scholarly journals Optimization on Airfoil of Vertical Axis Wind Turbine Based on CST Parameterization and NSGA-II Aigorithm

2016 ◽  
Author(s):  
Changping Liang ◽  
Deke Xi ◽  
Sen Zhang ◽  
Baofeng Chen ◽  
Xiangqian Wang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Tangential Force ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Force Coefficient ◽  
Nsga Ii ◽  
Drag Ratio

Optimizing the NACA0015 airfoil which is widely applied in small-scale vertical axis wind turbine to make it has a better aerodynamic performance. In the optimization process, using CST parameterization method to perturb the airfoil geometry, the thickness and camber of the airfoil are selected as the constraint, and the value of the maximum tangential force coefficient is chosen as the objective function, the genetic algorithm based on non-dominated sorting (NSGA-II)is selected as an optimization method, calculates the aerodynamic performance of the airfoil by applying the approach of combining XFOIL program and Viterna-Corrigan post-stall mode ,and establishes the optimizing process by the optimization software modefrontier for NACA0015 airfoil’s muti-point optimization, validate the airfoil’s performance with CFD finally. The result illustrates that, by comparing with the NACA0015 airfoil, the optimized airfoil’s lift to drag ratio is improved over a wide range of attack angles, the stall performance is more gentle. The maximum lift coefficient, the maximum lift-drag ratio and the maximum tangential force coefficient are increased by 7.5%,9 and 8.87%, respectively. The optimized airfoil has a wide variable condition performance, more suitable for the operating conditions of a vertical axis wind turbine. Finally, predict the rotor efficiency with optimized airfoil and NACA0015 airfoil for different tip speed ratios and different solidities with multiple streamtube model, the result shows the rotor with optimized airfoil has a higher efficiency.

scholarly journals Aerofoil optimization for improving the power performance of a vertical axis wind turbine using multiple streamtube model and genetic algorithm

2018 ◽  
Vol 5 (7) ◽  
pp. 180540 ◽  
Author(s):  
Changping Liang ◽  
Huaxing Li
Keyword(s):  
Wind Turbine ◽  
Tangential Force ◽  
Vertical Axis ◽  
Target Range ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Power Performance ◽  
Force Coefficient ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper reports on the optimization of the NACA0015 aerofoil for improving the power performance of a vertical axis wind turbine (VAWT). The target range of the chord Re is 3 × 10 5 –10 6 , the tip speed ratio (TSR) is 2–6 and the solidity is 0.2–0.6. This aerofoil is widely applied in small-scale VAWTs. In the optimization process, in which the class and shape function transformation parametrization method was used to perturb the aerofoil geometry, the thickness and camber of the aerofoil were selected as the constraints and the value of the maximum tangential force coefficient was chosen as the objective function. The aerodynamic performance of the aerofoil was calculated by combining the XFOIL program and Viterna–Corrigan post-stall model, while the aerofoil's performance was validated with computational fluid dynamic simulations. The results illustrated that, compared to an unoptimized NACA0015 aerofoil, the optimized aerofoil's lift to drag ratio was improved over a wide range of attack angles and the stall performance was gentler. The maximum lift coefficient, the maximum lift to drag ratio and the maximum tangential force coefficient were increased by 7.5%, 9% and 8.87%, respectively. Finally, this paper predicted the rotor efficiency with both the unoptimized and optimized NACA0015 aerofoils for different TSRs and different solidities using the multiple streamtube model. The results showed that the rotor with the optimized aerofoil has a higher efficiency.

scholarly journals Numerical evaluation of aerodynamic performances of vertical-axis wind turbine rotor with flow concentrator

2020 ◽  
Author(s):  
Jelena Svorcan ◽  
◽  
Ognjen Peković ◽  
Toni Ivanov ◽  
Miloš Vorkapić ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Power Coefficient ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Flow Simulations ◽  
Wind Speeds

