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Kort nozzle The towboat Dolphin I in a floating drydock on the Mississippi River in Algiers, Louisiana. 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 ...
Beyond this point the nozzle diameter becomes the biggest diameter and starts to incur increasing drag. Nozzles are thus limited to the installation size and the loss in thrust incurred is a trade off with other considerations such as lower drag, less weight. Examples are the F-16 at Mach 2.0 [21] and the XB-70 at Mach 3.0. [22]
The word is commonly used in the marine vernacular, and implies a mechanical assembly that is more complicated than a propeller. The Kort nozzle, pump-jet and rim-driven thruster are examples. An example propulsor is shown in the accompanying picture. It has a shroud which cuts down on blade-tip cavitation and radiated noise.
Schematic diagram showing the operation of a turboprop engine Propulsive efficiency for different engine types and Mach numbers. Exhaust thrust in a turboprop is sacrificed in favor of shaft power, which is obtained by extracting additional power (beyond that necessary to drive the compressor) from turbine expansion.
Ludwig Kort (1888 - 1958 [1]) was a German fluid dynamicist known for developing the ducted propeller, or Kort nozzle. In an attempt to reduce canal erosion, Kort discovered that directing the wake of a propeller through a short, stationary nozzle also increased thrust. [2] He submitted a U.S. patent for this technique, which was awarded in ...
English inventor Francis Ronalds described what he called a propelling rudder in 1859 that combined the propulsion and steering mechanisms of a boat in a single apparatus. . The propeller was placed in a frame having an outer profile similar to a rudder and attached to a vertical shaft that allowed the device to rotate in plane while spin was transmitted to the propell
Figure 1: A de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow Density flow in a nozzle. A rocket engine nozzle is a propelling nozzle (usually of the de Laval type) used in a rocket engine to expand and accelerate combustion products to high supersonic velocities.
In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller. [1] When used in vertical takeoff and landing applications it is also known as a shrouded rotor. [2]