Design and development of propellers for submarines are
in some ways different from propellers for surface
vessels. The most important demand is low acoustic
signature that has priority over propeller efficiency, and
the submarine propeller must be optimized with respect to
acoustics rather than efficiency. Moreover the operating
conditions of a submarine propeller are quite different.
These aspects are discussed as well as the weighing of the
various propeller parameters against the design
objectives.
The noise generated by the propeller can be characterized
as thrust noise due to the inhomogeneous wake field of
the submarine, trailing-edge noise and noise caused by
turbulence in the inflow.
The items discussed are demonstrated in a case study
where a propeller of the Kappel type was developed.
Three stages of the development are presented, including
a design of an 8-bladed propeller where the thrust
fluctuations as well as the thrust noise were significantly
reduced relative to a 7-bladed propeller. Results of
measurements are in good agreement with calculations.