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Experimental and Theoretical NANOTECHNOLOGY (ETN) is a multidisciplinary peer-reviewed international journal published three issues a year. It includes specialized research papers, short communications, reviews and selected conference papers in special issues on the characterization, synthesis, processing, structure and properties of different principles and applications of NANOTECHNOLOGY; with focus on advantageous achievements and applications for the specialists in engineering, chemistry, physics and materials science.
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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 𝐶𝑑 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 force𝐹𝑑 and drag coefficient 𝐶𝑑. 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 𝐹𝑑 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-𝜔 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 (𝜔) and this leads to an increase in the power coefficient of the turbine.
Keywords: Drag Force; Movable Vanes; Combined; Straight Bladed.