics ◽  
Naca 0015

This paper numerically investigates the effects of airfoil leading edge radius on the aerodynamic characteristics of H-rotor Darrieus vertical axis wind turbine (VAWT). 10 modified airfoils are generated by changing the leading edge radius of the base NACA 0015 airfoil from 1%c to 9%c, respectively. A 2D unsteady Computational Fluid Dynamics (CFD) model is established and validated with the previously published experimental data. The power, torque, and flow field characteristics of the rotors are analyzed. The results indicate that the maximum and minimum power coefficient at the optimum tip speed ratio (TSR) are obtained for the LE-5%c and LE-1%c model, respectively. The best aerodynamic characteristics are determined by the LE-5%c model below the optimum TSR and the LE-3%c model beyond the optimum TSR. The torque characteristics and pressure distribution for the single blades with different airfoil leading edge radius show an obvious difference in the upwind region and a very small difference in the downwind region. Moreover, the airfoil leading edge radius influences the strength, region, and diffusion rate of the vortices, being the main reason for the observed differences in instantaneous torque coefficient and power coefficient. The vortices of the LE-1%c model are stronger, larger, and diffuse slower than those of the LE-2%c and LE-5%c model at the optimum TSR.

scholarly journals Effectiveness of Nature-Inspired Algorithms using ANFIS for Blade Design Optimization and Wind Turbine Efficiency

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 456 ◽  
Author(s):  
Md. Sarkar ◽  
Sabariah Julai ◽  
Chong Wen Tong ◽  
Siti Toha
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Power Coefficient ◽  
Design Parameters ◽  
Speed Ratio ◽  
Blade Design ◽  
Horizontal Axis Wind Turbine ◽  
Bee Colony ◽  
Maximum Value ◽  
Nature Inspired Algorithms

Blade design of the horizontal axis wind turbine (HAWT) is an important parameter that determines the reliability and efficiency of a wind turbine. It is important to optimize the capture of the energy in the wind that can be correlated to the power coefficient ( C p ) of HAWT system. In this paper, nature-inspired algorithms, e.g., ant colony optimization (ACO), artificial bee colony (ABC), and particle swarm optimization (PSO) are used to search for the blade parameters that can give the maximum value of C p for HAWT. The parameters are tip speed ratio, blade radius, lift to drag ratio, solidity ratio, and chord length. The performance of these three algorithms in obtaining the optimal blade design based on the C p are investigated and compared. In addition, an adaptive neuro-fuzzy interface (ANFIS) approach is implemented to predict the C p of wind turbine blades for investigation of algorithm performance based on the coefficient determination (R2) and root mean square error (RMSE). The optimized blade design parameters are validated with experimental results from the National Renewable Energy Laboratory (NREL). It was found that the optimized blade design parameters were obtained using an ABC algorithm with the maximum value power coefficient higher than ACO and PSO. The predicted C p using ANFIS-ABC also outperformed the ANFIS-ACO and ANFIS-PSO. The difference between optimized and predicted is very small which implies the effectiveness of nature-inspired algorithms in this application. In addition, the value of RMSE and R2 of the ABC-ANFIS algorithm were lower (indicating that the result obtained is more accurate) than the ACO and PSO algorithms.

scholarly journals Design and optimization of a small horizontal axis wind turbine using BEM theory and tip loss corrections

2021 ◽  
Vol 294 ◽  
pp. 01003
Author(s):  
Somaya Younoussi ◽  
Abdeslem Ettaouil
Keyword(s):  
Wind Turbine ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Optimization Approach ◽  
Horizontal Axis Wind Turbine ◽  
Newton’S Iterative Method ◽  
Tip Speed Ratio ◽  
De Vries ◽  
Bem Theory

In this paper, an optimization approach of a small horizontal axis wind turbine based on BEM theory including De Vries and Shen et al. tip loss corrections is proposed. The optimal blade geometry was obtained by maximizing the power coefficient along the blade using the optimal angle of attack and the optimal tip speed ratio. The Newton’s iterative method applied to axial induction factor was used to solve the problem. This study was conducted for a NACA4418 small wind turbine, at low wind velocity. Among the two used tip loss corrections, the De Vries correction was found to be the most suitable for this blade optimization method. The optimal design was obtained for a tip speed ratio of 5 and has recorded a power coefficient equal to 0.463.

scholarly journals An innovative augmentation technique of savonius wind turbine performance

2019 ◽  
Vol 44 (1) ◽  
pp. 93-112 ◽  
Author(s):  
Khaled M Youssef ◽  
Ahmed M El Kholy ◽  
Ashraf M Hamed ◽  
Nabil A Mahmoud ◽  
Ahmed M El Baz ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Peak Power ◽  
Stokes Equations ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Future Application ◽  
Speed Ratio ◽  
Ansys Fluent ◽  
Turbine Performance ◽  
Savonius Wind Turbine

