scholarly journals Recent Advances in Sailing Yacht Aerodynamics

2013 ◽  
Vol 65 (4) ◽  
Author(s):  
Ignazio Maria Viola
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Optimization Techniques ◽  
Prediction Program ◽  
Research Areas ◽  
Recent Advances ◽  
Flow Device ◽  
Velocity Prediction ◽  
Sailing Yacht ◽  
Future Work

The analysis of sailing yacht aerodynamics has changed dramatically over the last 15 years and has enabled significant advances in performance prediction. For instance, the growth of computational fluid dynamics has significantly changed the way high-performance sails are designed. Three-dimensional mathematical models of fully rigged sail plans and the visualization of the turbulent unsteady flow pattern around them are now quite common, whereas ten years ago such a simulation would have been very rare and 20 years ago it would have been impossible. The parallel development of optimization techniques has resulted in new sail and yacht design methods. Changes in the experimental techniques have been as dramatic as in the numerical techniques. The introduction of the twisted flow device, the real-time velocity prediction program, and the most recent pressure measurements have allowed a step change in the potentialities of experimental sail aerodynamics. This paper aims to review the recent advances in sail aerodynamics and to highlight potential research areas for future work.

scholarly journals Towards Continuous Production of Shaped Honeycombs

2018 ◽  
Author(s):  
Sam E. Calisch ◽  
Neil A. Gershenfeld
Keyword(s):  
High Performance ◽  
Continuous Production ◽  
Continuous Process ◽  
Three Dimensional ◽  
Sandwich Panels ◽  
Performance Space ◽  
Bending Loads ◽  
Future Work ◽  
The Impact ◽  
Parallel Folding

Honeycomb sandwich panels are widely used for high performance parts subject to bending loads, but their manufacturing costs remain high. In particular, for parts with non-flat, non-uniform geometry, honeycombs must be machined or thermoformed with great care and expense. The ability to produce shaped honeycombs would allow sandwich panels to replace monolithic parts in a number of high performance, space-constrained applications, while also providing new areas of research for structural optimization, distributed sensing and actuation, and on-site production of infrastructure. Previous work has shown methods of directly producing shaped honeycombs by cutting and folding flat sheets of material. This research extends these methods by demonstrating work towards a continuous process for the cutting and folding steps of this process. An algorithm for producing a manufacturable cut-and-fold pattern from a three-dimensional volume is designed, and a machine for automatically performing the required cutting and parallel folding is proposed and prototyped. The accuracy of the creases placed by this machine is characterized and the impact of creasing order is demonstrated. Finally, a prototype part is produced and future work is sketched towards full process automation.

scholarly journals High Froude Number Experimental Investigation of the 2 DOF Behavior of a Multihull Float in Head Waves

2021 ◽  
Vol 6 (01) ◽  
pp. 1-20
Author(s):  
Paul Kerdraon ◽  
Boris Horel ◽  
Patrick Bot ◽  
Adrien Letourneur ◽  
David David Le Touzé
Keyword(s):  
High Performance ◽  
Good Representation ◽  
Prediction Program ◽  
Modeling Approach ◽  
Head Waves ◽  
Wide Range ◽  
Dynamic Velocity ◽  
Velocity Prediction ◽  
High Froude Number ◽  
Stability Issues

Dynamic Velocity Prediction Programs are taking an increasingly prominent role in high performance yacht design, as they allow to deal with seakeeping abilities and stability issues. Their validation is however often neglected for lack of time and data. This paper presents an experimental campaign carried out in the towing tank of the Ecole Centrale de Nantes, France, to validate the hull modeling in use in a previously presented Dynamic Velocity Prediction Program. Even though with foils, hulls are less frequently immersed, a reliable hull modeling is necessary to properly simulate the critical transient phases such as touchdowns and takeoffs. The model is a multihull float with a waterline length of 2.5 m. Measurements were made in head waves in both captive and semi-captive conditions (free to heave and pitch), with the model towed at constant yaw and speed. To get as close as possible to real sailing conditions, experiments were made at both zero and non-zero leeway angles, sweeping a wide range of speed values, with Froude numbers up to 1.2. Both linear and nonlinear wave conditions were studied in order to test the limits of the modeling approach, with wave steepness reaching up to 7% in captive conditions and 3.5% in semi-captive ones. The paper presents the design and methodology of the experiments, as well as comparisons of measured loads and motions with simulations. Loads are shown to be consistent, with a good representation of the sustained non-linearities. Pitch and heave motions depict an encouraging correlation which confirms that the modeling approach is valid.

scholarly journals Review on Blue Perovskite Light-Emitting Diodes: Recent Advances and Future Prospects

2021 ◽  
Vol 8 ◽  
Author(s):  
Chuangye Ge ◽  
Qianru Fang ◽  
Haoran Lin ◽  
Hanlin Hu
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Three Dimensional ◽  
Device Structure ◽  
Promising Alternative ◽  
Light Emitting ◽  
Deep Blue ◽  
Recent Advances ◽  
Technical Issues

