Design and Performance Evaluation of a Helical Vertical-Axis Wind Turbine for Low-Wind-Speed Renewable Energy Applications

The major challenge is the straight-bladed design, which has a high wind load due to torque pulsations and a poor self-starting characteristic in windy cities, despite having omni-directional operation and low cut-in speed, vertical-axis wind turbines (VAWTs) do have. The objectives of this research are to optimize the helical VAWT for wind power generation in low wind speed applications to achieve functions such as self-starting, smooth torque output and sustainability of the machine in terms of structural, low-cost material. The design features a helical rotor that is restricted to an aspect ratio of 1.5 to 2.0 and mild steel support strips with Amazon uPVC Blades (ASTM D1785-94). The methodology comprised of five wind speeds (2.80–8.50 m/s) of controlled wind-tunnel testing and static structural and modal analyses using ANSYS. The tip speed ratio (\(\:λ\:=ω\:R/U\)), electrical power coefficient (\(\:{C}P,elec\) = \(\:{{P}elec}{{P}wind}\)) and available wind power (\(\:{P}wind=1/2ρ\:A{U}³\)) governed aerodynamic performance. The results indicated that the rotor has a cut-in wind speed of 2.80 m/s, where the rotor output power at \(\:{P}elec\) is 3.12 W with λ value of 0.83. The rotor achieved a maximum rotor revolving speed N = 300 RPM corresponding to the maximum tested wind speed U = 8.50 m/s, and the wind power \(\:{P}wind\) increased from 8.47 W to 120.5 W. The structural parameters obtained by structural analysis are factor of safety FOS = 3.6, maximum von Mises stress \(\:{σ\:}ₘₐₓ\)= 12.4 MPa, maximum deformation \(\:{δ\:}ₘₐₓ\)= 3.8 mm, and the natural frequencies are f₁ = 8.7 Hz, f₂ = 14.2 Hz and f₃ = 23.5 Hz respectively. The study concludes that the helical uPVC VAWT is technically feasible for low wind facility micro-generation size plants, however, scale up is necessary in the domestic application level.