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International Journal of Rotating Machinery
Volume 2012, Article ID 474785, 11 pages
http://dx.doi.org/10.1155/2012/474785
Research Article

Open-Water Thrust and Torque Predictions of a Ducted Propeller System with a Panel Method

1Department of Mechanical Engineering, Marine Environment and Technology Center (MARETEC), Instituto Superior Técnico (IST), Technical University of Lisbon, 1049-001 Lisbon, Portugal
2Maritime Research Institute Netherlands (MARIN), Wageningen, The Netherlands

Received 2 December 2011; Accepted 8 March 2012

Academic Editor: Moustafa Abdel-Maksoud

Copyright © 2012 J. Baltazar 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

This paper discusses several modelling aspects that are important for the performance predictions of a ducted propulsor with a low-order Panel Method. The aspects discussed are the alignment of the wake geometry, the influence of the duct boundary layer on the wake pitch, and the influence of a transpiration velocity through the gap. The analysis is carried out for propeller Ka4-70 operating without and inside a modified duct 19A, in which the rounded trailing edge is replaced by a sharp trailing edge. Experimental data for the thrust and torque are used to validate the numerical results. The pitch of the tip vortex is found to have a strong influence on the propeller and duct loads. A good agreement with the measurements is achieved when the wake alignment is corrected for the presence of the duct boundary layer.