HYDRODYNAMIC HULL FORM DESIGN SPACE EXPLORATION OF LARGE MEDIUM-SPEED CATAMARANS USING FULL-SCALE CFD

2021 ◽  
Vol 157 (A3) ◽  
Author(s):  
M Haase ◽  
J R Binns ◽  
N Bose ◽  
G Davidson ◽  
G Thomas ◽  
...  
Keyword(s):  
Design Space Exploration ◽  
Design Space ◽  
Free Surface Flow ◽  
Design Guidelines ◽  
Surface Flow ◽  
Full Scale ◽  
Efficient Operation ◽  
Medium Speed ◽  
Wide Range ◽  
Form Design

Large medium-speed catamarans are a new class of vessel currently under development as fuel-efficient ferries for sustainable fast sea transportation. Appropriate data to derive design guidelines for such vessels are not available and therefore a wide range of demihull slenderness ratios were studied to investigate the design space for fuel-efficient operation. Computational fluid dynamics for viscous free-surface flow simulations were utilised to investigate resistance properties of different catamaran configurations having a similar deadweight at light displacement, but with lengths ranging from 110 m to 190 m. The simulations were conducted at full-scale Reynolds numbers (log(Re) = 8.9 – 9.6) and Froude numbers ranged from Fr = 0.25 to 0.49. Hulls of 130 m and below had high transport efficiency below 26 knots and in light loading conditions while hulls of 150 m and 170 m showed benefits for heavier displacement cases and speeds up to 35 knots. Furthermore, the study concluded that the lowest drag was achieved with demihull slenderness ratios between 11 and 13.

Hydrodynamic Hull form Design Space Exploration of Large Medium-Speed Catamarans using Full-Scale CFD

2015 ◽  
Vol 157 (A3) ◽  
pp. 161-174
Keyword(s):  
Design Space Exploration ◽  
Design Space ◽  
Free Surface Flow ◽  
Design Guidelines ◽  
Surface Flow ◽  
Full Scale ◽  
Efficient Operation ◽  
Medium Speed ◽  
Wide Range ◽  
Form Design

Large medium-speed catamarans are a new class of vessel currently under development as fuel-efficient ferries for sustainable fast sea transportation. Appropriate data to derive design guidelines for such vessels are not available and therefore a wide range of demihull slenderness ratios were studied to investigate the design space for fuel-efficient operation. Computational fluid dynamics for viscous free-surface flow simulations were utilised to investigate resistance properties of different catamaran configurations having a similar deadweight at light displacement, but with lengths ranging from 110 m to 190 m. The simulations were conducted at full-scale Reynolds numbers (log(Re) = 8.9 – 9.6) and Froude numbers ranged from Fr = 0.25 to 0.49. Hulls of 130 m and below had high transport efficiency below 26 knots and in light loading conditions while hulls of 150 m and 170 m showed benefits for heavier displacement cases and speeds up to 35 knots. Furthermore, the study concluded that the lowest drag was achieved with demihull slenderness ratios between 11 and 13.

scholarly journals Turbine thermomechanical modelling during excessive axial movement and overspeed

2019 ◽  
Vol 123 (1260) ◽  
pp. 248-264
Author(s):  
I. Eryilmaz ◽  
V. Pachidis
Keyword(s):  
Finite Element ◽  
Design Space Exploration ◽  
Design Space ◽  
Design Guidelines ◽  
Dislocation Rate ◽  
Frictional Torque ◽  
Turbine Wheel ◽  
Axial Movement ◽  
Free Running ◽  
Shaft Failure

ABSTRACTThis manuscript discusses the numerical (finite element) and analytical modelling of structural interactions between gas turbine components in case of excessive axial movement and overspeed. Excessive axial movement, which may occur after a shaft failure, results in contact between rotating and static turbine components under high forces. These forces create friction which can act as a counter torque, potentially retarding the ‘free-rotating’ components. The study is based on a shaft failure scenario of a ‘three-shaft’, high ‘bypass’ ratio, civil ‘large-fan’ engine. Coupled analytical performance and friction methods are used as stand-alone tools to investigate the effect of rubbing between rotating and stationary components. The method is supported by ‘high-fidelity’, ‘three-dimensional’, thermomechanical finite element simulations using LS-DYNA software. The novelty of the work reported herein lies in the development of a generalised modelling approach that can produce useful engine design guidelines to minimise the terminal speed of a free running turbine after an unlocated shaft failure. The study demonstrates the advantage of using a fast analytical formulation in a design space exploration, after verifying the analytical model against finite element simulation results. The radius and the area of a stationary seal platform in the turbine assembly are changed systematically and the design space is explored in terms of turbine acceleration, turbine dislocation rate and stationary component mass. The radius of the friction interface increases due to the increasing radius of the nozzle guide vane flow path and stationary seal platform. This increases the frictional torque generated at the interface. It was found that if the axial dislocation rate of the free running turbine wheel is high, the resulting friction torque becomes more effective as an overspeed prevention mechanism. Reduced contact area results in a higher axial dislocation rate and this condition leads to a design compromise between available friction capacity, during shaft failure contact and seal platform structural integrity.

