Showing 4 results for Vertical Axis Wind Turbine
Ali Esfandiari, Majid Bazargan,
Volume 14, Issue 2 (5-2014)
Abstract
Due to growth of energy consumption and depletion of fossil fuels sources, power generation of renewable energy sources such as wind energy has become one of the main interests of researchers. Among different types of wind turbines used for extracting electric power from wind flow, vertical axis wind turbines can be implemented in urban areas and in proximity of energy consumers because of their independence of wind direction, low sensitivity to wind turbulence and lower noise production. In this paper a straight-bladed vertical axis wind turbine has been simulated 3 dimensionally by use of a commercial CFD code. The numerical results have been validated against available experimental data. To improve the performance of the turbine, the effects of blade mount point offset and preset pitch have been investigated. The results show that appropriate blade offset and preset pitch for this case study leads to a 60 and 65 percent increase in the maximum performance coefficient respectively.
Mahdi Zamani, Mohammad Javad Maghrebi,
Volume 15, Issue 11 (1-2016)
Abstract
In this study, the self-starting of a Darrieus vertical axis wind turbines (VAWT) is enhanced using a J-Shaped airfoil profile. The paper investigated the performance of VAWT with the J-shaped blades. Since the J-shaped blades utilize the lift and drag forces simultaneously, the turbine performance at low tip speed ratios (TSRs) enhances. Thus, it is expected that using these blades improves the starting torque and output power. The main goal in this study is to find an optimum J-shaped profile acquiring the best performance of wind turbine. For this purpose, a 3kW J-Shaped straight-bladed Darrieus type VAWT is investigated numerically using OpenFOAM computational fluid dynamic package. It employs the finite volume method to solve the Navier-Stokes equations. The J-Shaped profile is designed by means of eliminating a fraction of pressure side of Du 06-W-200 airfoil. The results indicate that the performance of turbine is optimized for J-shaped profile which eliminates the pressure side of airfoil from the maximum thickness toward the trailing edge. Moreover, employing this J-Shaped profile, the wind turbine performance is intensified TSRs and self-starting of turbine is improved.
Maryam Amiri, Mohsen Kahrom, Ali Reza Teymourtash,
Volume 17, Issue 5 (7-2017)
Abstract
One of the disadvantages of drag driven vertical axis wind turbines, is low aerodynamic performance of the turbine which is mainly due to adverse torque of the returning blade. A recently introduced design suggests using opening/closing blades for the rotor to eliminate the negative torque of the returning blade. In this study, the aerodynamic performance of the newly proposed turbine has been investigated experimentally and numerically. The experimental measurements are performed in a subsonic open-jet type wind tunnel facility. However, the numerical simulations are performed using the Ansys-Fluent commercial software, using the Multiple Reference Frame model (MRF). The effects of the number of blades (3, 4 and 6-bladed), end plates and turbulence intensity on the torque and power coefficients are examined in details, in several Reynolds numbers. Results show that the new rotor has no negative torque in one complete revolution and the 3-bladed rotor has the best aerodynamic performance, in a manner that, it reaches a maximum power coefficient of 0.21 at TSR=0.5. Although increasing the number of blades decreases the output torque oscillations, it also decreases the average power coefficient of the rotor. Results also show that, Reynolds number does not have significant effects on the average power coefficients of the rotors, in the studied range of Reynolds numbers, 7.7×104 ≤ Re ≤ 1.2×105.
A. Taban, A. Jalali, M. Zamani,
Volume 20, Issue 7 (6-2020)
Abstract
Humans are always looking for ways to produce cheap and permanent electricity. One of these ways is to use wind turbines. The vertical axis wind turbines are less sensitive due to the problem of the setup and low efficiency compared to the horizontal axis turbines. One way to improve the performance of VAWTs is to change the angle of attack of the wind turbine blade. In this study, the computational fluid dynamics method is used to solve the finite volume flow equations. Different angles of attack range from -12 to +10 degrees and wind speeds of 10m/s and density of 1.225kg/m3 and constant dynamic viscosity of 1.825psi were used. The calculations showed that by increasing the angle of attack of the blade to +10 degrees Cp and Torque decreased, by decreasing angle of attack of the blade to -4 degree, Cp and Torque increased, but by more decreasing AOA of -8 to -12 degrees Cp and torque decreased.
