Improving the efficiency of Darrieus turbines through a gear-like turbine layout

In recent years, there were some studies on arrays of multiple Darrieus turbines that have shown the potential benefits of interaction between Darrieus turbines in an array configuration to improve performance compared to isolated turbines. However, all these studies were for two separate turbines, whose spacing cannot be smaller than the diameter. This paper uses the 2D CFD method to propose a Darrieus turbine layout similar to the gear meshing principle, where the adjacent turbine gap can be smaller than the diameter. A comparative analysis of the new layout with 2 rotational directions, 5 turbine gaps and different numbers of turbines in the multi-turbine layout form is carried out. It is found that in the two-turbine layout, there can be an efficiency improvement of 28.92%; while in the multi-turbine layout, its efficiency gradually increases with the number of turbines at TSR = 3.0 and finally stabilizes at a Cp-corr of 0.588.