Experimental and Numerical Investigation of the Wave-Induced Loads on a Deep-V Catamaran in Regular Waves

2013 ◽  
Author(s):  
Musa B. Bashir ◽  
Longbin Tao ◽  
Mehmet Atlar ◽  
Robert S. Dow
Keyword(s):  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
Proper Understanding ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Numerical Predictions ◽  
New Research ◽  
Wave Induced

This paper presents the results of towing tank tests carried out to predict the wave loads in regular wave conditions on a Deep-V hull form catamaran model. The experiments were carried out at the Newcastle University towing tank using a segmented model of the university’s new research vessel, “The Princess Royal”. The vessel is a twin hull with a Deep-V shape cross-section. The model, divided into two parts at the cross-deck level, was fitted with a 5-axis load cell at the position of the vessel’s centre of gravity in order to measure the motions response and wave loads due to the encountered waves. The longitudinal, side and vertical forces, along with the prying and yaw splitting moments were measured. The results obtained were further compared with those from numerical predictions carried out using a 3D panel method code based on potential flow theory that uses Green’s Function with the forward speed correction in the frequency domain. The results highlight reasonable correlations between the measurements and the predictions as well as the need for a proper understanding of the response of the multihull vessels to the wave-induced loads due to the non-linearity that have been observed in the experimental measurements of wave loads.

scholarly journals WAVE-INDUCED LOADS ON CROSS-DECK OF A WAVE-PIERCING TRIMARAN WITH DIFFERENT HULL FORMS OF OUTRIGGERS

Transport ◽  
2019 ◽  
Vol 34 (5) ◽  
pp. 559-568
Author(s):  
Abolfath Askarian Khoob ◽  
Mohammad Javad Ketabdari
Keyword(s):  
Potential Flow ◽  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Hull Form ◽  
High Speeds ◽  
Complex Structural ◽  
Hull Forms ◽  
Wave Induced ◽  
Study Offer

Trimaran has unique hull form with a rapidly growth in recent years due to its application as a mode of transports and naval vessels. Designing trimaran faces many technical challenges because of its complex structural outlines and high-speeds operation. This article investigates the influence of side hulls configuration (symmetric, inboard and outboard types) for wave loads on cross-deck of a trimaran ship when advancing at sea in regular waves. The computation of these hydrodynamic forces is carried out using MAESTRO-Wave 3D panel method code. This code is based on potential flow theory that uses Green’s function with the forward speed correction in the frequency domain. The results demonstrate that the outboard side hull form has the best performance on wave-induced load among three kinds of side hull forms. Furthermore, the results of this study offer more information for selecting the side hull form of the trimaran.

THE INFLUENCE OF CENTRE BOW LENGTH ON SLAMMING LOADS AND MOTIONS OF LARGE WAVE-PIERCING CATAMARANS

2021 ◽  
Vol 160 (A1) ◽  
Author(s):  
J R Shahraki ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Wave Height ◽  
Full Scale ◽  
Bending Moments ◽  
Regular Waves ◽  
Large Wave ◽  
Towing Tank ◽  
Segmented Model ◽  
Model Experiments ◽  
Slamming Load ◽  
Wave Induced

The effect of various centre bow lengths on the motions and wave-induced slamming loads on wave-piercing catamarans is investigated. A 2.5 m hydroelastic segmented model was tested with three different centre bow lengths and towed in regular waves in a towing tank. Measurements were made of the model motions, slam loads and vertical bending moments in the model demi-hulls. The model experiments were carried out for a test condition equivalent to a wave height of 2.68 m and a speed of 20 knots at full scale. Bow accelerations and vertical bending moments due to slamming showed significant changes with the change in centre bow, the longest centre bow having the highest wave-induced loads and accelerations. The increased volume of displaced water which is constrained beneath the bow archways is identified as the reason for this increase in the slamming load. In contrast it was found that the length of centre bow has a relatively small effect on the heave and pitch motions in slamming conditions.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

The Influences of Centre Bow Length on Slamming Loads and Motions of Large Wave-Piercing Catamarans

2018 ◽  
Vol Vol 160 (A1) ◽  
Author(s):  
J R Shahraki ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Wave Height ◽  
Full Scale ◽  
Bending Moments ◽  
Regular Waves ◽  
Large Wave ◽  
Towing Tank ◽  
Segmented Model ◽  
Model Experiments ◽  
Slamming Load ◽  
Wave Induced

