axis wind turbines. The turbines in the paired configuration are closely spaced, at 1.2 and
1.3 rotor diameters shaft to shaft, and are counter-rotating. Two directions of rotation were
studied, one where the facing (inner) blades move along with the incoming flow, and one
where the facing blades move against the wind. The wind tunnel tests confirm a net increase
in the power coefficient of the paired configuration compared with twice the power coefficient …