Flow Simulation of a New Horizontal Axis Wind Turbine with Multiple Blades for Low Wind Speed

Abstract

AbstractIn this paper, a new design of a small horizontal-axis wind turbine is introduced. The design is based on the authors’ patent, which uses permanent magnets impeded into a shroud that holds the rotor blades. The generator coils are installed on a fixed diffuser that houses the rotor and acts as a wind concentrator. Therefore, the new design has no hub and is based on direct coupling for electricity generation. The main features of the design have been explored to highlight the advantages with a focus on how the new design can be integrated with the recent development of green buildings. The effect of increasing the number of blades and blade chord distribution on turbine performance has been investigated for the new turbine. Initial design and analysis were carried out using the Blade Element Momentum method and CFD simulations to identify the turbine performance and examine the flow characteristics. The results showed that further energy can be extracted from the turbine if the blade chord size increases at the shroud location and reduces at the turbine hub for a low Tip Speed Ratio TSR within the range of 1.5–3. Furthermore, having more blades can significantly increase the power coefficient and extend the range of operation with a high power coefficient. The number of blades, however, has to be optimised to achieve maximum power relative to the cost. Adding a diffuser and flanges surrounding the turbine can further increase the energy extracted from the wind at low speed.