Object and purpose of research. The study examines the procedures of self-propulsion tests performed on ship models with ducted propellers. The purpose is to analyze specific aspects of such experiments when these are conducted with and without dynamometer for thrust measurement on the propeller duct. Materials and methods. The list of measured quantities and methods of their display are worked out for the two alternative setups under consideration. Specific procedures for determination of hull/propeller interaction characteristics in these two cases are considered. Merits and limitations of the alternative methods are appraised. These issues are illustrated by test data obtained for one of the typical ship models. Main results. A hypothesis that ducted and open-water propellers operate in equivalent ship wake conditions is used to develop an approximate method for extrapolation of model test data obtained in self-propulsion tests with a ducted propeller system when duct thrust is not measured to the case when this duct thrust is measured and more comprehensive information on the physical conditions of propeller operation is obtained enabling a wide choice of calculation algorithms for propulsion performance estimations. It is found that hydrodynamic characteristics of the propeller duct depend on the extra radial angle of wake flow incidence on propeller, which limits the accuracy of the above extrapolation procedure. Conclusion. A procedure is suggested for extrapolation of model test data obtained in self-propulsion tests with ducted propellers when duct thrust is not measured to the case when this duct thrust is measured. It is shown that a radial wake flow angle behind hull should be estimated and taken into account for refining the methods for design of ducted propellers. The results of this study could be useful for researchers involved in ship propulsion estimates and experiments.
On propulsion test procedures for ship models with ducted propellers
2018
Article (Journal)
Electronic Resource
Unknown
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