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Institute for Fluid Dynamics and Ship Theory (FDS)
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Institute for Fluid Dynamics and Ship Theory (FDS)
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FDS > Research > Completed Projects

Opimization of a Multi-Component Propulsor

Background

Fast ships require efficient propulsors with low sensitivity to cavitation within their operation range. Between the usual operational velocities of conventional propellers and waterjet propulsors there is a certain range, where Multi-Component Propulsors appear to be advantageous.

Figure 1: Developed Propulsor
Klick to enlarge
Figure 1: Developed Propulsor

The Multi-Component Propulsor regarded in this project consists of four components: rotor, hub, duct and stator, see figure 1. Aim of this project is the development of an optimisation based design-procedure for such a propulsor.

Approach

The duct is used to achieve a higher pressure level at the rotor-position in order to reduce the cavitation risk. Compared with the conventional propeller, the duct reduces the strength of the tip vortex and the stator helps to recover swirl energy from the rotor flow.

The geometry description as well as the interactions among the single components of the propulsor are quite complex. At the same time many design objectives have to be considered. First of all the propulsor has to fulfill thrust requirement at a certain number of revolutions. Moreover, the efficiency has to be maximized and the cavitation level to be minimized.

An appropriate technique for the design was developed which is able to consider all these demands, see figure 2. It uses a parameterized geometry description of the propulsor and automatic meshing tools. Furthermore, for the calculation of the velocity and pressure distribution at the different components of the propulsor two numerical codes are employed. The first one is an in-house developed potential flow method based on a first-order 3D-panel method. Figure 3 shows the pressure distribution calculated with potential flow theory  for one geometry of the propulsor during early optimisation stage. The ANSYS-CFX code is applied to calculate the viscous flow on the propulsor. The pressure distribution on a generated geometry of the propulsor during the final optimisation stage is shown in figure 4.

The design method is coupled with an evolutionary optimisation algorithm, which was developed at the Chair of Algorithm Engineering, Department of Computer Science of the Technical University of Dortmund.

Figure 2: Summary of design procedure
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Figure 2: Summary of design procedure

The optimised geometry of the propulsor was investigated experimentally at the Potsdam Model Basin (SVA Potsdam). Open water and cavitation tests were carried out. Figure 5 and 6 show the test model of the developed propulsor and its open water performance. The experimental data confirm that the applied numerical method provides reliable results and is suited to generate an optimized propulsor.

From the hydrodynamic point of view Multi-Component Propulsors may achieve a higher efficiency than conventional propellers at a certain speed range. According to model test results and viscous flow calculations for the full-scale case, the efficiency of an optimised geometry with good cavitation behavior can reach 73 %. In addition to that, the installation of the duct can be an advantage for ships working in extremely shallow water because the duct protects the propeller in grounding case. Another advantage of the employing of the duct is reduction of the hydro-acoustic impact on the environment.

Figure 3: Optimisation of the rotor and stator
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Figure 3: Optimisation of the rotor and stator
Figure 4: Pressure distribution on the propulsor
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Figure 4: Pressure distribution on the propulsor
Figure 5: Experimental investigation of the open water test behaviour
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Figure 5: Experimental investigation of the open water test behaviour
Figure 6: Open water tests
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Figure 6: Open water tests
Publications

Steden, M., Hundemer, J., Abdel-Maksoud, M.
Optimisation of a Linearjet
First International Symposium on Marine Propulsors, Trondheim, Norway, 2009

Steden, M., Hundemer, J., Müller, S.-B.,  Abdel-Maksoud, M.
Geometrische Parametrisierung und Untersuchung der Umströmung von aus Mehrkomponenten bestehenden Schiffsantrieben
102. Hauptversammlung der Schiffbautechnischen Gesellschaft, Berlin, 2007

Abdel-Maksoud, M., Steden, M., Hundemer, J.
Design of a Multi-Component Propulsor 
7th International Symposium on Cavitation, Ann Arbor, USA, 2009

Druckenbrod, M., Hundemer, J., Abdel-Maksoud, M., Steden, M.
Design of a Single- and Multi-Component Propulsors
COMPIT 2010, Gubbio, Italy, 2010

Personnel

Dipl.-Ing. Max Steden
Dipl.-Ing. Markus Druckenbrod
Dipl.-Ing. Jochen Hundemer
Prof. Dr.-Ing. Moustafa Abdel-Maksoud

Cooperation Partner

Prof. Dr. Günter Rudolph, Technical University of Dortmund, Department of Computer Science, Chair of Algorithm Engineering

Funding

German Research Foundation (DFG)

TU Hamburg
Institute for Fluid Dynamics and Ship Theory (M-8)
Am Schwarzenberg-Campus 4
21073 Hamburg
E-mail : fds@tuhh.de
Phone : +49 40 42878-6052
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