Experimental Results for Pitch Damping in Speed and Wave for a Surface Effect Ship with Split Air Cushion

2020 ◽  
Author(s):  
Vahid Hassani ◽  
Oyvind Auestad ◽  
Marco Nataletti
Keyword(s):  
Surface Effect ◽  
Experimental Results ◽  
Surface Effect Ship ◽  
Air Cushion ◽  
Pitch Damping

Radiation Hydrodynamics of a Surface Effect Ship

2013 ◽  
Author(s):  
Palaniswamy Ananthakrishnan
Keyword(s):  
Free Surface ◽  
Large Amplitude ◽  
Small Amplitude ◽  
Stokes Equations ◽  
Surface Effect ◽  
Wave Radiation ◽  
Absolute Pressure ◽  
Radiation Hydrodynamics ◽  
Surface Effect Ship ◽  
Air Cushion

The radiation hydrodynamics of a heaving surface effect ship (SES) is examined including the effect of air compressibility on the hydrodynamic forces and surface waves. Of particular focus of the study has been on determining the nonlinear viscous and air compressibility effects at natural frequencies corresponding to the piston and sloshing wave modes between the hulls and at the natural frequency corresponding to the heave motion of a surface effect ship with the restoring force dominated by the compressibility of the air cushion. In the present paper, the air cushion pressure is assumed to be uniform with its variation due to change of volume modeled using the adiabatic gas law pVγ = constant, where p denotes the absolute pressure of the air, V the air volume bounded by the side hulls, the free surface and the wet deck, and γ the ratio of specific heats Cp/Cv which is about 1.4 for air. The incompressible Navier-Stokes equations governing the nonlinear viscous wave-air-body interaction problem is solved in the time domain using a finite-difference method based on boundary fitted coordinates. New results presented in this paper show that air cushion compressibility affects the generation of waves and wave radiation forces significantly even at small amplitude of hull motion. As already well known, the free surface nonlinearity due to hull motion is significant for large amplitude of oscillation. At small amplitude of body oscillation, significant nonlinearity can be caused by air compressibility resulting in the generation of higher harmonic waves and forces. The results also highlight the significance of viscosity and flow separation, in conjunction with air compressibility, in the case of large amplitude hull motion with a small draft.

Comparison of Single and Overset Grid Techniques for CFD Simulations of a Surface Effect Ship

2014 ◽  
Author(s):  
Colton G. Clark ◽  
David G. Lyons ◽  
Wayne L. Neu
Keyword(s):  
Free Surface ◽  
Surface Effect ◽  
The Body ◽  
Computational Domain ◽  
Overset Grid ◽  
Hexahedral Mesh ◽  
Surface Effect Ship ◽  
Mesh Resolution ◽  
Refined Meshes ◽  
Air Cushion

Overset, or Chimera meshes are used to discretize the governing equations within a computational domain using multiple meshes that overlap in an arbitrary manner. The overset mesh technique is most applicable to problems dealing with multiple or moving bodies. In order to extend existing full craft CFD (RANS) simulations of a surface effect ship (SES) into shallow water and maneuvering cases, an overset mesh is needed. Deep water simulations were carried out using both single and overset grid techniques for evaluation of the overset grid application. The single grid technique applies a hexahedral mesh to the fluid domain and SES geometry. An adequate mesh resolution was determined by performing a grid convergence study on a series of systematically refined meshes. An overset mesh of the same resolution was then constructed and was fixed to the body. Drag and pitch results are compared among the two simulations. Free surface elevations around the craft and under the air cushion for simulations with the single and overset meshes are compared. Steady-state simulations using the overset mesh and the single mesh show general similarities in drag, pitch, and free surface elevations.

scholarly journals Roll damping of a surface effect ship with split air cushion

2018 ◽  
Vol 51 (29) ◽  
pp. 450-456
Author(s):  
Jonas Tønnessen ◽  
Håkon E. Bryn ◽  
Jan T. Gravdahl ◽  
Vahid Hassani ◽  
Øyvind F. Auestad
Keyword(s):  
Surface Effect ◽  
Roll Damping ◽  
Surface Effect Ship ◽  
Air Cushion

