F Fossati's research while affiliated with Politecnico di Milano and other places

Publications (56)

Conference Paper
Full-text available
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 an...
Article
This paper presents an overview of the Lecco Innovation Hub project and in particular to the Sailing Yacht Lab project a 10 m length sailing yacht which aims to be a full scale measurement device in the sailing yacht research field. A description of scientific framework, measurement capabilities as well as of the principal design, building process,...
Conference Paper
Full-text available
In this paper, multi-disciplinary optimization techniques are applied to sail design. Two different mathematical models, providing the solution of the fluid-dynamic and the structural problems governing the behaviour of a complete sailplan, are coupled in a fluid-structure interaction (FSI) scheme, in order to determine the real flying shape of the...
Article
Full-text available
Sophisticated computational aero-hydro-elastic tools are being developed for simulating the dynamics of Floating Offshore Wind Turbines (FOWTs). The reliabilty of such prediction tools for designers requires experimental validation. To this end, due to the lack of a large amount of full scale data available, scale tests represent a remarkable tool....
Article
Sophisticated computational aero-hydro-elastic tools are being developed for simulating the complex dynamics of Floating Off-shore Wind Turbines (FOWTs). The reliabilty of such prediction tools for designers requires experimental validation. To this end, due to the lack of full scale data available, scale tests represent a remarkable tool. Moreover...
Article
Larger main dimensions, superior comfort requests and higher manoeuvrability characteristics focus mega-yacht designer attention towards hull and superstructure aerodynamic performance. Windage evaluation of very high superstructure, aerodynamic load assessment, and accurate air flow simulation are considered very important in the design procedure...
Article
With the sustainability movement, vegetated building envelopes are gaining more popularity. This requires special wind effect investigations, both from sustainability and resiliency perspectives. The current paper focuses on wind load estimation on small- and full-scale trees used as part of green roofs and balconies. Small-scale wind load assessme...
Conference Paper
The Sail and Life Training Society is building a new purpose-designed 35m wooden sail-training schooner for unrestricted foreign-going operations. Working with an international team of consultants, SALTS has initiated an ambitious agenda of analytical and experimental investigations to support design, including a parametric study of hull form as it...
Article
Aerodynamic forces have been often neglected in ship design. At present, windage evaluation, aerodynamic load assessment, and accurate air flow simulation become to be considered in the design procedures of ships and small craft. They are related to main engines and DPS horsepower assessment as well as to superstructure design. This paper, based on...
Article
Full-text available
The aerodynamic behavior of a 48' yacht rig 3D scale model was characterized by means of wind tunnel tests. The experimental program, performed in the Politecnico di Milano Twisted Flow Wind Tunnel, allowed the aerodynamic forces to be characterized using forced motion tests and the aeroelastic behavior of the sail plan to be studied. Preliminary r...
Conference Paper
This paper describes selected results collected during the wind tunnel tests carried out at Politecnico di Milano Wind Tunnel on the deck sectional model of the Messina Strait Bridge. It is a long span suspension bridge characterized by a multi box deck. Aerodynamic forces and surface pressure distributions have been measured in order to characteri...
Conference Paper
This paper presents the up to date developments of wind tunnel testing activities carried out in the Politecnico di Milano Twisted Flow Wind Tunnel aimed to provide an enhanced experimental database concerning sails aerodynamic behavior in dynamic conditions. In particular yacht induced pitch motion effects on sails forces have been investigated by...
Article
This work is concerned with the aerodynamic characterization of a cable-stayed bridge tower in free-standing configuration; experimental tests were performed at Politecnico di Milano Wind Tunnel under smooth and turbulent flow conditions. The aerodynamic behavior of the tower was investigated through static and dynamic tests on a 1:30 scale section...
Article
This paper presents two different mathematical approaches able to reproduce unsteady sail aerodynamics taking into account three dimensional effects and unsteady mainsail-jib interaction. Aim of the proposed methods is to develop a time domain based nonlinear numerical model which can be easily incorporated into a Dynamic Performance Prediction Pro...
Chapter
This work presents a feasibility study for trustable and affordable CFD analysis of aerodynamic indices of racing sailing yachts. A detailed reconstructed model of a recent America's Cup class mainsail and asymmetrical spinnaker under light wind conditions has been studied using massive parallel RANS modeling on 128 CPUs. A detailed comparison betw...
