Last Louis Vuitton Cup and XXXI America’s Cup revealed that while the hull shapes were strongly similar for all the top teams’ boats, the bulb shapes were quite different, even if boat performances were very close one to each other. XXXII America’s Cup will adopt Version 5 of AC Rule, which is more restrictive than Version 4 as far as the hull shape, leaving the same degree of freedom to the design of appendages, so the bulb shape optimization will become an even more significant task in the development of a winning yacht. Currently CFD gives the way to lower the number of real life trial and error experiments. It is used to study the flow field of different geometries, giving results on the best one. What if we want to get the optimized solutions? In some cases, this is straight to obtain, we only need a few (less than 10) iterations. However, when the system gets more complex, the use of optimization software is required. The use of modern Computational Fluid Dynamics (CFD) codes coupled with automatic process integration and optimization tools allow us to explore the design space by evaluating a large number of design variations in a fast and smart way. It is important to consider not only the drag forces, but also the motions in waves and the related total mean resistance, considering that the location has changed and the weather/sea conditions are different from the Hauraki Gulf. In this work seakeeping tests of an IACC fully appended scale model have been carried out at the towing tank of the University of Trieste. The model has been tested in head waves, with wave lengths that match the encounter frequencies at Valencia site in upwind sailing conditions, calculated with an heading angle of 150 degrees. Three bulb shapes of different length have been designed using an automatic optimization procedure that, for each length chosen, minimizes the drag in calm water of the bulb and gives the lowest VCG. These bulbs have been used during the seakeeping tests to check the influence of their shape, mostly the length and related mass and added inertia, on the performance of the vertical motions of the yacht in waves.
Experimental Analysis of the Vertical Motions of a IACC Yacht with Calm Water Optimized Bulb
CONTENTO, GIORGIO;
2006-01-01
Abstract
Last Louis Vuitton Cup and XXXI America’s Cup revealed that while the hull shapes were strongly similar for all the top teams’ boats, the bulb shapes were quite different, even if boat performances were very close one to each other. XXXII America’s Cup will adopt Version 5 of AC Rule, which is more restrictive than Version 4 as far as the hull shape, leaving the same degree of freedom to the design of appendages, so the bulb shape optimization will become an even more significant task in the development of a winning yacht. Currently CFD gives the way to lower the number of real life trial and error experiments. It is used to study the flow field of different geometries, giving results on the best one. What if we want to get the optimized solutions? In some cases, this is straight to obtain, we only need a few (less than 10) iterations. However, when the system gets more complex, the use of optimization software is required. The use of modern Computational Fluid Dynamics (CFD) codes coupled with automatic process integration and optimization tools allow us to explore the design space by evaluating a large number of design variations in a fast and smart way. It is important to consider not only the drag forces, but also the motions in waves and the related total mean resistance, considering that the location has changed and the weather/sea conditions are different from the Hauraki Gulf. In this work seakeeping tests of an IACC fully appended scale model have been carried out at the towing tank of the University of Trieste. The model has been tested in head waves, with wave lengths that match the encounter frequencies at Valencia site in upwind sailing conditions, calculated with an heading angle of 150 degrees. Three bulb shapes of different length have been designed using an automatic optimization procedure that, for each length chosen, minimizes the drag in calm water of the bulb and gives the lowest VCG. These bulbs have been used during the seakeeping tests to check the influence of their shape, mostly the length and related mass and added inertia, on the performance of the vertical motions of the yacht in waves.Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