Perovskite-based light-emitting diodes (PLEDs) have emerged as a promising alternative owning to the excellent optoelectronic properties including narrow emission linewidths, high photoluminescence quantum yield (PLQY), tunable emission wavelength, and high color purity. Over the past several years, significant progress has been obtained for green, red, and near-infrared PLEDs with a high external quantum efficiency (EQE) of over 20%. However, the development of blue PLEDs has been limited by several technical issues including poor film quality, inefficient device structure, higher trap density, and so on. To overcome these drawbacks with improved PLQY and EQE, we summarize and analyze the recent advances towards the development of three dimensional (3D), two dimensional (2D) and quasi-2D perovskites film employing composition and/or dimensional engineering. Moreover, the utilization of perovskite nanocrystals (PNCs) is also considered as a feasible strategy for the realization of high-performance blue PLEDs. We systematically evaluate the performance of sky-blue, pure-blue and deep blue PLEDs based on different perovskite materials. Finally, future prospective are proposed to promote the development of efficient blue PLEDs.

Toward Numerical VPP with the Full Coupling of Aerodynamic and Hydrodynamic Solvers for ACC Yachts

2005 ◽  
Author(s):  
Erwan Jacquin ◽  
Yann Roux ◽  
Bertrand Allessandrini
Keyword(s):  
Degrees Of Freedom ◽  
Computational Method ◽  
Motion Equations ◽  
Towing Tank ◽  
Six Degrees Of Freedom ◽  
Prediction Program ◽  
Velocity Prediction ◽  
Sailing Yacht ◽  
Full Coupling ◽  
Classical Interpolation

The classical approach of Velocity Prediction Program is to find the balance of Hydrodynamic and aerodynamic sensors acting on the yacht to determine sailing conditions and associated performance. Usually, this approach is based on the data given by towing tank, wind tunnel or numerical computations. We present in this paper the unsteady coupling between an hydrodynamic RANSE with free surface solver and a panel aerodynamic solver that allow to directly find the sailing condition of the yacht, and its performances, compute bay solving the six degrees of freedom motion equations of the ship in the hydrodynamic solver. The main advantage of this computational method is the decrease of numerical evaluation, compared to the classical interpolation approach to determine performances of a hull, and to directly rank several hills in the term of performances and not only in the term of drag in fixed conditions. Further, improvements will allow to simulate unsteady maneuvering of sailing yacht, and focus will for example on restart behavior after tacking, dynamic behavior in waves.

Recent advances in metal oxide/hydroxide on three-dimensional nickel foam substrate for high performance pseudocapacitive electrodes

2020 ◽  
Vol 21 ◽  
pp. 242-249 ◽  
Author(s):  
Raphael M. Obodo ◽  
Nanasaheb M. Shinde ◽  
Ugochi K. Chime ◽  
Sabastine Ezugwu ◽  
Assumpta C. Nwanya ◽  
...  
Keyword(s):  
Metal Oxide ◽  
High Performance ◽  
Nickel Foam ◽  
Three Dimensional ◽  
Oxide Hydroxide ◽  
Recent Advances

Design Space Exploration of 3D CPUs and Micro-Fluidic Heatsinks With Thermo-Electrical-Physical Co-Optimization

2015 ◽  
Author(s):  
Caleb Serafy ◽  
Ankur Srivastava ◽  
Avram Bar-Cohen ◽  
Donald Yeung
Keyword(s):  
Energy Efficiency ◽  
High Performance ◽  
Architectural Design ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
New Technology ◽  
Three Dimensional ◽  
Optimization Techniques ◽  
3D Design

Three-dimensional integration (3D IC) is a new technology that shows great potential for high performance and energy efficiency. However past work has shown that 3D ICs suffer from serious thermal issues, and advanced cooling solutions such as micro-fluidic cooling are necessary to realize the true potential of these systems. The interactions between thermal, electrical and physical aspects of a 3D design with micro-fluidic cooling are substantial, and a comprehensive co-design approach to address them simultaneously is a must. Such co-design techniques are required throughout the design process, including during architectural design space exploration (DSE) in order to ensure that optimal design choices are not overlooked. In this paper we propose a DSE framework for 3D CPUs with micro-fluidic cooling that applies electro-thermal optimization techniques to the circuit layout and the heatsink design. By considering such physical optimization techniques we provide a more accurate view of a 3D architecture’s thermal and timing feasibility, as well as its performance and energy efficiency. Using our proposed thermo-electrical-physical co-design DSE framework we are able to improve performance by 1.54x and energy efficiency by 1.26x.

scholarly journals A Performance Depowering Investigation for Wind Powered Cargo Ships Along a Route

2020 ◽  
Vol 5 (01) ◽  
pp. 47-60
Author(s):  
Fredrik Olsson ◽  
Laura Giovannetti ◽  
Sofia Werner ◽  
Christian Finnsgård
Keyword(s):  
Degrees Of Freedom ◽  
Structural Integrity ◽  
Prediction Program ◽  
Force Magnitude ◽  
Speed Performance ◽  
Velocity Prediction ◽  
Sailing Yacht ◽  
The Impact ◽  
Ship Speed ◽  
A Performance

