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Keyword : hydrostatic pressure
Results 1 - 5 of 6
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.
Hydrodynamic Aspects of Transom Stern Optimization
In this work an explanation for an optimum transom size is proposed which takes into account the hull shape between the midship and the transom. A systematic stern modification is performed to study the influence of the shape of waterlines and buttocks on the resistance components. The aft body of a hull is designed in a way that gives a possibility to separate the effects of waterline and buttock curvature and to study their effect on the flow. The Froude numbers are chosen to provide information for wetted- as well as dry-transom conditions. To evaluate the performance of the hulls the SHIPFLOW steady state Reynolds Averaged Navier-Stokes (RANS) code with a Volume of Fluid (VOF) surface capturing method is used in combination with the k-ω SST turbulence model. The code was first thoroughly validated for a transom stern hull. The paper focuses on hydrodynamic and hydrostatic resistance components of the transom and of the rest of the hull. Physical explanations are given for the effects of the aft body hull lines. The transom size, waterline curvature and rocker effects are analysed. The results show that the optimum transom size depends on the balance between the hydrostatic and hydrodynamic force components and the explanation for this is also given.
Sail Aerodynamics: Full-Scale Pressure Measurements on a 24-Feet Sailing Yacht
The aerodynamics of a Sparkman & Stephens 24-foot sailing yacht was investigated. Full-scale pressure measurements were performed on the mainsail and the genoa in upwind sailing conditions...
Full Scale Investigation of One-Design Class Catamaran Sails
This work is concerned with an experimental campaign carried out on a Tornado class catamaran. Full scale pressure measurements were taken on the boat mainsail both on the pressure and on the suction sides. Pressure taps were applied on the main sail accurately trying not to modify the flow field nor the flexibility of the sails. The distribution of the pressure taps is such that an accurate map of the mean pressure distribution on the sail surfaces has been reconstructed. Every pressure tap was coupled with a pressure transducer and the pressure values were acquired through an electronic scanning system, so that they can be considered to be simultaneous. Static pressure coefficient distribution over the sail span will be presented, giving an insight into the flow structure over the sails and precious information for validation of CFD codes.
Static pressure tests on sections of yacht hulls, manufactured to copy the structure of certain yachts
which failed in service due to slamming loads, are reported. The materials of construction were
aluminum, steel, plywood and fiberglass. The failure modes and pressures are discussed. In addition,
some tests in which mild steel plates, corresponding in construction to the mild steel hull
tested under static pressure, were loaded impulsively by the shock wave from an explosive charge
detonated in air. The design of hull plating should take into account the impulsive nature of the
loading, and the actual mode of failure. Neither the design impulse, however, nor the means for
predicting the hull plating response to it are available from the current literature. If resort is to be
made to the design of plating for simple static pressure, then a design pressure of at least 350 kPa
(51 psi) is suggested for the bottom plating of yachts of about 13 m (43 ft) length overall. This is
about five times the pressure required by the ABS Guide.