Abstract: The present study is aimed at developing a methodology able to define, in a preliminary way but with sufficient accuracy, the waterjet performance using very few data, generally available at preliminary ship design stage. As known, naval architects traditionally use the waterjet graphical maps, provided by the waterjet manufacturer, in order to check if the available thrust is adequate to meet the resistance demands. The successful selection of a waterjet, however, requires an analysis of its performance across the vessel’s entire speed range. The paper presents a calculation methodology, based on a physical approach, able to predict the waterjet thrust curves and the corresponding cavitation limits in a wide range of operating conditions. The developed calculation methodology is useful when the pump maps are not available, because it’s enough to know only the nozzle area and to suppose the efficiency and the suction specific speed of the pump. These few parameters, together with the design pump speed and power, enable the ship designer to make reasonable thrust, power and cavitation predictions. The described procedure may be followed when the prime mover and the waterjet have been already selected and matched for design condition, in order to check that changes in operational condition lead to acceptable performance of the propulsion system. Moreover the described procedure may be followed to study the best possible combination for the ship-waterjet-engine system, through the optimisation of the selected design parameters. The procedure has been tested for the waterjet performance prediction of both pleasure craft and ro/ro passenger ferry, giving good results.

Waterjet performance prediction

ALTOSOLE, MARCO;BENVENUTO, GIOVANNI BATTISTA;FIGARI, MASSIMO
2003-01-01

Abstract

Abstract: The present study is aimed at developing a methodology able to define, in a preliminary way but with sufficient accuracy, the waterjet performance using very few data, generally available at preliminary ship design stage. As known, naval architects traditionally use the waterjet graphical maps, provided by the waterjet manufacturer, in order to check if the available thrust is adequate to meet the resistance demands. The successful selection of a waterjet, however, requires an analysis of its performance across the vessel’s entire speed range. The paper presents a calculation methodology, based on a physical approach, able to predict the waterjet thrust curves and the corresponding cavitation limits in a wide range of operating conditions. The developed calculation methodology is useful when the pump maps are not available, because it’s enough to know only the nozzle area and to suppose the efficiency and the suction specific speed of the pump. These few parameters, together with the design pump speed and power, enable the ship designer to make reasonable thrust, power and cavitation predictions. The described procedure may be followed when the prime mover and the waterjet have been already selected and matched for design condition, in order to check that changes in operational condition lead to acceptable performance of the propulsion system. Moreover the described procedure may be followed to study the best possible combination for the ship-waterjet-engine system, through the optimisation of the selected design parameters. The procedure has been tested for the waterjet performance prediction of both pleasure craft and ro/ro passenger ferry, giving good results.
2003
9788890048715
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/270003
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