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A ducted propeller, also known as a Kort nozzle, is a marine propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The Kort nozzle is ...
A marine thruster consists of a propeller or impeller which may be encased in some kind of tunnel or ducting that directs the flow of water to produce a resultant force intended to obtain movement in the desired direction or resist forces which would cause unwanted movement.
A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of both centrifugal and axial designs. The design also incorporates an intake to provide water to the pump and ...
Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats , most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller , or less frequently, in pump-jets , an ...
A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as water or air. [1] Propellers are used to pump fluid through a pipe or duct, or to create ...
The more recent podded drives consist of a propeller driven by a conventional electric motor into an azimuthable gondola under water, but they still incorporate a traditional hubcentric propeller. The blades of the rim-driven thruster, by contrast, are mounted on an outer ring rather than a central hub.
It is carried out to determine the open water characteristics of a propeller. A geometrically similar model is produced with the model-prototype correlation. The model propeller is attached to a propeller dynamometer fitted in an open water boat. The dynamometer measures the thrust and torque of the propeller.
This bubble completely encompasses the propeller that is in operation. With the differing characteristics of the seawater outside of the bubble and the air inside, a zone develops that has the ability to reduce the resonance frequency. [1] Due to this reduction, cavitation is less likely to occur during the operation of a marine propeller. [1]