Propulsor
From Wikipedia, the free encyclopedia
A propulsor is a mechanical device that gives propulsion.
The word is commonly used in the marine vernacular, and implies a mechanical assembly that is more complicated than a propeller. The Kort nozzle and Pump-jet are examples.
A propulsor, as can be seen in the accompanying picture has a shroud, which cuts down on blade-tip cavitation and radiated noise. It also has a rotor element and a stator. The number of blades in the rotor & stator will always be odd-numbered, and will be different prime numbers to avoid standing waves. The blades in the rotor and stator will be angled to contra-rotate, thus avoiding the creation of angular torque.