The effect of various centre bow lengths on the motions and wave-induced slamming loads on wave-piercing catamarans is investigated. A 2.5 m hydroelastic segmented model was tested with three different centre bow lengths and towed in regular waves in a towing tank. Measurements were made of the model motions, slam loads and vertical bending moments in the model demi-hulls. The model experiments were carried out for a test condition equivalent to a wave height of 2.68 m and a speed of 20 knots at full scale. Bow accelerations and vertical bending moments due to slamming showed significant changes with the change in centre bow, the longest centre bow having the highest wave-induced loads and accelerations. The increased volume of displaced water which is constrained beneath the bow archways is identified as the reason for this increase in the slamming load. In contrast it was found that the length of centre bow has a relatively small effect on the heave and pitch motions in slamming conditions.

Hydrodynamic Performance of a Deep-Vee Hull Form Catamaran in Regular Waves

2011 ◽  
Author(s):  
Musa B. Bashir ◽  
Longbin Tao ◽  
Mehmet Atlar ◽  
Robert S. Dow
Keyword(s):  
National Physical Laboratory ◽  
Hydrodynamic Performance ◽  
Regular Waves ◽  
Hull Form ◽  
Towing Tank ◽  
Geometrical Properties ◽  
Physical Laboratory ◽  
Motion Measurements ◽  
Motion Characteristics ◽  
Hull Forms

This paper presents the results of experiments carried out to determine the motion/seakeeping behavior of a deep-vee hull form catamaran in regular sea condition. A deep-vee catamaran model for the Newcastle University’s new RV replacing the old RV Bernicia was used for the motion measurements. The experiments were performed in the university’s towing tank. The results obtained were validated using a 3D panel method in frequency domain. A comparison of these results with the motion characteristics of the NPL (National Physical Laboratory) round bilge hullform based catamaran of similar geometrical properties revealed that the deep-vee hull forms possess significantly better seakeeping capabilities than a round bilge hull form.

A Study of Dynamic Responses and Wave Loads on Ships by 3-D Green Function Method

2006 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Md. Kamruzzaman
Keyword(s):  
Green Function ◽  
Design Procedure ◽  
Ship Design ◽  
Dynamic Responses ◽  
Ship Motions ◽  
Wave Loads ◽  
Forward Speed ◽  
Regular Waves ◽  
Field Problem ◽  
Dynamic Wave

The dynamic wave loads are the most significant factor for the hull design of a ship. But experimental works for the motion responses of a ship and sea loads on her are expensive and time consuming for individual ship design. Therefore, the development of theoretical and numerical methods for predicting ship motions and dynamic loads on a ship in waves is very important for rational ship design procedure. In general, though 3-D Green function techniques with forward speed need long computation time, however it should be more accurate assumption of the flow field problem on an advancing ship in waves. Nowadays the availability of much faster computer makes the 3-D Green function techniques with forward speed more familiar than before. In this paper, numerical analyses on ship motions and wave loads are presented for ships with forward speed advancing in regular waves. 3-D Green function techniques have been used to carry out the numerical computations for the radiation problem and wave loads for a moving ship. Based on the 3–D linearized potential theory, dynamic wave loads have been computed of a bulk carrier in regular waves where experimental measurements are available. The computations are carried out for various heading angles between head sea and following sea and various ranges of frequencies. The results for motions, and vertical and horizontal bending moments are presented in this paper. Computed results are compared with the experimental data. The results calculated by the present method are found in fairly good agreement with the experimental results and those calculated by the other researchers. Using developed computer code, some parametric studies are also carried out for the ship design criteria and the discussions are made.

Improving the Panel-Free Method for the Prediction of Ship Motions and Wave Induced Loads

2017 ◽  
Author(s):  
Wei Qiu ◽  
Heather Peng ◽  
Junshi Wang ◽  
Shahriar Nizam
Keyword(s):  
Simple Algorithm ◽  
Design Stage ◽  
Ship Motions ◽  
Wave Loads ◽  
Forward Speed ◽  
Early Design Stage ◽  
B Splines ◽  
Frequency Domain Methods ◽  
Nurbs Surfaces ◽  
Wave Induced