Conference Paper
The aerodynamic behaviour of a 48’ yacht rig 3D scale model was characterized by means of wind tunnel tests. The experimental campaign, performed in the Politecnico di Milano Twisted Flow Wind Tunnel, allowed to characterize the aerodynamic forces using forced motion tests and to study the aeroelastic behaviour of the sailplan. Preliminary results...
Article
A new measuring system was developed at the Mechanical Department of the Politecnico di Milano to measure displacements of aeroelastic models during wind tunnel experiments relying on image processing. The system is able to track the variation of the 3D coordinates of model's points that are identified post processing the images recorded by CCD dig...
Article
RANS code has been applied to an America's Cup Class Yacht to investigate sail-ing performance in downwind configuration. Apparent wind angles at 45°, 105° and 120° are reported, sailed with mainsail and asymmetrical spinnakers. Numerical results are in good agreement with wind tunnel data. A large mesh investigation have been performed, ranging fr...
Conference Paper
This paper presents research activities carried out by the authors to investigate aerodynamic behaviour of several unconventional saiplans in comparison to the sloop traditional solution. In particular an "A - shaped" mast, placed in the stern area of the yacht has been considered in single-jib and double-jib configurations. Wind Tunnel tests and p...
Conference Paper
Aim of the present paper is to present some results concerning the relationship between upwind flying shapes geometry and sail plan aerodynamic performance and to provide an experimental database to the scientific community for numerical simulation benchmarking activities concerning upwind sails aerodynamics. In particular experimental data are ava...
Article
As train speed increases, contact wire irregularity affects the quality of current collection more and more. The possibility of achieving the maximum operating speed depends also on the maintenance level of the overhead line (OHL). In the present paper, the influence of contact wire irregularity (in terms of vertical deviation of its position) is i...
Conference Paper
The current collection for the traction motor of trains is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. As the train speed increases, the variation of contact force exchanged between the pantograph and the OHL, dependent on their dynamic interaction, becomes greater....
Conference Paper
Full-text available
Aim of this paper is to describe research activities carried out at Politecnico di Milano Twisted Flow Wind Tunnel with partial funding from the ORC in order to investigate the performance of upwind sails: in particular a series of rig planform variations in mainsail roach and jib overlap have been tested in order to overcome some perceived inequit...
Chapter
L?imbarcazione a vela, in navigazione, vede un vento relativo (detto apparente) determinato dalla somma del vento assoluto (detto vero) e del vento di trascinamento associato al moto della barca (detto di velocita?). In condizioni normali, il modulo del vento vero e di quello di velocita? sono dello stesso ordine di grandezza. Pertanto, diventa di...
Article
Full-text available
Trains current collection for traction motors is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. The normal force by which the collector presses against the contact wire ensures the contact pressure for the electrical contact. As the train speed increases, the variation...
Conference Paper
An active control for a high speed train pantograph is proposed in order to improve power collection at high speed (i.e. V>220 km/h) allowing the speedup of the existing lines. The control is based on an available commercial actuator, and its feasibility and effectiveness have been investigated by means of numerical simulation. For this purpose, th...
Article
The catenary-pantograph system and its dynamic behaviour play a decisive role for high speed trains from the power collecting point of view. The decisive criterion for assessing the contact quality is to reduce the contact force variability as far as possible. In this paper active pantograph elements are introduced in order to improve the system pe...
Article
This paper is concerned with the dynamic design of an important transmission line overhead crossing. It presents the different problems which have to be taken into account to assess the correct and safe design of towers, damping devices, insulator suspension and tension sets. Analytical tools used to simulate these problems (wind excitation and exc...
Article
This paper presents the state of the art of the research on wind-induced vibrations of cylinders with circular section in single or multiple arrangements. The typical problems of overhead transmission lines are discussed and methodologies used to simulate them are summarized in view of their application also in the field of bridge hangers or stays....
Article
This paper deals with an analytical approach to define the dynamic behaviour of a cable under vortex shedding excitation in turbulence conditions. The conductor is schematized by f.e.m. The time history of the velocity field is computed in any nodal point of the schematization. The vortex shedding effects are reproduced by means of equivalent non l...
Article
Aim of this paper is to describe changes and developments in the ORC International Rule (including work in progress) with particular reference to sail aerodynamics. After a brief introduction of the most important modifications between IMS and ORC International adopted in order to give a response to some of perceived rating inequities under the Int...

