By means of the axiomatic system the naive concepts of propulsion theory are implicitly defined and expressed in terms of measurable quantities of the propeller inflow under service conditions, thus providing for an adequate evaluation of the propulsion factors under all circumstances. After short discussion of the most important implications of the theory, as an example of its range of applicability the scale effects are discussed, which have to be accounted for in power predictions based on model tests.
Immediate plausibility and the agreement with the usual jargon indicate - far from being philosophical virtues - that not much progress has been achieved or will be achieved. Paul Feyerabend: Against method. 1965. ABSTRACT Design, testing and evaluation of vehicles propelled in flu- ids, ship hull-propeller configurations in particular, are traditionally based on the naive conception of propulsors producing thrust to overcome the resistance of the bodies to be propelled. While for more or less slender hulls this conception has been more or less sufficient for more than a century this conception is no longer adequate for more or less advanced hull adapted or even hull integrated pro- pulsor configurations. In view of the well known deficiencies of the traditional approach even in case of traditional hull propeller con- figurations the author has developed a rational theory of propulsion, essentially coherent, axiomatic systems of conventions for the rational resolution of conflicts, typi- cally between ship owners and ship yards. These abstract theories, clearly (to be) distinguished from their operational interpretations in terms of experimental, physical or numerical, and theoretical hydromechanics, have permitted to solve a number of fundamental prob- lems of propulsion theory, which could not possibly have been solved following the traditional approach. During the past fifty years of development the rational ap- proach has paradigmatically been demonstrated in a num- ber of different problems to offer dramatic conceptual and commercial advantages. A prominent example is the iden- tification of scale effects in wake and thrust deduction fractions at the METEOR under service conditions from quasi-steady tests even in heavy weather taking only 30
Main dimensions in terms of diameters and performance data in terms of open water charts do not permit readily to assess the merits of given ducted propulsors. Pre-requisite for this purpose are explicit 'curves' of flow cross-sections and of the equivalent ideal and the hydraulic efficiencies of the propulsors and, maybe, additional detailed evaluations of rotor and stator performances. The sample evaluations provided, conveniently arranged in reverse order, may be acceptable as first steps towards a rational standard of presentation to be developed and agreed upon by the parties concerned.
A stream function approach proposed earlier for the of ideal propellers in the open water condition in an ideal fluid is extended to the design of optimal, wake adapted, ducted propellers for deeply submerged bodies of revolution in real fluids. Based on an axiomatic theory of hull-propeller interaction, a condition for optimum propulsion is derived and subsequently the principal parameters of the propeller conceived as a pump stage are obtained in a preliminary design procedure. The flow field computations necessary to determine the distributions of velocity components and static pressure at the inlet and outlet of rotor and stator are outlined. Based on the distributions of the velocities and pressure the total thrust and the rotor thrust can be obtained by integration and the blades of rotor and stator can be designed. A numerical example and results of extensive parametric studies are given in the paper.
The objective of the investigation described was to determine the transverse stability of high speed ships in smooth waters. A problem, from the design engineer's point of view, is to ensure this stability in the early phases of the design process. For the solution of this problem, a procedure that is based on the measurement of stability derivatives of hulls with appendages (but without propellers) has been developed and tested.
The full scale measurements reported are part of a project to determine the scale effects of a SES with reference to corresponding model tests. The paper describes the details of the shaft calibration, of the measurements on board the CORSAIR, of the first results of their evaluation, and of the identification of the propulsion parameters based on data observed at periodic quasi-steady changes of the rates of shaft revolutions. Corresponding model tests were performed and preliminary evaluations confirmed the observations made during the full scale tests.
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