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Keyword : design
Results 1 - 5 of 194
Experimental and numerical trimming optimizations for a mainsail in upwind conditions
This paper investigates the use of meta-models for optimizing sails trimming. A Gaussian process is used to robustly approximate the dependence of the performance with the trimming parameters to be optimized. The Gaussian process construction uses a limited number of performance observations at carefully selected trimming points, potentially enabling the optimization of complex sail systems with multiple trimming parameters. We test the optimization procedure on the (two parameters) trimming of a scaled IMOCA mainsail in upwind conditions. To assess the robustness of the Gaussian process approach, in particular its sensitivity to error and noise in the performance estimation, we contrast the direct optimization of the physical system with the optimization of its numerical model. For the physical system, the optimization procedure was fed with wind tunnel measurements, while the numerical modeling relied on a fully non-linear Fluid-Structure Interaction solver. The results show a correct agreement of the optimized trimming parameters for the physical and numerical models, despite the inherent errors in the numerical model and the measurement uncertainties. In addition, the number of performance estimations was found to be affordable and comparable in the two cases, demonstrating the effectiveness of the approach.
Fully Integrated Fluid-Structural Analysis for the Design and Performance Optimisation of Fibre Reinforced Sails
This paper presents an advanced and accurate integrated
system for the design and performance optimisation of
fibre reinforced sails, commonly named string sails,
developed by SMAR Azure. This integrated design system
allows sail designers not only to design sail shapes and the
reinforcing fibre paths, but also to validate the performance
of the flying sail shape and have accurate production
details including the overall sail weight, material used,
which means costs, and length of the fibre paths, which
means production time.
The SMAR Azure design and analysis method,
extensively validated and used to optimise several racing
and super-yacht sailing plans, includes a computationally
efficient structural analysis method coupled with a
modified vortex lattice method, with wake relaxation, to
enable a proper aeroelastic simulation of sails in upwind
conditions. The structural analysis method takes into
account the geometric non-linearity and wrinkling
behaviour of membrane structures, such as sails, the fibre
layout, the influence of battens, trimming loads and
interaction with rigging elements, e.g. luff sag calculation
on a headstay, in a timely manner.
Specifically, this paper presents an optimisation of a real
fibre reinforced membrane sailplan of an aluminium super
yacht, carried out in collaboration with Paolo Semeraro
(Banks Sails Europe). The optimisation process of the fibre
layouts led to a sensible reduction in maximum stress,
strain and displacement compared to the initial designs,
keeping the same fibre weight or slightly increasing it. The
results have been confirmed in the sailing tests, although no
exact measurements have been performed.
Advanced CFD-Simulations of Free-Surface Flows Around Modern Sailing Yachts Using a Newly Developed OpenFOAM Solver
While plain vanilla OpenFOAM(OF) has strong capabilities with regards to quite a few typical CFD-tasks, some problems actually require additional solvers and numerical methods for efficient computation of high-quality results. One of the fields requiring these additions is the computation of large-scale free-surface flows as found e.g. in naval architecture. This holds especially for the flow around typical modern yacht hulls, often planing, sometimes with surfacepiercing appendages. Particular challenges include, but are not limited to, breaking waves, sharpness of interface, numerical ventilation (aka streaking) and a wide range of flow phenomenon scales. A new OF-based application including newly implemented discretisation schemes, gradient computation and rigid body motion computation is described. The new code is validated against published experimental data; the effect on accuracy, computational time and solver stability is shown by comparison to standard OF-solvers (interFoam / interDyMFoam) and Star-CCM+. The code’s capabilities to simulate complex ”real-world” flows are shown on a well-known racing yacht design.
Insights from the Load Monitoring Program for the 2014-2015 Volvo Ocean Race
This paper describes insights into keel and rigging loads
obtained through a data acquisition system fitted on the
fleet of Volvo 65 yachts during the 2014-2015 Volvo
Ocean Race. In the first part, keel fin stress spectra are
derived from traces of canting keel ram pressures and keel
angle; these are reviewed and compared against equivalent
spectra obtained by applying methods proposed by Det
Norske Veritas - Germanischer Lloyd (“DNVGL”)
guidelines and the ISO 12215 standard. The differences
between stress spectra and their validity are discussed,
considering two types of keel: milled from a monolithic
cast of steel, and fabricated from welded metal sheets. The
second part discusses predicted and actual rigging working
loads for the Volvo 65 yachts, and considers how safety
factors vary between design loads proposed by DNVGL
and actual recorded loads.
Sailing is a sport and activity that takes a long time both
to learn and to master, as much of its competence-based
knowledge is acquired through experience. Experiencebased
learning is very important, time-intensive, and the
factors for success are often tacit and hidden. Should these
success factors become explicit and salient, learning would
occur faster and produce obvious competitive advantages.
This research was conducted by embedding on-going
research results into two competitive sailing teams racing
in different classes, one offshore keelboat racing with a
crew of eight, and a one-design Star-class racing yacht with
a crew of two. The data collection consisted of
observations, interviews, and video recordings. The results
were also verified with the crews to catch biases in the
analysis process. A jibe, a specific but common maneuver
was analyzed from the perspective of Common Ground
within Joint Activity.
Maneuvering a competitive offshore sail racer or a
previously Olympic Star-class yacht are tasks that fulfill
the requirements for Joint Activity. A high level of
Common Ground is required for the effective coordination
needed in order to perform at a high level and maintain the
safety of the crew and equipment.
Breakdowns in the coordination of maneuvers were
observed, although they must be recorded on video for
higher analysis reliability. To achieve greater validity,
more and different maneuvers should be considered within
the analysis.
By better understanding the factors for success, sail
racing teams can more quickly gain competence and thus
competitive advantages.
The research analyzes the teamwork found in sailing
from the perspective of Joint Activity and Common
Ground and provides insight into how to achieve
performance improvements more efficiently.