Citations

... The unsteady Reynolds-averaged Navier-Stokes (URANS) approach yields reasonably accurate numerical results and performs reliable flow-field simulations for facilitating hydrodynamic and aerodynamic analyses of ships (with and without superstructures) with reasonable mesh sizes and within acceptable computation time [25][26][27]. This approach was, therefore, considered for use in numerical simulations performed in this study. ...
... No forces are measured. Fossati et al. (2010) present two mathematical approaches to model a pitching sailplan, including three dimensional effects and mainsail-jib interaction. The models are then validated against dynamic wind tunnel tests, showing in general good agreement. ...
... Wind tunnel studies (Flay, 1996a,b;Lasher et al., 2005) have proven to a be a great tool to study the aero-elastic problem of sails in wind. More recently, wind tunnel has been also used to study the Fluid Structure Interaction (FSI) phenomena that occur with sails in dynamic conditions in pitching (Fossati and Muggiasca, 2009) or with a dynamic trimming (Aubin et al., 2016). The recent increase in computation capabilities has allowed the development of accurate CFD tools to model the FSI of sails (Braun and Imas, 2008;Lasher and Sonnenmeir, 2008). ...
... In this scenario, measurements on rigid scale models of sail planes have been recently conducted either upwind (Viola and Flay, 2011) or downwind , as well as "on-the-water", with properly instrumented sails (respectively (Viola and Flay, 2010), (Bayati et al., 2017) and (Viola and Flay, 2013)). Flying shapes detection systems have been included to associate 3D geometry to pressure measurements, through camera-based VSPARS system (Motta et al., 2014), time-of-flight devices (Vandone, 2016) or Go-Pro based cameras (Deparday et al., 2016), along with local load measurements (load cells or straing gauges on the rigging), or even global force measurements, as in (Fossati et al., 2015a), where a 6-components dynamometric frame bears the entire sail-plane providing the integral aerodynamic forces simultaneously with pressure and sail shapes (Fossati et al., 2016;Masuyama, 2013). Nevertheless, a reliable comparison between wind-tunnel data versus full-scale ones is still to be achieved, since different setup and experimental approaches are usually carried out making the direct comparison not straightforward (e.g. ...
... The shape of the hysteresis loops, and therefore the amount of energy that is transferred to the sail, depends on the non-dimensional reduced velocity (apparent wind velocity divided by pitching frequency and sail chord) experienced by the sails. In previous work, Fossati and Muggiasca [27] also provided a rheological model based on springs, dampers, Coulomb friction elements, bump stops, etc. that allowed the aero-elastic forces to be computed. Fortunately for those researchers that neglect these dynamic effects, the centres of the hysteresis loops are quite well approximated by the quasi-static aerodynamic coefficients. ...
... Bow rake is smaller according to contemporary design trends and a stern platform is fitted. Calm water and aerodynamic performance assessments are reported in Oliviero (2009) and Fossati et al. (2013). Warped scale model is relative to an existing 40 ft L OA motor yacht, scale ratio λ¼10. ...
... The model deformation will be evaluated, at the most significant test conditions, by photogrammetry techniques. The principle is to obtain a stereoscopic visualization by taking a couple of images simultaneously using two cameras installed with different angle respect to the model [11]. The 3D geometric reconstruction process consists in recognizing the position of a matrix of markers, opportunely placed on the model surface, by the visual 3D evaluation of the displacement of this discrete number of points respect to their known static positions. ...
... Froude-Reynolds conflict [6]). According to this methodology, aerodynamic loads or hydrodynamic loads are reproduced exploiting a dedicated facility (respectively wind tunnel [7,8] or ocean basin [9,10]) while complementary forces are computed in real-time and provided to the scale model by means of a proper actuation system. Recently, a significant interest has been put on the design of specific control strategies for floating wind turbines. ...
... The new procedure is parametric and fully automated, and it only needs some input data to calculate the flying shape and the loads on the sail. As it is known, to perform a numerical FSI analysis, two embedded problems, aerodynamic and structural, need to be solved together [29]. In this study, to solve the aerodynamic and structural problems, the commercial CFD solver Ansys CFX and the Ansys Static Structural solver were used, respectively. ...
... Moreover, for 3D reconstructions in a wind tunnel, more than one camera or stereo camera (four cameras in [24]) can be required, leading to a quite expensive and cumbersome setup. On the contrary, the accuracy can significantly decrease in the case of the application of Light Detection and Ranging (LIDAR) sensors, as in [26]. However, in this case, the measurement system is based on a custom sensor, which can be quite expensive in terms of instrumentation and involves considerable work to set up the system. ...