Toroidal propellers, also known as ducted propellers, are a type of propeller that are enclosed within a toroidal or circular duct. The purpose of the duct is to increase the efficiency of the propeller by reducing turbulence and drag, as well as to provide a measure of safety for people and objects that might come into contact with the rotating blades.
In general, toroidal propellers are used in applications where a high thrust-to-power ratio is required, such as in marine propulsion systems, underwater propulsion systems, and some types of wind turbines. They can also be used in small unmanned aerial vehicles (UAVs) where the reduced noise level is an advantage.
One of the key benefits of toroidal propellers is that they can generate more thrust than an equivalent open propeller of the same size, due to the increased pressure in the duct. This increased pressure also makes the propeller more efficient, as less energy is lost to turbulence and drag. Additionally, the ducted design helps to contain the propeller wash and reduce noise emissions.
There are some drawbacks to using toroidal propellers, however. For example, they can be more complex to design and manufacture than open propellers, and they can also be heavier and more bulky. Additionally, the duct may create additional drag, which can reduce the overall efficiency of the propulsion system.
Overall, toroidal propellers are a useful technology for a wide range of applications, providing increased efficiency and reduced noise compared to open propellers. Whether they are the best choice for a particular application will depend on a number of factors, including the size and power requirements of the propulsion system, as well as the desired thrust-to-power ratio and noise levels.