Abstract. For a sailing yacht, depowering is a set of strategies used to limit the sail force magnitude by intentionally moving away from the point of maximum forward driving force, potentially reducing the ship speed. The reasons for doing this includes among others; reduction of quasi-static heeling angle, structural integrity of masts and sails and crew comfort. For a wind powered cargo ship, time spent on a route is of utmost importance. This leads to the question whether there is a performance difference between different depowering strategies and if so, how large. In this research, a wind-powered cargo vessel with rigid wings is described in a Velocity Prediction Program (VPP) with four-degrees of freedom, namely surge, sway, roll and yaw, with a maximum heel angle constraint. The resulting ship speed performance for different depowering strategies are investigated and the implications in roll and pitch-moments are discussed. The wind conditions when depowering is needed are identified. A statistical analysis on the probability of occurrence of these conditions and the impact of the different depowering strategies on the required number of days for a round-trip on a Transatlantic route is performed.

Hull - Appendage Interaction of a Sailing Yacht, Investigated with Wave Cut Techniques

1997 ◽  
Author(s):  
Jonathan R. Binns ◽  
Kim Klaka ◽  
Andrew Dovell
Keyword(s):  
Approximate Method ◽  
Wave Pattern ◽  
Wave Resistance ◽  
Full Scale ◽  
Research Centre ◽  
Cooperative Research ◽  
Prediction Program ◽  
Velocity Prediction ◽  
Sailing Yacht

The research explained in this paper was carried out to investigate the effects of hull-appendage interaction on the resistance of a sailing yacht, and the effects these changes have on the velocity prediction for a sailing yacht. To accomplish this aim a series of wave-cut experiments was carried out and analysed using a modified procedure. The processed results have then been incorporated into an existing velocity prediction program. For the purposes of this research two variables were investigated for the Australian Maritime Engineering Cooperative Research Centre (AMECRC) parent model 004, a model derived from the Delft IMS series of yachts. Wave-cut procedures inevitably raise questions about scaling procedures for full scale extrapolation as the inviscid wave-pattern resistance is calculated to be less than the residuary or wave resistance. These questions have been dealt with by an approximate method, briefly explained in this paper.

RVPP: Sailing Yacht Performance Prediction fully integrated into a RANSE based flow code

2011 ◽  
Author(s):  
Christoph Böhm ◽  
Kai Graf
Keyword(s):  
Equations Of Motion ◽  
Flow Simulation ◽  
Body Motion ◽  
Fully Integrated ◽  
Prediction Program ◽  
Velocity Prediction ◽  
Sailing Yacht ◽  
Ranse Solver ◽  
Hydrodynamic Data ◽  
Physical Phenomena

One of the most important tools in today’s sailing yacht design is the Velocity Prediction Program (VPP). VPPs calculate boat speed from the equilibrium of aero and hydrodynamic flow forces. Consequently their accuracy is linked to the accuracy of the aero- and hydrodynamic data used to represent a yacht. These data are usually derived from experimental or CFD results and processed by means of linearization and interpolation to represents the actual sailing state of the yacht, this interpolation being a source of inaccuracy. Furthermore, viscosity related effects are often estimated by simplified theoretical or empirical models potentially neglecting complex physical phenomena. The paper proposes a method circumventing these inaccuracies. It is based on the idea to directly derive Sailing Yacht performance from a RANSE flow simulation. This is done by coupling the prediction of sail forces with the hydrodynamic forces calculated by the flow code and solving the resulting imbalance in the equations of motion in the RANSE solver. The paper discusses implementation steps for the inclusion of sail forces and body motion into the flow code as well as calculation and grid setup. Results of the method christened RVPP are shown for a generic yacht design and are compared with results from a classical VPP approach on the same design. The paper finishes with a discussion of the pros and cons of the method and an overview at future development steps of RVPP.

Approximation of the Calm Water Resistance on a Sailing Yacht Based on the 'Delft Systematic Yacht Hull Series'

1999 ◽  
Author(s):  
J. A. Kenning ◽  
U. B. Sonnenberg
Keyword(s):  
Water Resistance ◽  
Force Production ◽  
Data Set ◽  
Side Force ◽  
Prediction Program ◽  
Resistance Increase ◽  
The Past ◽  
Calm Water ◽  
Velocity Prediction ◽  
Sailing Yacht

Over the past years a considerable extension has been given to the Delft Systematic Yacht Hull Series (DSYHS) The DSYHS data set now contains information about both the bare hull and appended hull resistance in the upright and the heeled condition, the resistance increase due to the longitudinal trimming moment of the sails, the side force production and induced resistance due to side force at various combinations of forward speeds, leeway angles and heeling angles. New formulations for the relevant hydrodynamic forces as function of the hull geometry parameters have been derived to be able to deal with a larger variety of yacht hull shapes and appendage designs. During the past two years some results of this research have already been published. In the present paper an almost complete picture of the relevant expressions which may be used in a Velocity Prediction Program (VPP) will be presented.

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