Abstract
The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth angles of power generation capabilities. This paper studies the effects of the helix angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different helix angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the helix angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.
Highlights
Unhindered access to electric power is one of the most important factors ensuring the dynamic development of the countries and civilisations
It is seen that the straight blade Vertical axis wind turbines (VAWT) showcases its best performance in a lower tip speed ratio (TSR) range (2.7–3), but when a helix angle is introduced, the performance curve shows a shift in the peak, maintaining a similar overall trend of the curve
For helix angles 90◦ and 120◦, the performance is comparable with a straight blade turbine, but the performance is peaking at a higher TSR
Summary
Unhindered access to electric power is one of the most important factors ensuring the dynamic development of the countries and civilisations. Due to ecological and economic issues, many countries are introducing new regulations to cut down the utilisation of fossil fuels and emission of CO2 [1,2,3]. According to these regulations, most of the states have committed to increase their fraction of the generation of the renewable sources of energy of the total installed electric power generation capacity. The main disadvantage of using wind energy is its high sensitivity to the forecast conditions [4,5].
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