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Author : M. Malandra
Results 1 - 2 of 2
Pressure Measurements on Yacht Sails: Development of a New System for Wind Tunnel and Full Scale Testing
The paper presents an overview of a joint project
developed among Politecnico di Milano, CSEM and North
Sails, aiming at developing a new sail pressure measurement
system based on MEMS sensors (an excellent compromise
between size, performance, costs and operational
conditions) and pressure strips and pads technology. These
devices were designed and produced to give differential
measurement between the leeward and windward side of the
sails. The project has been developed within the Lecco
Innovation Hub Sailing Yacht Lab, a 10 m length sailing
dynamometer which intend to be the reference
contemporary full scale measurement device in the sailing
yacht engineering research field, to enhance the insight of
sail steady and unsteady aerodynamics [1].
The pressure system is described in details as well as the
data acquisition process and system metrological validation
is provided; furthermore, some results obtained during a
wind tunnel campaign carried out at Politecnico di Milano
Wind Tunnel, as a benchmark of the whole measuring
system for future full scale application, are reported and
discussed in details.
Moreover, the system configuration for full scale testing,
which is still under development, is also described.
It’s well known that large differences commonly exist between a computer based original design shape and the resulting flying shapes of offwind sails. Fluid-structure interaction codes based on CFD and FE techniques are nowadays under development and they represent appealing tools useful to close this gap: in fact potential improvements to the offwind sail design process could be provided by developing an offwind sail design database (a collection of baseline designs appropriate for different applications) based upon representative flying shapes rather than present style based upon design shapes. Up to date numerical codes still need a massive validation work and both wind tunnel tests as well as on water testing at full scale can give a substantial contribution, supposing that reliable flying shapes are provided reflective of the realistic sailing and trim conditions. This paper presents a new tool based on noncontact methods which allows for measuring sail flying shapes in the wind tunnel environment as well as at full scale in real life conditions. The proposed method has been validated during a wind tunnel campaign on both symmetric and asymmetric spinnakers carried out at Politecnico di Milano during an Offshore Racing Congress project aimed at revising offwind sails aerodynamic coefficients and ORC VPP aerodynamic model. Some results are shown comparing design shapes versus flying shapes and potential improvements to the offwind sail design process by developing an offwind reference sail design database are discussed.
