A toroidal propeller or ring-shaped propeller is a type of propellerthat is ring-shaped. Toroid propellers are significantly quieter (especially at audible frequences, which are between 20 Hz to 20 kHz), and are claimed to be more efficient than traditional propellers both in air and water. It is promising for reduced noise pollution through quieteraviation- and maritime transport.
The torus propeller is said to have been invented in the early 1900s, around 120 years ago.[citation needed]
In 2017, the design was brought up to date again when Massachusetts Institute of Technology (MiT) applied for a patent for the toroid propeller, and in 2020 the application was granted.[1] In 2022, Lincoln Laboratory was awarded the R&D 100 Award for making the torus propeller available.[2][3]
Sharrow Marine has developed propellers for marine use in boats, and claims that the benefits of less fuel consumption (higher efficiency) and less noise are even greater in water.[4]
The design ditributes vortices generated by the propeller along the entire shape of the propeller, which means that noise is distributed and dampened more quickly.[5][6] The propeller design has similarities with the closed wing which is annularly shaped, and therefore distributes the vortices generated along the entire shape instead of just at the tip.
Drone propellers made according to this principle have been tested which emit a sound frequency between 1-5 Hz,[7] which is outside the audible spectrum for humans.
((cite journal)): Cite journal requires |journal= (help)