The present disclosure relates to a fluid turbine including a rotor and one or more ringed airfoil segments in fluid communication with a wake of the rotor. Each of the ringed airfoil segments includes a leading edge positioned co-planar with or downstream of the rotor plane as measured along the central axis. The ringed airfoil segments may include associated mixing elements. The fluid turbine may include a second ringed airfoil downstream of the one or more ringed airfoil segments.