Power Performance Improvement of 500W Vertical Axis Wind Turbine with Salient Design Parameters

This paper presents the performance characteristics of
Darrieus-type vertical axis wind turbine (VAWT) with NACA airfoil
blades. The performance of Darrieus-type VAWT can be
characterized by torque and power. There are various parameters
affecting the performance such as chord length, helical angle, pitch
angle and rotor diameter. To estimate the optimum shape of Darrieustype
wind turbine in accordance with various design parameters, we
examined aerodynamic characteristics and separated flow occurring
in the vicinity of blade, interaction between flow and blade, and
torque and power characteristics derived from it. For flow analysis,
flow variations were investigated based on the unsteady RANS
(Reynolds-averaged Navier-Stokes) equation. Sliding mesh algorithm
was employed in order to consider rotational effect of blade. To
obtain more realistic results we conducted experiment and numerical
analysis at the same time for three-dimensional shape. In addition,
several parameters (chord length, rotor diameter, pitch angle, and
helical angle) were considered to find out optimum shape design and
characteristics of interaction with ambient flow. Since the NACA
airfoil used in this study showed significant changes in magnitude of
lift and drag depending on an angle of attack, the rotor with low drag,
long cord length and short diameter shows high power coefficient in
low tip speed ratio (TSR) range. On the contrary, in high TSR range,
drag becomes high. Hence, the short-chord and long-diameter rotor
produces high power coefficient. When a pitch angle at which airfoil
directs toward inside equals to -2° and helical angle equals to 0°,
Darrieus-type VAWT generates maximum power.

Authors:

• Young-Tae Lee
• Hee-Chang Lim

Keywords:

• Darrieus wind turbine
• VAWT
• NACA airfoil
• performance.

References:

[1] IEA report (2012). World Energy Outlook 2012 – Renewable Energy
Outlook (Chapter 7). International Energy Agency.
[2] Gorelov, D. N. (2010). Energy characteristics of Darrieus rotor (review).
Thermophysics and Aeromechanics, 17-3, p301-308.
[3] Paraschivoiu, I., Trifu, O., Saeed, F. (2009). H-DarrieusWind Turbine
with Blade Pitch Control. International Journal of Rotating Machinery,
2009-505343, p1-7.
[4] Fujisawa, N., Shibuya, S. (2001). Observations of dynamic stall on
Darrieus wind turbine blades. Journal of Wind Engineering and
Industrial Aerodynamics, 89-2, p201-214.
[5] Ferreira, C.J.S. (2009). The near wake of the VAWT. 2D and 3D views
of the VAWT aerodynamics, Ph.D. Thesis, Delft University of
Technology.
[6] Maitre, T., Achard, J.L., Guitet, L., and Ploesteanu, C. (2005). Marine
turbine development: numerical and experimental investigations. Sci.
Bull. Timisoara Politechnic Univ., 50, p59-66.
[7] Howell, R., Qin, N., Edwards, J., Durrani,, N. (2010). Wind tunnel and
numerical study of a small vertical axis wind turbine. Renewable
Energy, 35, p412-422.