Experimental and Numerical Investigations for Combined Blade Vertical Axis Wind Turbine

Abstract

In this paper, experimental and numerical investigations were carried out to evaluate the drag force of a combined frame with movable vanes. For this purpose, the combined frame model was developed from a flat plate with three movable vanes and one Darrieus straight bladed NACA0012. A straight-bladed Darrieus NACA0012 airfoil is attached at the tip of the model structure. The design increases the starting and total torque of the model on the side, which rotates to wind direction, hence increasing the drag coefficient  and reduces the negative torque on the other side of the frame that rotates opposite to the wind. Combined frame in experimental work is tested in the subsonic wind tunnel to analyze the performance parameters like drag force   and drag coefficient . The frame is tested under different wind speed ranging from 4 m/s to 28 m/s, test results show the reliable and efficient performance. The results indicated that the maximum drag force  for the combine frame is 6 N at experimental work and 5.649 at numerical simulation under the same condition (wind speed V=28 m/s and azimuth angle θ = 90°). Computational Fluid Dynamic software (CFD) ANSYS FLUENT is used in this simulation which is carried out for the combined frame to investigate the drag force and drag coefficient, The finite volume method with Shear Stress Transport (STT), k-  turbulence model is used, the predicted results show that the flow through the combined frame at the negative side when all the vanes are freely open. The static pressure drops across the combined frame when the combined frame rotates to the negative side and the resistance of the combined frame to the flow decreased. This case helps to increase turbine angular velocity  and this leads to an increase in the power coefficient of the turbine.