scholarly journals A Coupled Model for Wave Run-up Simulation

2018 ◽  
Author(s):  
Iryanto ◽  
Sri Redjeki Pudjaprasetya
Keyword(s):  
Euler Equations ◽  
Coupled Model ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Flow Problems ◽  
Wide Range ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Run Up ◽  
Sloping Beach

Simplified models like the shallow water equations (SWE) are commonly adopted for describing a wide range of free surface flow problems, like flows in rivers,lakes, estuaries, or coastal areas. In the literature, numerical methods for the SWE are mostly mesh-based. However, this macroscopic approach is unable to accurately represent the complexity of flows near coastlines, where waves nearly break. This fact prompted the idea of coupling the mesh-based SWE model with a meshless particlemethod for solving the Euler equations. In a previous paper, a method to couple the staggered scheme SWE and the smoothed particle hydrodynamics (SPH) Euler equations was developed and discussed. In this article, this coupled model is used for simulating solitary wave run-up on a sloping beach. The results show strong agreement with the experimental data of Synolakis. Simulations of wave overtopping over aseawall were also performed.

scholarly journals Implementation of integrated design space exploration of scheduling, allocation and binding in high level synthesis using multi structure genetic algorithm

2021 ◽  
Author(s):  
Michael Gebremariam
Keyword(s):  
Genetic Algorithm ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Integrated Design ◽  
High Level Synthesis ◽  
C Language ◽  
Low Level ◽  
Wide Range ◽  
High Level

The objective of this project is to develop a software tool which assists in comparison of a work known as "M-GenESys: Multi Structure Genetic Algorithm based Design Space Exploration System for Integrated Scheduling, Allocation and Binding in High Level Synthesis" with another well established GA approach known as "A Generic Algorithm for the Design Space Exploration of Data paths During High-Level Synthesis". Two sets of software are developed based on both approaches using Microsoft Visual 2005 C# language. The C# language is an object-oriented language that is aimed at enabling programmers to quickly develop a wide range of applications on the Microsoft .NET platform. The goal of C# and the .NET platform is to shorten development time by freeing the developer from worrying about several low level plumbing issues such as memory equipment, type safety issues, building low level libraries, array bound checking, etc., thus allowing developers to actually spend their time and energy working on the application and business logic.

Full-Scale Simulation-Based Hull Form Design for Large Medium-Speed Catamarans with High Fuel Efficiency

2015 ◽  
Author(s):  
Max Haase ◽  
Gary Davidson ◽  
Stuart Friezer ◽  
Jonathan Binns ◽  
Giles Thomas ◽  
...  
Keyword(s):  
Drag Force ◽  
Numerical Study ◽  
Fuel Efficiency ◽  
Full Scale ◽  
Hull Form ◽  
High Fuel Efficiency ◽  
Medium Speed ◽  
Simulation Based ◽  
Form Design ◽  
Hull Form Design

This paper reports on a numerical study to obtain the full-scale drag force for large catamarans of 110 m to 190 m in length at medium speeds of Froude numbers between 0.25 and 0.49, which comprises vessel speeds from 16 to 41 knots. The paper concludes with appropriate values of slenderness ratios and transom immersion for the lowest total resistance at different Froude numbers, and appropriate hull lengths to achieve highest possible fuel efficiency for different drafts at speeds between 24 and 33 knots. These slenderness ratios, for lowest drag force, were determined at different Froude numbers of 0.25, 0.37 and 0.45.

