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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.
Another example is the pump-jet, which is used for marine propulsion. Jet pumps are also used to circulate reactor coolant in several designs of boiling water nuclear reactor. In power generation, this phenomenon is used in steam jet air ejectors to maintain condenser vacuum by removing non-condensible gases from the condenser.
When the jet ski and the floating rider move with the water, the 20+ meter long hose can hang up on underwater obstructions. This can pull the rider, and potentially the jet ski under water as the hose becomes taut. Deaths have occurred in this manner and hydroflight in moving water is strongly recommended against.
Jet drives are inefficient in low speed vessels, but may have other advantages that make them suitable for a given application. Internal drive propulsion was originally designed by Sir William Hamilton (who invented the waterjet in 1954) for operation in the fast-flowing and shallow rivers of New Zealand, specifically to overcome the problem of ...
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 ...
Jet propulsion is produced by some reaction engines or animals when thrust is generated by a fast moving jet of fluid in accordance with Newton's laws of motion.It is most effective when the Reynolds number is high—that is, the object being propelled is relatively large and passing through a low-viscosity medium.
Even though these fluctuations in drag and mass can be ignored if the frequency of the jet-propulsion cycles is high enough, jet-propulsion is a relatively inefficient method of aquatic locomotion. All cephalopods can move by jet propulsion, but this is a very energy-consuming way to travel compared to the tail propulsion used by fish. [13]
A Flyboard rider stands on a board connected by a long hose to a watercraft. Water is forced under pressure to a pair of boots with jet nozzles underneath which provide thrust for the rider to fly up to 22 m (72 ft) in the air or to dive headlong through the water down as far as one is willing to go. [2] [failed verification]