A ducted propeller is a propulsion device
consisting of a conventional open propeller surrounded by a duct
or nozzle. Ducted propellers find extensive applications in both
marine and aeronautical fields. The duct surrounding the
propeller may be used either to accelerate or to decelerate the
flow in the propeller plane. In marine applications the flow
accelerating duct is known as the "Kort Nozzle" and the
flow decelerating device is generally referred as the
The concept of surrounding the propeller by a
shroud is very old. Kort Nozzle ducted propellers have been
widely used in tugboats and trawelers where the propeller is
small and heavily loaded. The advantage of using a ducted
propeller for these vessels is that the flow is accelerated and
thus an improvement in propulsive efficiency is obtained In
addition the duct shares a fair proportion of the thrust and
thereby reduces the propeller loading. The flow accelerating
pump-jets find considerable applications for the propulsion of
submarines and torpedoes since the lower velocity in the
propeller plane helps to delay the cavitation induced noise. The
duct itself however will produce a negative thrust.
Vortex Element Method -
Iterative - V. Balabaskaran
Comparison of measured
and predicted duct thrusts
Aerodynamic studies of a Kort Nozzle Ducted
BIBILIOGRAPHY ON DUCTED PROPELLERS
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