HYDRODYNAMIC PROPULSION AND ITS OPTIMIZATION ANALYTIC THEORY
Hydrodynamic propulsion has been of major interest ever since craft took
to the water. In the course of time, many attempts have been made to
invent, develop, or to improve hydrodynamic propulsion devices.
Remarkable achievements in this field were made essentially by
experienced individuals, who were in need of reliable propulsion units
such as paddle wheels, sculling devices, screw propellers, and of
course, sails. The problem of minimizing the amount of input energy for
a prescribed effective output was first investigated seriously at the
beginning of this century. In 1919, BETZ presented a paper on air-screw
propellers with minimum consumption of energy which could be applied to
ship-screw propellers also. Next, attempts were made to optimize
hydrodynamic propulsion units. Ensuing investigations concerned the
optimization of the hydrodynamic system: ship-propeller. The first
simple theory of ship propulsion which was presented considered more or
less only thrust augmentation, wake processing and modification of
propeller characteristics when operating behind the ships hull. This
theory has been little improved meanwhile and is still useful,
particularly with regard to practical ship design and for evaluating
results of ship model tests. However, this theory is not adequate for
optimization procedures necessary for high-technology propulsion,
particularly for ship propellers utilizing propulsion improving devices
such as tip end plates or tip fins at the propeller blades, spoilers in
front of the propeller, asymmetrical stern etc.
