A research on A-Class sails design awarded by the ANSYS “Hall of Fame” competition
A research project about the development of an A-Class sail design methodology was selected last April by the SHAPE (SME HPC Adoption Programme in Europe) European Commission funded programme (http://www.prace-ri.eu/shape-second-call-results). The work is carried out by the aerospace engineering company Design Methods (www.designmethods.aero). A description of the design tool under development and an image representative of its typical numerical analysis was recently awarded by ANSYS (the global leader in engineering simulation) as one of the worldwide best-in-class CAE (Computer Aided Engineering) application (http://www.ansys.com/Other/Hall-of-Fame/Design-Methods).
The objective of the project is to develop a design procedure able to optimize the sail shape including, in the analysis process, the capability to estimate the performance of the complete boat and its sailing conditions (velocity and true wind angle). In very simple words, the method consists in representing all the possible geometric configuration (sail shape, setting, planform , mast geometry, appendage configuration, rudder, etc.) by a set of numbers managed by a mathematical decision making criterion that, in an automatic process, searches the values combination to which corresponds the fastest boat. The development of a tool like this requires very high competences in several disciplines as aerodynamics, numerical optimization, CAD (Computer Aided Design) modelling and computer programming. In the company view, the project is aimed to demonstrate the Design Methods capability to transfer such competences in engineering application other than aerospace.
A similar procedure, applied to the optimization of an AC72 wing sail setting, was already presented in March 2015 by Ubaldo Cella (owner of Design Methods and responsible of the project) at the fifth High Performance Yacht Design international conference (http://www.hpyd.org.nz/) in Auckland (New Zealand) and published in the conference proceedings. The SHAPE method, even if with several analogies with the AC72 procedure, is strongly customized to the A-Class configuration, it focuses high attention to the physics modelling of the VPP (Velocity Prediction Program) and is oriented to the software flexibility in order to facilitate the adaptation to any kind of platform configurations.
Little more in technical details, the method integrates, within a numerical optimization procedure, an in house developed VPP and a CFD (Computational Fluid Dynamics) solution of the sail aerodynamic. The objective function is the maximization of the boat VMG (Velocity Made Good). The hull is modelled by analytical formulations both taken from literature and developed by a comparison with a matrix of validated multiphase CFD solutions of the hull at several attitudes and leeway angles. The procedure involves the possibility to include a very large number of design variables, from foils and rudders configuration to mast and sail geometry. It dedicates particular efforts in the implementation of numerical solutions aimed to improve the efficiency of the computation which is an aspect particularly critical in automatic optimization procedures. This know how derives from experiences gained in about fifteen years spent implementing design tools for aircraft wing, flaps, winglet design and devices installation within industrial aircraft design programs and European research projects.
The procedure currently under tests is setup on a non-flying A-Cat configuration and models dagger boards and rudders applying methods from aeronautical preliminarily design literature. When completed, the modularity of the software will allow to optimize any type of boat, including a flying configuration integrating foils CFD analyses.