Seakeeping Evaluation of a Tri-SWACH Based on CFD Calculations and Model Tests

2021 ◽  
Author(s):  
Gong Xiang ◽  
Raju Datla ◽  
Xianbo Xiang
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Three Dimensional ◽  
Primary Objective ◽  
Model Tests ◽  
Numerical Predictions ◽  
Seakeeping Performance ◽  
Stevens Institute ◽  
Transverse Stability ◽  
Institute Of Technology

AEGIR is a time-domain seakeeping CFD code that uses an advanced, high-order boundary element method (BEM) to solve the three-dimensional potential-flow and has been developed for several years. In this paper, the latest version of AEGIR is used to predict the seakeeping of the Tri-SWACH with and without side hulls in headsea regular waves respectively. The primary objective was to evaluate its accuracy of predicting seakeeping performance of the Tri-SWACH under regular headsea waves in AEGIR. A series of simulated time domain heave and pitch responses for Tri-SWACH with and without side hulls via AEGIR have been compared with corresponding model tests conducted in the high speed towing tank in Davidson Lab, Stevens Institute of Technology. A good agreement in terms of heave and pitch responses between AEGIR numerical predictions and experimental data shows the seakeeping prediction capability of AEGIR for Tri-SWACH Preliminary Design. Also, the simulated seakeeping of a Tri-SWACH is compared with a Tri-SWACH center hull. It is found that the effects of side hulls will increase the transverse stability of the Tri-SWACH without causing additional significant effect on the seakeeping performance of the Tri-SWACH.

Numerical Modeling of Dynamic Stability Events on a High Speed Catamaran

2010 ◽  
Author(s):  
Sean Kery ◽  
Michael Webster ◽  
Janelle Prange
Keyword(s):  
Numerical Modeling ◽  
Dynamic Response ◽  
Wave Field ◽  
Dynamic Stability ◽  
High Speed ◽  
Model Testing ◽  
Model Tests ◽  
Numerical Analyses ◽  
Ship Motions ◽  
Transverse Stability

A dynamic stability event— not to be confused with ordinary or damaged transverse stability—is a sudden and seldom occurring event that can result from an unusual dynamic response in some combinations of speed, heading, ship motions phase and wave field. This paper defines several dynamic stability events and describes a process developed to investigate them. The process involves model tests, numerical analyses, and a high speed catamaran test vessel. The strengths and weaknesses of model testing are compared to numerical analyses, and the overall validity of the results are discussed.

Ship Motion Computations Using a High Froude Number Time Domain Strip Theory

2006 ◽  
Vol 50 (01) ◽  
pp. 15-30
Author(s):  
D. S. Holloway ◽  
M. R. Davis
Keyword(s):  
Froude Number ◽  
Time Domain ◽  
High Speed ◽  
Equations Of Motion ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Strip Theory ◽  
Large Amplitude Motions ◽  
The Time Domain

High-speed strip theories are discussed, and a time domain formulation making use of a fixed reference frame for the two-dimensional fluid motion is described in detail. This, and classical (low-speed) strip theory, are compared with the experimental results of Wellicome et al. (1995) up to a Froude number of 0.8, as well as with our own test data for a semi-SWATH, demonstrating the marked improvement of the predictions of the former at high speeds, while the need to account for modest viscous effects at these speeds is also argued. A significant contribution to time domain computations is a method of stabilizing the integration of the ship's equations of motion, which are inherently unstable due to feedback from implicit added mass components of the hydrodynamic force. The time domain high-speed theory is recommended as a practical alternative to three-dimensional methods. It also facilitates the investigation of large-amplitude motions with stern or bow emergence and forms a simulation base for the investigation of ride control systems and local or global loads.

Seakeeping Analysis of a High-Speed Monohull With a Motion-Control Bow Hydrofoil

2004 ◽  
Vol 48 (02) ◽  
pp. 77-117 ◽  
Author(s):  
Paul D. Sclavounos ◽  
Henning Borgen
Keyword(s):  
Motion Control ◽  
High Speed ◽  
Three Dimensional ◽  
Control Device ◽  
Control Mechanisms ◽  
Hull Form ◽  
Active Motion ◽  
Seakeeping Performance ◽  
Seakeeping Analysis ◽  
Longitudinal Position

The seakeeping performance is studied of a foil-assisted high-speed monohull vessel using a state-of-the-art three-dimensional Rankine panel method. The vessel is equipped with a bow hydrofoil acting as a passive heave and pitch motion-control device in waves. The formulation of the seakeeping of ships equipped with lifting appendages is developed, and the mechanisms responsible for the reduction of the heave and pitch motions of high- speed vessels equipped with hydrofoils are studied. The sensitivity of the heave and pitch motions on the longitudinal position of the hydrofoil is studied. It is found that the most efficient location for the hydrofoil is at the ship bow leading to a 50% reduction of the root mean square values of the heave and pitch motions in a Joint North Sea Wave Project (JONSWAP) spectrum. Several extensions of the analysis of the present paper are discussed. They include the reduction of the roll motion of high-speed vessels, the design of optimal active motion-control mechanisms, and the coupling of the hull form and lifting appendage design for high-speed monohull vessels.

