Ship Propeller

Ship Propeller

 

any device that converts energy into useful work for driving a ship. Some propelling devices, such as sails, use external sources of energy, for example, wind or water currents; others are put into operation by human energy, for example, oars and poles, or by marine engines. Indirect propelling devices include screw propellers and paddle wheels, rotary-blade propellers, and airscrews. Direct propelling devices include water-jet propellers and air-breathing jet engines.

All ship propellers have the common property that the driving force, or thrust, they produce is equal to the resistance encountered by the ship when it travels through the water along a straight line at a constant speed. In the case of tugboats, the thrust is equal to the resistance encountered by the tugboat itself and by the object being towed. The efficiency of a ship propeller for a particular combination of hull and rudder is specified by the propulsive coefficient—the ratio of the towing power of the ship to the power delivered at the propeller.

The choice of a ship propeller is dictated by the function of the ship. For example, ships that work in shallow water or obstructed channels use water-jet propellers. Ships with greater maneuverability use rotary-blade propellers.

E. G. LOGVINOVICH [25–140–1 ]

References in periodicals archive ?
At Panatag they pulverize surrounding corals with ship propeller blades to get at giant clams.
Summary: The whale most likely hit a ship propeller.
The rectangular chandeliers that hang from the ceiling encase rows of vintage Edison bulbs, and one of the tables is fashioned from a huge ship propeller. class="Magazinebodytextspan xml:lang="EN-GBA mustard couch and a deep red carpet add splashes of colour against the grey stone floor.
The worlds first certificated 3D-printed ship propeller, the WAAMpeller, was produced in the centre last year.
The Sun Herald reports Rolls-Royce North America is closing the foundry at its Pascagoula, Miss., ship propeller manufacturing plant and expects to lose 24 skilled workers of the 47 employees there.
Rieck, "Investigation of pressure fluctuations caused by turbulent and cavitating flow around a P1356 ship propeller," in Proceedings of the NAFEMS Seminar: Simulation komplexer Stromungsvorgange (CFD), 2008.
[v.sub.p] - ship propeller screw speed, could be calculated as follows [2] (EAU 2012):
Damen collaborates to develop 3D printed ship propeller
[3] Andersen, JP 1994, Hydrodynamic of Ship Propeller, Elsevier, Cambridge.
Ship propeller design theory did not apply directly to air screws.
BRITAIN'S last remaining ship propeller maker has been saved after a deal with a Chinese manufacturer.
Its Delta Stream technology takes the concept of wind turbine and ship propeller systems deep beneath the ocean, each generating 1.2 megawatt of energy.