AbstractsEngineering

Modernizing Thruster Design: A Numerical Investigation of a Ducted Azimuthing Thruster in Oblique Flow:

by S. Pavlioglou




Institution: Delft University of Technology
Department:
Year: 2015
Keywords: azimuthing; CFD; oblique; thruster; steering; bearing reactions; turbulence; computational fluid dynamics; rules of thumb; propulsion
Record ID: 1258430
Full text PDF: http://resolver.tudelft.nl/uuid:2c7f8595-243f-4c42-9c26-187bf4976bce


Abstract

The rudder-propeller, as the azimuthing thruster was originally called, can be rotated 360 degrees and is capable of delivering full propulsive power in any direction. The azimuthing thruster makes use of a mechanical transmission in order to deliver the power from the prime mover to the propeller. The good maneuverability and the absence of a need for a rudder of such a propulsion unit are counteracted by lack of detailed knowledge for this unconventional propulsion device. The field of uncertainty lies primarily in the very nature of the thruster, namely the fact that it is capable of rotating while operating. The oblique angle of the inflow to the thruster can be the source of a series of complex phenomena, not all of which have been systematically monitored and analyzed. The goal of the present study is: to investigate in depth the hydrodynamic characteristics of a ducted azimuthing thruster and to showcase the potential impact of findings on the current detailed design approach. By means of CFD numerical software StarCCM+, the thruster was modelled in a way which would allow the simulation of oblique inflow cases. A realization of a series of operating conditions for various advance velocities, RPM and steering positions of the thruster was followed by a thorough explanation of the observed physical phenomena. The information acquired by the numerical simulations was then compared with characteristic rules of thumb that represent the prevailing method of design nowadays. Finally, a few selected cases were used as the basis for the realization of a force propagation analysis with the purpose of comparing the bearing reaction forces of the propeller shaft to the respective values that arise based on simplistic rule of thumb calculations. Through the course of this project, valuable information was acquired for the behavior of the thruster unit in oblique inflow. The majority of the cases have been found to be in accordance with the imposed rules of thumb. However, a few cases demonstrated divergence from the predicted values in very large inflow angles.