Air Cushion Vehicles and Surface Effect Ships for Great Lakes and Great Rivers Transportation

1990 ◽  
Vol 27 (06) ◽  
pp. 337-355
Author(s):  
John L. Allison
Keyword(s):  
Great Lakes ◽  
Surface Effect ◽  
Coast Guard ◽  
Rapid Expansion ◽  
Short Paper ◽  
Surface Effect Ship ◽  
Present Design ◽  
Air Cushion ◽  
Hull Forms ◽  
The U.S

A brief introduction to air cushion vehicle (ACV) and surface effect ship (SES) technology is presented, with past and present examples, to show that this technology may now be considered mature. Applicability of ACVs and SESs to transportation on the Great Lakes and rivers of Canada and the U.S. is discussed, with some emphasis on year-round service in the regions affected by ice. An indication of present design capabilities is provided with some examples of application to typical sets of requirements. Future developments are outlined in the light of the rapid expansion of air-supported ferry operation in other parts of the world, and military and Coast Guard applications in the U.S. and Canada. Some data on acquisition and operating costs are presented in comparison with those for other hull forms, with information on the type of technical and port support required for ACV and SES operation. Numerous references are provided to enable the reader to pursue the topics discussed in greater detail than is possible in a short paper.

Finite Element Contact/Impact Modeling Capability of Complex Surface Effect Ship Dynamics: Preliminary Assessment

2013 ◽  
Author(s):  
Ravi Challa ◽  
David Newborn ◽  
Solomon Yim
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Numerical Simulations ◽  
Water Surface ◽  
Large Scale ◽  
Surface Effect ◽  
Numerical Models ◽  
Channel Water ◽  
Surface Effect Ship ◽  
Air Cushion

Experimental tests were conducted on a large scale captive Surface Effect Ship (SES) specimen at the US Navy’s Large Cavitation Channel (LCC) to primarily determine the mechanics of bow finger seal motions. In this paper, preliminary qualitative comparisons between the experimental and numerical simulations comprised of test dependent variables such as spatially distributed channel water elevation, channel water speed and air-cushion pressure are presented. A surface effect ship is an air-cushion supported vessel with two side hulls and fore and aft flexible seals. The side hulls of the SES along with the wet deck, seals and the fluid-water surface constitute the boundary of the air-cushion. An evaluation of the predictive capabilities of the existing technology of a state-of-the-art nonlinear multi-physics finite element code (LS-DYNA) with its arbitrary Lagrangian Eulerian (ALE) technique in modeling the coupled fluid-structure interaction (FSI) behavior of the boundary of a SES with the water surface is studied. The predictive capability of the code to model a single stern seal deployment, a single seal impacting a rigid flat surface, multiple seals impacting a water free surface and the centerline profile of multiple stern seal deployment between two rigid surfaces were verified. Simple numerical models for a five-finger bow seal with partial submergence in uniform current have been developed. Additional features including the mechanism to pressurize the air cushion chamber were included. Preliminary finite element (FE) simulation results show that the robust contact and impact algorithm is shown to capture the physics of the complex flexible body FSI problem well. In view of the good qualitative comparison between the experimental and numerical simulations, the ALE feature is being employed for studying the complex flexible structural mechanics including bow and stern seal motions interacting with air cushion and free-surface hydrodynamics.

Multihull and Surface-Effect Ship Configuration Design: A Framework for Powering Minimization

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ronald W. Yeung ◽  
Hui Wan
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Early Stage ◽  
Base Line ◽  
Total Displacement ◽  
Surface Effect Ship ◽  
Linearized Theory ◽  
Air Cushion ◽  
New Formula ◽  
Analytical Expressions

The powering issue of a high-speed marine vehicle with multihulls and air-cushion support is addressed, since there is an often need to quickly evaluate the effects of several configuration parameters in the early stage of the design. For component hulls with given geometry, the parameters considered include the relative locations of individual hulls and the relative volumetric ratios. Within the realm of linearized theory, an interference-resistance expression for hull-to-hull interaction is first reviewed, and then a new formula for hull-and-pressure distribution interference is derived. Each of these analytical expressions is expressed in terms of the Fourier signatures or Kochin functions of the interacting component hulls, with the separation, stagger, and speed as explicit parameters. Based on this framework, an example is given for assessing the powering performance of a catamaran (dihull) as opposed to a tetrahull system. Also examined is the wave resistance of a surface-effect ship of varying cushion support in comparison with that of a base line catamaran, subject to the constraint of constant total displacement.