Frequency-domain methods are proven efficient and reliable, especially for zero forward speed, in early design stage for the prediction of ship motions and wave-induced wave loads. There are still challenges for ships with forward-speed due to the inaccuracy in the computation of m-terms. In this paper, the panel-free method is further improved to predict motions and wave-induced loads on real ships with forward speeds. A simple algorithm has been developed to re-arrange the control points for Non-Uniform Rational B-Splines (NURBS) surfaces. This method led to reliable and accurate m-term computations and therefore improved ship motion and load predictions. Validation studies have been carried out for a hydroelastic model of a frigate. Computed motions and loads were compared with experimental data.

scholarly journals Test Studies of the Resistance and Seakeeping Performance of a Trimaran Planing Hull

2015 ◽  
Vol 22 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Weijia Ma ◽  
D. Hanbing Sun ◽  
D. Huawei Sun ◽  
D. Jin Zou ◽  
Jiayuan Zhuang
Keyword(s):  
Small Angle ◽  
Test Results ◽  
Regular Waves ◽  
Longitudinal Stability ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Air Jets ◽  
Seakeeping Performance ◽  
Calm Water ◽  
The Stability

Abstract Towing tank tests in calm water were performed on a trimaran planing hull to verify its navigational properties with different displacements and centres of gravity, as well as to assess the effects of air jets and bilge keels on the hull’s planing capabilities, and to increase the longitudinal stability of the hull. Hydrostatic roll tests, zero speed tests, and sea trials in the presence of regular waves were conducted to investigate the hull’s seakeeping ability. The test results indicate that the influence of the location of the centre of gravity on the hull resistance is similar to that of a normal trimaran planing hull; namely, moving the centre of gravity backward will reduce the resistance but lower the stability. Bilge keels improve the longitudinal stability but slightly affect the resistance, and the presence of air jets in the hull’s channels decreases the trim angle and increases heaving but has little effect on the resistance. Frequent small-angle rolling occurs in waves. The heaving and pitching motions peak at the encounter frequency of , and the peaks increase with velocity and move towards greater encounter frequencies. When the encounter frequency exceeds, the hull motion decreases, which leads to changes in the navigation speed and frequency.

Study on vertical motion reduction of a trimaran based on collaborative controlled appendages

2020 ◽  
Vol 17 (6) ◽  
pp. 172988142097677
Author(s):  
Zhilin Liu ◽  
Linhe Zheng ◽  
Guosheng Li ◽  
Shouzheng Yuan ◽  
Songbai Yang
Keyword(s):  
Experimental Study ◽  
Vertical Motion ◽  
Model Tests ◽  
Wave Period ◽  
Regular Waves ◽  
Towing Tank ◽  
Vertical Stability ◽  
Stabilization Control ◽  
Stability Performance

In recent years, the trimaran as a novel ship has been greatly developed. The subsequent large vertical motion needs to be studied and resolved. In this article, an experimental study for a trimaran vertical stabilization control is carried out. Three modes including the bare trimaran (the trimaran without appendages, the trimaran with fixed appendages, and the trimaran with controlled appendages) are performed through model tests in a towing tank. The model tests are performed in regular waves. The range of wave period is 2.0–4.0 s, and the speed of the carriage is 2.93 and 6.51 m/s. The results of the three modes show the fixed appendages and the actively controlled appendages are all effective for the vertical motion reduction of the trimaran. Moreover, the controlled appendages are more effective for the vertical stability performance of the trimaran.

scholarly journals ‘Mammoth Vessels and Coriolis Force’

1971 ◽  
Vol 24 (2) ◽  
pp. 252-253
Author(s):  
G. R. G. Lewison
Keyword(s):  
Northern Hemisphere ◽  
Coriolis Force ◽  
Forward Speed ◽  
Centre Of Pressure ◽  
Drift Angle ◽  
Centre Of Gravity ◽  
Resistive Forces ◽  
Yaw Angle

Mr. Anneveld's paper (24, 50) would have us believe that the effects of coriolis force on a ship may become appreciable as ship size increases. It is true that the drift angle does increase as the ship's size increases, because the coriolis force given by equation (1) increases as (length)3·5 and the resistive forces increase as (length)3 (on the assumption of geometrically similar ships and Froude scaling). However there is a fundamental flaw in his argument because equation (2) only applies to a vessel with zero forward speed. Moreover the effect of coriolis drift will also be to induce a yaw angle on the ship (because the centre of pressure is forward of the centre of gravity, where the coriolis force may be assumed to act) and this will automatically cause the helmsman or autopilot to apply starboard rudder in the northern hemisphere. This will immediately produce a force on the ship in the port direction, i.e. opposing coriolis force.

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