Nauwkeurigheidsoverwegingen en optimalisatie van de parameterkeuze bij gedwongen maneuvreerproeven met scheepsmodellen
Vantorre, M. (1989). Nauwkeurigheidsoverwegingen en optimalisatie van de parameterkeuze bij gedwongen maneuvreerproeven met scheepsmodellen. Teaching certificate Thesis. Rijksuniversiteit Gent. Faculteit der Toegepaste Wetenschappen: Gent. 2 vol. pp.
A thorough knowledge of ship manoeuvring behaviour, particularly in confined waters, is required for handling problems concerning the accessibility of harbours and waterways for specified Ship types in given circumstances by means of simulation studies.
For a scientific approach of this kind of problems, captive Ship model tests have to be carried out. A Ship model is forced by an external mechanism to undergo a prescribed trajectory in the horizontal plane; the measurement of forces acting on the model during these tests lead to the numerical value of a number of hydrodynamic manoeuvring coefficients occurring in the mathematical Simulation model.
This dissertation has a double purpose:
- the development of a general theory for determining the influence of divergences of the trajectory imposed to the ship model during captive model teats on the accuracy of the test results;
- application of this theory on a conventional program of captive model tests, finally resulting into an optimal choice of teat parameter. and, in addition, to a series of guide-lines for an optimal use of the test installation considered.
In chapter I, these purposes are situated in a general framework.
Chapters II and III give a review of the state-of-the-art on ship manoeuvring simulation. The mathematical models on which these simulations are based, are handled in chapter II; according to their concept, a division can be made into models based on a mathematical treatment of experimental results and formulations taking account of the physical background of the hydrodynamic forces acting on a ship hull. A review of the methods available for determining the numerical value of manoeuvring coefficients is given in chapter III; emphasis is put on experimental technique, particularly on captive ship model tests.
A general theory for determining the influence on results of captive model tests due to imperfections of the experimental techniques is developed in chapters IV and V. Chapter IV contains an analysis of the kinematics of a ship model during such tests: velocity and acceleration components are developed into a Taylor series about the prescribed values. The parameters of this series development are subdivided into control errors of the mechanism and geometrical inaccuracies of the experimental setup. The influence of these imperfections on the hydrodynamic forces acting on the ship model is dealt with in chapter V.
In chapters VI and VII, these general theoretical developments are worked out for a standard experimental program (chapter VI) and applied to a number of specific snips (chapter VII). An estimation is made of the accuracy of the experimentally determined numerical value of hydrodynamic manoeuvring coefficients. Discussion of the influence of the choice of the main experimental parameters leads to conclusions concerning optimal parameter choice.
The main conclusions are summarized in Chapter VIII.
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