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International Journal of Rotating Machinery
Volume 2012, Article ID 321306, 12 pages
http://dx.doi.org/10.1155/2012/321306
Research Article

Dimensionless Numerical Approaches for the Performance Prediction of Marine Waterjet Propulsion Units

1Department of Naval Architecture and Electrical Engineering, University of Genoa, 16145 Genoa, Italy
2Department of Thermal Machines, Energy and Transport Systems, University of Genoa, 16145 Genoa, Italy

Received 2 December 2011; Revised 23 April 2012; Accepted 12 May 2012

Academic Editor: Yin Lu Julic Young

Copyright © 2012 Marco Altosole et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

One of the key issues at early design stage of a high-speed craft is the selection and the performance prediction of the propulsion system because at this stage only few information about the vessel are available. The objective of this work is precisely to provide the designer, in the case of waterjet propelled craft, with a simple and reliable calculation tool, able to predict the waterjet working points in design and off-design conditions, allowing to investigate several propulsive options during the ship design process. In the paper two original dimensionless numerical procedures, one referred to jet units for naval applications and the other more suitable for planing boats, are presented. The first procedure is based on a generalized performance map for mixed flow pumps, derived from the analysis of several waterjet pumps by applying similitude principles of the hydraulic machines. The second approach, validated by some comparisons with current waterjet installations, is based on a complete physical approach, from which a set of non-dimensional waterjet characteristics has been drawn by the authors. The presented application examples show the validity and the degree of accuracy of the proposed methodologies for the performance evaluation of waterjet propulsion systems.