scholarly journals Model tests on resistance and seakeeping performance of wave-piercing high-speed vessel with spray rails

2016 ◽  
Vol 8 (5) ◽  
pp. 442-455 ◽  
Author(s):  
Jeonghwa Seo ◽  
Hak-Kyu Choi ◽  
Uh-Cheul Jeong ◽  
Dong Kun Lee ◽  
Shin Hyung Rhee ◽  
...  
Keyword(s):  
High Speed ◽  
Model Tests ◽  
Seakeeping Performance

An Optimization Study of TriSWACH Side-Hull Position for Minimum Resistance in Calm Water

2017 ◽  
Author(s):  
Yufei Ai ◽  
Yulin Zhao ◽  
Raju Datla
Keyword(s):  
Froude Number ◽  
Water Resistance ◽  
Hydrodynamic Characteristics ◽  
Hull Form ◽  
Optimization Study ◽  
Seakeeping Performance ◽  
Stevens Institute ◽  
Calm Water ◽  
Institute Of Technology ◽  
Minimum Resistance

TriSWACH is a promising novel hull form for its reduced resistance, larger deck area and good seakeeping performance. This paper aims to determine an optimal sidehull position for TriSWACH based on the minimum resistance in calm water. STAR-CCM+, a RANS-based commercial CFD tool and a potential flow code Michelet are compared in their calculations of resistance. Four different side-hull positions of the TriSWACH operated within Froude number from 0.1 to 0.5 with increment 0.05 are considered for the numerical simulations. The simulation results are further validated by the model tests performed in Stevens Institute of Technology Davidson Laboratory towing tank. The comparison shows that STAR-CCM+ RANS codes can predict TriSWACH’s hydrodynamic characteristics in calm water with high accuracy. Finally, TriSWACH's optimal side-hulls’ position was discussed based on calm water resistance within different Froude number ranges.

Some Considerations on the Reaction of Wind Upon Sails

1938 ◽  
Vol 42 (334) ◽  
pp. 867-871 ◽  
Author(s):  
J. T. C. Moore-Brabazon
Keyword(s):  
New Jersey ◽  
Model Tests ◽  
Towing Tank ◽  
Stevens Institute ◽  
Institute Of Technology ◽  
General Configuration ◽  
Sailing Boat

The study of the problems connected with a successful racing sailing boat, like Gaul, can be divided into three parts. There is first of all the general configuration of the hull upon which lately much study has been directed. Anybody interested in this should look up the article, “Model Tests of Sailing Yachts,” by Kenneth S. M. Davidson, Director, Experimental Towing Tank, Stevens Institute of Technology, New Jersey, appearing in the August issue of “The Rudder,” in which it will be noted model hulls are pulled through the tank at an angle of heel, and with an angle of drift.

Selecting a Keel Appendage for a Cruising Yacht From a Standard Keel Series

1979 ◽  
Author(s):  
Deborah W. Berman
Keyword(s):  
Aspect Ratio ◽  
Model Tests ◽  
Thickness Ratio ◽  
Model Data ◽  
Standard Series ◽  
Stevens Institute ◽  
Form Part ◽  
Institute Of Technology

The purpose of this paper is to describe the results of model tests for a series of three keels; two at constant draft; two at constant aspect ratio; all at constant taper ratio and thickness ratio. These keels form part of a standard series developed by Pierre De Saix at Davidson Laboratory, Stevens Institute of Technology in 1974 and originally tested on a 5.5 meter hull (1). The three keels were all tested on the model of a small cruising yacht over a range of heel angles, leeways and speeds. An analysis is made of the expanded model data and a comparison presented of the forces and moments operating on the deepest keel and the two keels of constant draft.

High Speed Friction Stir Welding: A Computational and Experimental Study

2005 ◽  
Author(s):  
Harsha Raikoty ◽  
Ikram Ahmed ◽  
George E. Talia
Keyword(s):  
Friction Stir Welding ◽  
Thermal Model ◽  
High Speed ◽  
Three Dimensional ◽  
Weld Line ◽  
Infrared Camera ◽  
Processing Conditions ◽  
Moving Heat Source ◽  
Friction Stir ◽  
Numerical Predictions

A three-dimensional numerical analysis of friction stir welding at high speed (HS-FSW) is presented here. The temperature distribution in the workpiece has been calculated for a number of processing conditions. The analysis adopts a thermal model based on the simple laws of friction. This model translates to having a moving heat source along the weld-line on the top surface of the workpieces. Results have been validated experimentally using an infrared camera as well as thermocouple measurements. By comparing actual welds performed on Aluminum 6061-T6 and the numerical predictions, it is observed that the appropriate range for the (maximum) surface temperatures for obtaining a sound weld is between 570°C and 530°C, and that these temperatures are achieved between spindle translation velocities of 125 mm/min and 250 mm/min, respectively.

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