This work presents an innovative technique to enhance the performance of the Savonius wind turbine. The new technique is based on introducing an upstream deflector and downstream baffle. The shape and location of both devices are optimized using a genetic algorithm. The performance of the turbine with the optimized devices is compared with the single Savonius turbine performance. The study employs the finite volume solver (ANSYS-FLUENT) to solve unsteady Reynolds Averaged Navier–Stokes equations and turbulence model equations. The optimized configuration results in much higher power coefficient than the Savonius turbine. The average peak power coefficient using both deflector and baffle is 0.47 compared to 0.24 of the Savonius turbine. The peak power coefficient of the turbine corresponds to a speed ratio close to unity. This improved performance is attributed to the favorable aerodynamic interaction between the turbine and the downstream baffle which accelerates the flow around the rotor and generates larger turning torque. The baffle generates a jet effect on the advancing bucket and accelerates the flow behind the bucket creating a large zone of negative pressure and thereby increases the driving torque. Furthermore, the upstream deflector (also called shield or curtain) produces a shield for the returning bucket of the turbine which diminishes the adverse effect associated with the returning bucket on the aerodynamic torque of the turbine. This remarkable improvement of turbine performance will encourage the future application of the Savonius wind turbine in small power applications of wind energy.

scholarly journals Analysis and Detection of Erosion in Wind Turbine Blades

2022 ◽  
Vol 27 (1) ◽  
pp. 5
Author(s):  
Josué Enríquez Zárate ◽  
María de los Ángeles Gómez López ◽  
Javier Alberto Carmona Troyo ◽  
Leonardo Trujillo
Keyword(s):  
Machine Learning ◽  
Wind Turbine ◽  
Power Efficiency ◽  
Dynamic Performance ◽  
Turbine Blades ◽  
Mechanical Damage ◽  
Leading Edge ◽  
Power Coefficient ◽  
Wind Turbine Blades ◽  
Material Loss

This paper studies erosion at the tip of wind turbine blades by considering aerodynamic analysis, modal analysis and predictive machine learning modeling. Erosion can be caused by several factors and can affect different parts of the blade, reducing its dynamic performance and useful life. The ability to detect and quantify erosion on a blade is an important predictive maintenance task for wind turbines that can have broad repercussions in terms of avoiding serious damage, improving power efficiency and reducing downtimes. This study considers both sides of the leading edge of the blade (top and bottom), evaluating the mechanical imbalance caused by the material loss that induces variations of the power coefficient resulting in a loss in efficiency. The QBlade software is used in our analysis and load calculations are preformed by using blade element momentum theory. Numerical results show the performance of a blade based on the relationship between mechanical damage and aerodynamic behavior, which are then validated on a physical model. Moreover, two machine learning (ML) problems are posed to automatically detect the location of erosion (top of the edge, bottom or both) and to determine erosion levels (from 8% to 18%) present in the blade. The first problem is solved using classification models, while the second is solved using ML regression, achieving accurate results. ML pipelines are automatically designed by using an AutoML system with little human intervention, achieving highly accurate results. This work makes several contributions by developing ML models to both detect the presence and location of erosion on a blade, estimating its level and applying AutoML for the first time in this domain.

scholarly journals Assessment of stress-blended eddy simulation model for accurate performance prediction of vertical axis wind turbine

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Taurista Perdana Syawitri ◽  
Yufeng Yao ◽  
Jun Yao ◽  
Budi Chandra
Keyword(s):  
Wind Turbine ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Content Type ◽  
Eddy Simulation

Purpose The aim of this paper is to assess the ability of a stress-blended eddy simulation (SBES) turbulence model to predict the performance of a three-straight-bladed vertical axis wind turbine (VAWT). The grid sensitivity study is conducted to evaluate the simulation accuracy. Design/methodology/approach The unsteady Reynolds-averaged Navier–Stokes equations are solved using the computational fluid dynamics (CFD) technique. Two types of grid topology around the blades, namely, O-grid (OG) and C-grid (CG) types, are considered for grid sensitivity studies. Findings With regard to the power coefficient (Cp), simulation results have shown significant improvements of predictions using compared to other turbulence models such as the k-e model. The Cp distributions predicted by applying the CG mesh are in good agreement with the experimental data than that by the OG mesh. Research limitations/implications The current study provides some new insights of the use of SBES turbulence model in VAWT CFD simulations. Practical implications The SBES turbulence model can significantly improve the numerical accuracy on predicting the VAWT performance at a lower tip speed ratio (TSR), which other turbulence models cannot achieve. Furthermore, it has less computational demand for the finer grid resolution used in the RANS-Large Eddy Simulation (LES) “transition” zone compared to other hybrid RANS-LES models. Originality/value To authors’ knowledge, this is the first attempt to apply SBES turbulence model to predict VAWT performance resulting for accurate CFD results. The better prediction can increase the credibility of computational evaluation of a new or an improved configuration of VAWT.

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