Free Surface Flow Past Ships in Shallow Water

2002 ◽  
Author(s):  
A. Ganguly ◽  
V. Shigunov ◽  
O. Turan
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Near Field ◽  
Free Surface Flow ◽  
Steady State Solution ◽  
Surface Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Medium Speed ◽  
Measured Resistance

A finite volume method with a multiphase type free surface description is employed to calculate the flow around ships in shallow and restricted channels. The flows at critical and supercritical depth Froude numbers (Fnd = 1.0 and Fnd = 1.18) are calculated for Series–60 monohull and a medium speed catamaran. A steady state solution for Reynolds-averaged Navier-Stokes equations with a k-ε turbulence model is obtained by time marching. Computed wave profiles are in good agreement with model tests in the near field of the ship. The computed and measured resistance agree fairly well.

Introduction des conditions réelles de débit aux limites d'un modèle hydrodynamique

1995 ◽  
Vol 22 (6) ◽  
pp. 1133-1142
Author(s):  
Jean-Loup Robert ◽  
Mohammad Hossein Hamedi
Keyword(s):  
Boundary Conditions ◽  
Free Surface Flow ◽  
Integral Form ◽  
Surface Flow ◽  
Design Tool ◽  
Experimental Comparison ◽  
Flow Modelling ◽  
Wide Range ◽  
Set Up ◽  
High Level

The main goal of this paper is to present a technique to improve the specification of discharge at the open boundaries of a hydrodynamic numerical model. Generally, two dimensional models need boundary conditions using imposed values of water level and (or) velocity components. Although these conditions are satisfactory in most situations, they are not sufficient for open channel flow modelling, in which the discharge is set up according to the upstream hydraulic head. The integral form, needed by finite element modelling, is useful to generate explicit boundary terms that, adequately used, allow the introduction of discharge boundary conditions at open borders of the application domain. The theoretical aspects of this approach are first detailed and, to check the validity of the development and to evaluate the reliability of the model as a design tool, the numerical results are compared with observations on an experimental installation. The results allow to conclude that the proposed model offer a wide range of applications and a high level of accuracy and that it can be considered as a useful aid for hydraulic design. Key words: hydrodynamics, free surface flow, modelling, finite elements, discharge law, boundary conditions, numerical-experimental comparison.

scholarly journals GPU implementation of restricted Boltzmann machines with application to view classification in sports videos

2021 ◽  
Author(s):  
Andreas Fred Bernitzke
Keyword(s):  
Genetic Algorithm ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
High Level Synthesis ◽  
Restricted Boltzmann Machines ◽  
C Language ◽  
Low Level ◽  
Wide Range ◽  
High Level

The objective of this project is to develop a software tool which assists in comparison of a work known as "M-GenESys: Multi Structure Genetic Algorithm based Design Space Exploration System for Integrated Scheduling, Allocation and Binding in High Level Synthesis" with another well established GA approach known as "A Genetic Algorithm for the Design Space Exploration of Data paths During High-Level Synthesis". Two sets of Software are developed based on both approaches using Microsoft visual 2005,C# language. The C# language is an object-oriented language that is aimed at enabling programmers to quickly develop a wide range of applications on the Microsoft .NET platform. The goal of C# and the .NET platform is to shorten development time by freeing the developer from worrying about several low level plumbing issues such as memory management, type safety issues, building low level libraries, array bounds checking, etc. thus allowing developers to actually spend their time and energy working on the application and business logic.

scholarly journals Implementation of integrated design space exploration of scheduling, allocation and binding in high level synthesis using multi structure genetic algorithm

2021 ◽  
Author(s):  
Michael Gebremariam
Keyword(s):  
Genetic Algorithm ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Integrated Design ◽  
High Level Synthesis ◽  
C Language ◽  
Low Level ◽  
Wide Range ◽  
High Level

The objective of this project is to develop a software tool which assists in comparison of a work known as "M-GenESys: Multi Structure Genetic Algorithm based Design Space Exploration System for Integrated Scheduling, Allocation and Binding in High Level Synthesis" with another well established GA approach known as "A Generic Algorithm for the Design Space Exploration of Data paths During High-Level Synthesis". Two sets of software are developed based on both approaches using Microsoft Visual 2005 C# language. The C# language is an object-oriented language that is aimed at enabling programmers to quickly develop a wide range of applications on the Microsoft .NET platform. The goal of C# and the .NET platform is to shorten development time by freeing the developer from worrying about several low level plumbing issues such as memory equipment, type safety issues, building low level libraries, array bound checking, etc., thus allowing developers to actually spend their time and energy working on the application and business logic.

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