Simulation of the Aeroelastostatic Characteristics of an America’s Cup AC75 Mast/Mainsail System

The 30th America's Cup will be held in New Zealand, commencing in October 1999. For the first time a Swiss team, the FAST2000 Challenge of the Club Nautique Morgien, will compete. Three laboratories of the EPFL (Ecole Polytechnique Federale de Lausanne) are collaborating with FAST2000 in the design of the boat that will race in the Cup challenges. Present-day design of IACC racing yachts relies on the use of numerical flow simulations to obtain a competitive edge. The computation of the complex hydrodynamic and aerodynamic flows around sailing yachts provides valuable information to supplement the more conventional empirical and experimental design techniques. Such flow simulations, however, are extremely challenging and thus often require stateof-the-art numerical techniques and computer technology. A number of the issues critical to IACC yacht design are discussed, and various approaches described to address them through the use of advanced numerical flow simulation.

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Numerical Simulation using RANS-based Tools for America’s Cup Design

10.5957/csys-2003-007 ◽

2003 ◽

Author(s):

Geoff Cowles ◽

Nicola Parolini ◽

Mark L. Sawley

Keyword(s):

Design Process ◽

Water Surface ◽

Navier Stokes ◽

Computational Fluid Dynamics Simulations ◽

America’S Cup ◽

Dynamics Simulations ◽

École Polytechnique ◽

Cup Design ◽

Cup Drawing

The application of Computational Fluid Dynamics simulations based on the Reynolds Averaged Navier- Stokes (RANS) equations to the design of sailing yachts is becoming more commonplace, particularly for the America's Cup. Drawing on the experience of the Ecole Polytechnique Fédérale de Lausanne as Official Scientific Advisor to the Alinghi Challenge for the America’s Cup 2003, the role of RANS-based codes in the yacht design process is discussed. The strategy for simulating the hydrodynamic flow around the boat appendages is presented. Two different numerical methods for the simulation of wave generation on the water surface are compared. In addition, the aerodynamic flow around different sail configurations is investigated. The benefits to the design process as well as its limitations are discussed. Practical matters, such as manpower and computational requirements, are also considered.

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Calculation of Equilibrium Sail Shapes and Integrated Aerodynamic Properties for an America’s Cup AC75 Mast/Mainsail System

10.2514/6.2022-0563 ◽

2022 ◽

Author(s):

Richard W. Smith ◽

Jeffrey A. Wright

Keyword(s):

Aerodynamic Properties ◽

America’S Cup

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Modeling IACC Sail Forces by Combining Measurements with CFD

10.5957/csys-1993-010 ◽

1993 ◽

Author(s):

Jerome H. Milgram ◽

Donald B. Peters ◽

D. Noah Eckhouse

Keyword(s):

Scale Model ◽

Force Model ◽

Actual Performance ◽

Force Coefficients ◽

Prediction Program ◽

Induced Drag ◽

Load Cells ◽

Velocity Prediction ◽

America’S Cup ◽

Parasitic Components

A sailing dynamometer with a 42% scale model of an International America's Cup Class rig is used to measure sail forces and moments in actual sailing conditions. The sailing dynamometer is a 35-foot boat containing an internal frame connected to the hull by six load cells configured to measure all the forces and moments between the frame and the hull. All sailing rig components are attached to the frame, so that the sail forces are measured. Sail shapes in use are determined by computer-interfaced video. Computational fluid dynamics performed on the measured shapes provides the induced drag. This allows the measured drag to be decomposed into induced and form-and-parasitic components, which is necessary for generating a mathematical sail force model for a velocity prediction program (VPP). It is shown that VPP results using these new sail force coefficients are in better agreement with actual performance than are VPP results based on traditional sail force coefficients.

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Performance Prediction Hoftware for IACC Yachts

10.5957/csys-1993-005 ◽

1993 ◽

Author(s):

Eric C. Schlageter ◽

James R. Teeters

Keyword(s):

Performance Prediction ◽

Linear Optimization ◽

Viscous Drag ◽

Development Effort ◽

Added Resistance ◽

Induced Drag ◽

Software Development Effort ◽

Tank Test ◽

America’S Cup ◽

Wetted Area

The performance prediction software development effort undertaken by the Partnership for America's Cup Technology (PACT) is reviewed. First, PACT's origin, members, and mandate is covered, interspersed with a historical perspective of prediction software. Next, the new IACC rule with constraints is given. The hydrodynamic model format used in the software is described. Based on PACT tank test data, improved formulations for viscous drag, utilizing dynamic wetted area and length for canoe body drag and a 'stripping' method for appendage drag are presented. Corrections for Froude number and heel effects on induced drag are summarized. A new upwind sail model and added resistance model are discussed. The use of a race modeling program is illustrated with results from three separate design studies: a geosim family, a length scaling family, and an appendage study. Typical upright resistance, drag polar plots, lift plots, sea spectra, and added resistance data are presented. The final section describes current developments including speed enhancements, improved portability, and use of a multi-variable, non-linear optimization scheme to search the design space.

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