scholarly journals Numerical Simulation of Unsteady Aerodynamic Performance of Novel Adaptive Airfoil for Vertical Axis Wind Turbine

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4106 ◽  
Author(s):  
Hui Tong ◽  
Jian Fang ◽  
Jinyang Guo ◽  
Kun Lin ◽  
Ying Wang

The aerodynamic performance of the blade determines the power and load characteristics of a wind turbine. In this paper, numerical research of the active deformation of an airfoil with equal thickness camber line was carried out, which shows the great potential of this active flow control method to improve the flow field. The NACA0012 is taken as the reference airfoil, and the inflow wind speed is 9 m/s, the chord length of the airfoil is 0.4 m, and the Reynolds number is 2.5 × 105. The influence factors, such as deformation amplitude and deformation frequency on the aerodynamic performance, were studied at different attack angles before and after stall. Studies have shown that: firstly, at different angles of attack, different deformation amplitudes and frequencies have great influence on the aerodynamic performance of the active deformed airfoil. The active deformation can improve the aerodynamic performance of the airfoil in different degrees in deep stall and light stall regions. Secondly, a suitable deformation amplitude and deformation frequency can improve the aerodynamic performance of airfoil stably and effectively in light stall, which occurs when the deformation amplitude equals to 0.02c and the deformation frequency is lower than 2 Hz, and the maximum lift-drag ratio can be increased by about 25%. Before stall, when the deformation frequency is 2 Hz and amplitude is 0.10c, the airfoil will have a negative drag coefficient in the process of deformation, and the airfoil will produce a thrust which is similar to the energy capture of the flapping foil. This is an unexpected discovery in our research.

2018 ◽  
Vol 53 ◽  
pp. 02004
Author(s):  
Qiuyun Mo ◽  
Jiabei Yin ◽  
Lin Chen ◽  
Weihao Liu ◽  
Li Jiang ◽  
...  

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.


2020 ◽  
Vol 23 (4) ◽  
pp. 771-780
Author(s):  
Anh Ngoc VU ◽  
Ngoc Son Pham

This study describes an effectively analytic methodology to investigate the aerodynamic performance of H vertical axis wind turbine (H-VAWT). An in-house code based on double multiple stream tube theory (DMST) coupled with dynamic stall and wake correction is implemented to estimate the power coefficient. Design optimization of airfoil shape is conducted to study the influences of the dynamic stall and turbulent wakes. Airfoil shape is universally investigated by using the Class/Shape function transformation method. The airfoil study shows that the upper curve tends to be less convex than the lower curve in order to extract more energy of the wind upstream and generate less drag of the blade downstream. The optimal results show that the power coefficient increases by 6.5% with the new airfoil shape.


2014 ◽  
Vol 529 ◽  
pp. 296-302 ◽  
Author(s):  
Wei Zuo ◽  
Shun Kang

The aerodynamic performance and the bypass flow field of a vertical axis wind turbine under self-starting are investigated using CFD simulations in this paper. The influence of pitch angle variations on the performance of the wind turbine during self-starting is presented. A two-dimensional model of the wind turbine with three blades is employed. A commercial software FlowVision is employed in this paper, which uses dynamic Cartesian grid. The SST turbulence model is used for turbulence modeling, which assumes the flow full turbulent. Based on the comparison between the computed time-dependent variations of the rotation speed with the experimental data, the time-dependent variations of the torque are presented. The characteristics of self-starting of the wind turbine are analyzed with the pitch angle of 0o、-2oand 2o. The influence of pitch angle variations on two-dimensional unsteady viscous flow field through velocity contours is discussed in detail.


Author(s):  
N. Cristobal Uzarraga-Rodriguez ◽  
A. Gallegos-Mun˜oz ◽  
J. Manuel Riesco A´vila

A numerical analysis of a rooftop vertical axis wind turbine (VAWT) for applications in urban area is presented. The numerical simulations were developed to study the flow field through the turbine rotor to analyze the aerodynamic performance characteristics of the device. Three different blade numbers of wind turbine are studied, 2, 3 and 4, respectively. Each one of the models was built in a 3D computational model. The effects generated in the performance of turbines by the numbers of blades are considered. A Sliding Mesh Model (SMM) capability was used to present the dimensionless form of coefficient power and coefficient moment of the wind turbine as a function of the wind velocity and the rotor rotational speed. The numerical study was developed in CFD using FLUENT®. The results show the aerodynamic performance for each configuration of wind turbine rotor. In the cases of Rooftop rotor the power coefficient increases as the blade number increases, while in the case of Savonius rotor the power coefficient decrease as the blades number increases.


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