With wind energy extraction constantly increasing, the interest in small-scale urban wind turbines is also expanding. Given that these machines often work in adverse operating conditions (Earth’s boundary layer, vortex trails of surrounding objects, small and changeable wind speeds), additional elements that locally augment wind velocity and facilitate turbine start may be installed. This paper investigates possible benefits of adding an optimized flow concentrator to a vertical-axis wind turbine (VAWT) rotor. Three-dimensional, unsteady, turbulent, incompressible flow simulations of both isolated rotor consisting of three straight blades and a rotor with flow concentrator have been performed in ANSYS FLUENT by finite volume method for several different operational regimes. This type of flow simulations is challenging since flow angles are high, numerous flow phenomena and instabilities are present and the interaction between the blades and detached vortices can be significant. The rotational motion of the blades is solved by the unsteady Sliding Mesh (SM) approach. Flow field is modeled by Unsteady Reynolds Averaged Navier-Stokes (URANS) equations with k-ω SST turbulence model used for closure. Both quantitative and qualitative examinations of the obtained numerical results are presented. In particular, the two computed power coefficient curves are compared and the advantages of installing a flow concentrator are accentuated.

scholarly journals Three-Dimensional CFD Simulation and Experimental Assessment of the Performance of a H-Shape Vertical-Axis Wind Turbine at Design and Off-Design Conditions

2019 ◽  
Vol 4 (3) ◽  
pp. 30 ◽  
Author(s):  
Nicoletta Franchina ◽  
Otman Kouaissah ◽  
Giacomo Persico ◽  
Marco Savini
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Computational Cost ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Numerical Predictions

The paper presents the results of a computational study on the aerodynamics and the performance of a small-scale Vertical-Axis Wind Turbine (VAWT) for distributed micro-generation. The complexity of VAWT aerodynamics, which are inherently unsteady and three-dimensional, makes high-fidelity flow models extremely demanding in terms of computational cost, limiting the analysis to mainly 2D or 2.5D Computational Fluid-Dynamics (CFD) approaches. This paper discusses how a proper setting of the computational model opens the way for carrying out fully 3D unsteady CFD simulations of a VAWT. Key aspects of the flow model and of the numerical solution are discussed, in view of limiting the computational cost while maintaining the reliability of the predictions. A set of operating conditions is considered, in terms of tip-speed-ratio (TSR), covering both peak efficiency condition as well as off-design operation. The fidelity of the numerical predictions is assessed via a systematic comparison with the experimental benchmark data available for this turbine, consisting of both performance and wake measurements carried out in the large-scale wind tunnel of the Politecnico di Milano. The analysis of the flow field on the equatorial plane allows highlighting its time-dependent evolution, with the aim of identifying both the periodic flow structures and the onset of dynamic stall. The full three-dimensional character of the computations allows investigating the aerodynamics of the struts and the evolution of the trailing vorticity at the tip of the blades, eventually resulting in periodic large-scale vortices.

scholarly journals Numerical Simulation of Aerodynamic Performance of Off-grid Small Vertical Axis Wind Turbine

2018 ◽  
Vol 53 ◽  
pp. 02004
Author(s):  
Qiuyun Mo ◽  
Jiabei Yin ◽  
Lin Chen ◽  
Weihao Liu ◽  
Li Jiang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Velocity Fields ◽  
Compact Model ◽  
Vertical Axis Wind Turbine ◽  
Wind Turbine Blades ◽  
Rotation Domain ◽  
Rng Turbulence Model

In this paper, a 2D off-grid small compact model of vertical axis wind turbine was established. The sliding grid technology, the RNG turbulence model and the Coupld algorithm was applied to simulate the unsteady value of the model's aerodynamic performance. Through the analysis on the flow field at difference moments, the rules about velocity fields, vortices distributions and the wind turbine's total torque were obtained. The results show that: the speed around wind turbine blades have obvious gradient, and the velocity distribution at different times show large differences in the computional domain. In the rotating domain vorticity is large. With away from the rotation domain, vorticity reduced quickly. In the process of rotating for vertical axis wind turbine, the wind turbine's total torque showed alternating positive and negative changes.

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