My experiences with a torus demonstrated a shroud effect, increasing the wind speed on the propeller (or wind turbine), but also excessive drag. Indeed, tori are used as ballutes, which act like parachutes at very high speeds and in a rarefied atmosphere, and are aimed for planetary exploration, eliminating the problems caused by traditional parachutes under these conditions.
There are several types of ballutes. Some of these could perhaps advantageously replace parachutes or parasails: when inflated, the toroidal or lenticular ballutes can maintain their shape throughout the yo-yo cycle, presenting their front during the power reel-out phase, and their edge (to drastically reduce air resistance) during the recovery reel-in phase. They can be inflated with a gas lighter than air.
(PDF) Variable-Fidelity Hypersonic Aeroelastic Analysis of Thin-Film Ballutes for Aerocapture
Caption
Figure 1-8: Lenticular (left) and toroidal (right) ballutes are designed to reduce inflation gas mass [81, 82].
See also the figure 1-20 about the drag coefficient from the same document.
Another toroidal ballute:
(PDF) A DUAL-USE BALLUTE FOR ENTRY AND DESCENT DURING PLANETARY MISSIONS
Caption
Fig. 2. Toroidal Towed Ballute Configuration (Ball Aerospace Concept)
A ballute can also be like on the article below, being not as suitable in yo-yo mode.