scholarly journals Surface Effect Ship with Four Air Cushions Part II: Roll and Pitch Damping

2019 ◽  
Vol 52 (21) ◽  
pp. 134-139 ◽  
Author(s):  
Ola M. Haukeland ◽  
Vahid Hassani ◽  
Øyvind Auestad
Keyword(s):  
Surface Effect ◽  
Surface Effect Ship ◽  
Pitch Damping

Silica Nanochannel Surface Effect on Monosaccharide Transport

2010 ◽  
Author(s):  
Arturas Ziemys ◽  
Alessandro Grattoni ◽  
Jaskaran Gill ◽  
Mauro Ferrari
Keyword(s):  
Molecular Dynamics ◽  
Molecular Modeling ◽  
Surface Effect ◽  
Glucose Solution ◽  
Effective Diffusivity ◽  
Experimental Methods ◽  
Experimental Results ◽  
Monosaccharide Transport

The interface of silica nanochannel of 10 nm was studied by molecular modeling and experimental methods. Molecular Dynamics study on glucose solution revealed that 2–3 nm of interface solution to silica walls has reduced glucose diffusivity. That reduction affects the effective diffusivity of glucose in silica nanochannel. Experimental results show Fickian-like release of glucose through 13 nm nanochannel. Molecular modeling and experimental results suggest that glucose is not sufficiently confined to possess non-Fickian behavior.

Large Surface Effect Ship Size Limits

2013 ◽  
Vol 29 (02) ◽  
pp. 84-91
Author(s):  
Stefanos Koullias ◽  
Santiago Balestrini Robinson ◽  
Dimitri N. Mavris
Keyword(s):  
Historical Data ◽  
Surface Effect ◽  
Advanced Materials ◽  
Complex Structures ◽  
First Principle ◽  
Simplified Models ◽  
Surface Effect Ship ◽  
Size Limits ◽  
Technology Level ◽  
Insight Into

The purpose of this study is to obtain insight into surface effect ship (SES) endurance without reliance on historical data as a function of geometry, displacement, and technology level. First-principle models of the resistance, structures, and propulsion system are developed and integrated to predict large SES endurance and to suggest the directions that future large SESs will take. It is found that large SESs are dominated by structural weight, which indicates the need for advanced materials and complex structures, and that advanced propulsion cycles can increase endurance by up to 33%. SES endurance is shown to be a nonlinear discontinuous function of geometry, displacement, and technology level that cannot be predicted by simplified models or assumptions.

Optimum Structural Design of High-Speed Surface Effect Ships Built of Composite Materials

2003 ◽  
Vol 40 (01) ◽  
pp. 42-48
Author(s):  
Chang Doo Jang ◽  
Ho Kyung Kim ◽  
Ha Cheol Song
Keyword(s):  
Composite Materials ◽  
Computer Program ◽  
Structural Design ◽  
High Speed ◽  
Surface Effect ◽  
Minimum Weight ◽  
Original Design ◽  
Optimum Structural Design ◽  
Surface Effect Ship ◽  
Speed Performance

A surface effect ship is known to be comparable to a high-speed ship. For the structural design of surface effect ships, advanced design methods are needed which can reflect the various loading conditions different from those of conventional ships. Also, minimum weight design is essential because hull weight significantly affects the lift, thrust powering and high-speed performance. This paper presents the procedure of optimum structural design and a computer program to minimize the hull weight of surface effect ships built of composite materials. By using the developed computer program, the optimum structural designs for three types of surface effect ships—built of sandwich plate only, stiffened single skin plate only, and both plates—are carried out and the efficiency of each type is investigated in terms of weight. The computer program, developed herein, successfully reduced the hull weight of surface effect ships by 15–30% compared with the original design. Numerical results of optimum structural designs are presented and discussed.

Sign in / Sign up

Export Citation Format

Share Document