effects are more important. For more complex propeller shapes (high skew) a better result is obtained with RANS than with a BEM. Additionally, viscosity related flow features such as separation and the development of vortices can only be captured and analysed using a viscous- flow approach.
• For the ducted propeller a comparison between model and full scale computations was made. Propeller thrust, duct thrust, propeller torque and total open-water efficiency were all larger at full scale. Te gains in efficiency vary between 4 and 10% for different loading conditions.
Te wealth of information obtained from viscous CFD calculations allows for a more detailed analysis of propeller design than in the past. Tis, in combination with the possibility to do both model and full scale computations, provides the propeller designer with knowledge that can lead to
further gains in propulsive efficiency. Te logical following topic is the analysis of a propeller operating behind a ship, both in model and full-scale. Marin is currently enhancing the CFD tools for taking the complete ship-propulsion system into account. NA
References 1. SALVATORE, F., STRECKWALL, H., and VAN TERWISGA, T., ‘Propeller Cavitation Modelling by CFD – Results from the VIRTUE 2008 Rome Workshop’, In First
Int.Symp. on Marine Propulsors SMP09, Trondheim, Norway, June 2009.
2. RIJPKEMA, D. and VAZ G., ‘Viscous Flow Computations on Propulsors: Verification, Validation and Scale Effects’, In Proc. of Developments in Marine CFD, London, UK, March 2011.
3. VAZ, G., JAOUEN, F., and HOEKSTRA M., ‘Free-Surface Viscous Flow Computations. Validation of URANS
Code FRESCO’, In Proc. of OMAE2009, Honolulu, Hawaii, USA, June 2009.
4. PEREIRA, F., SALVATORE, F. and DI FELICE, F., ‘Measurement and Modelling of Propeller Cavitation in Uniform Inflow’, J. of Fluids Eng., 126:671–679, July 2004.
5. LI, D., ‘Validation of RANS Predictions of Open-water Performance of a Highly Skewed Propeller with Experiments’, In Proc. of Conference of Global Chinese Scholar on Hydrodynamics, 2006.
6. BOSSCHERS, J., VAZ, G., STARKE, A. R. and VAN WIJNGAARDEN, E., ‘Computational Analysis of Propeller Sheet Cavitation and Propeller-Ship Interaction’, RINA conference MARINE CFD2008, Southampton, UK, March 2008.
7. EÇA, L., VAZ, G. and HOEKSTRA, M., ‘A Verification and Validation Exercise for the Flow Over a Backward Facing Step’, In Proc. of ECCOMAS-CFD2010, Lisbon, Portugal, June 2010.
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