Simulation-driven design of a fast monohull

ABSTRACT

A fast monohull was designed and optimized, using CAESES® for parametric modeling and optimization coupled to STAR-CCM + for free-surface RANS simulations. The boat is a 9.5ton pilot boat, featuring tunneled propellers, shafts and rudders. The optimizations were undertaken for thrust at design speed of 27.5kn. The boat was free to trim and rise, utilizing an overset grid for high resolution and acceptable turn-around time. Propulsion was taken into account via an actuator disc, balancing resistance and thrust. The geometry of the bare hull and tunnel were varied during the optimizations, using fully-parametric models. A systematic comparison of numerical and experimental data was undertaken. The experiments were conducted with the high-speed carriage at TU Berlin, using a 3.5m fully-appended self-propelled model. The optimizations comprised Design-of-Experiments, deterministic searches, surrogates and global strategies. Substantial improvements were found with variants being more energy-efficient than a representative baseline. The paper discusses modeling, simulations and optimizations along with selected results.

KEYWORDS:

• Simulation-driven Design (SDD)
• parametric modeling
• formal optimization
• Computational Fluid Dynamics (CFD)
• Computer Aided Engineering (CAE)
• planing boat
• Design-Of-Experiment (DoE)
• machine learning (ML)

Acknowledgements

The MarTERA project AutoPlan (www.auto-plan.net) brings together partners from Germany, Turkey and Italy. From Germany these are FRIENDSHIP SYSTEMS (www.friendship-systems.com), Schiffbau-Versuchsanstalt Potsdam (SVA, www.sva-potsdam.de) and Technical University Berlin (TU Berlin, www.tu-berlin.de) while from Turkey these are Piri Reis University (www.pirireis.edu.tr), Offshore Engineering Solutions (OES, www.oesdenizcilik.com) and UZMAR (uzmar.com) plus, as associated partner from Italy, Consiglio Nazionale delle Ricerche – Institute of Marine Engineering (CNR-INM, www.inm.cnr.it). The authors would like to thank their colleagues from these organizations, in particular, Nalan Erol from UZMAR for leading the AutoPlan project and Prof. Dr. Andrés Cura from TU Berlin for conducting the towing tank tests with his team, using a scale model built at SVA Potsdam. From FRIENDSHIP SYSTEMS we would like to thank Claus Abt and Carl Benz for their support in parametric modeling and grid generation, respectively. Finally, from Siemens we would like to thank Dr. Miles Wheeler, Aaron Godfrey and Dr. Dejan Radosavljevic for their support throughout the project, in particular for sharing their know-how of running numerical flow simulations for planing boats.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 The engines ordered by the shipyard, however, are expected to allow for higher speeds. At 32kn and for a displacement of 9.5ton the volumetric Froude number reaches 3.63 at which point this criterion would be fully met, too

2 Harries et al. (2015) presents on overview of the various approaches of parametric modeling, distinguishing fully-parametric and partially-parametric modeling. The former assumes that the entire shape of interest is determined by parameters. The latter is built on existing shapes, wherever they may come from, and just uses parameters to evoke local modifications, for instance, by means of radial basis functions as presented in Harries and Uharek (2021). Hybrid modeling approaches combine the better of the two worlds, depending on the modeling task at hand.

3 An appreciation of the model can be gained interactively from the corresponding webApp at www.friendship-systems.com/products/web-apps

4 also known as Chimera grid

5 and to make reaching any further improvement challenging

6 Everything shown above the dashed line in Figure 33 can be considered simulation-based design while the various processes and results below the dashed line should be seen as simulation-driven design.

7 The subtle elongation of the tunnel is investigated numerically via a systematic change which shows no detrimental effects of performance.

8 This design is model-tested, too, for comparison to the new baseline.

Additional information

Funding

Parts of the work presented in this paper were realized within the research and development project AutoPlan (Automatic Navigation Assistance System for Planing and Semi-planing Crafts), funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK) on the orders of the German Bundestag and PtJ as the conducting agency [FKZ 03SX523A].