Abstract: In order to expand the application scope of horizontal-axis wind turbines, the aerodynamic performance of the two new horizontal-axis spiral wind turbines and their ducted types are investigated by three-dimensional computational fluid dynamics simulation. The results show that the variable-angle spiral wind turbine has a higher power coefficient (C_P) than the constant-angle spiral wind turbine in the lower tip-speed ratio (TSR) range. Moreover, the variable-angle spiral wind turbine has a lower thrust coefficient (C_T) across the whole TSR range compared to the constant-angle spiral wind turbine, with the difference in C_T between the two spiral wind turbines increases as TSR grows. The high-pressure areas of the two spiral wind turbines mainly concentrate at the front of the hub, the windward side of first-order, and second-order rotating blades.Conversely, the low-pressure areas mainly gather at the leeward side of third-order rotating blades and the hub’s rear end. The wake recovery of the variable angle spiral wind turbine is faster than that of the fixed angle spiral wind turbine due to the blockage degree of the front rotating blade is relatively small. In addition, the duct can significantly improve C_P and C_T of the two spiral wind turbines, widening the TSR range of C_P. The results reveal the aerodynamic performance of horizontal-axis spiral wind turbines, providing valuable references for the optimizing the design and promoting the application of this type of wind turbines.

Key words: wind energy, horizontal-axis spiral wind turbine, duct, aerodynamic performance, computational fluid dynamics