Wave slamming loads on wave-piercer catamarans operating at high-speed determined by hydro-elastic segmented model experiments

2013 ◽  
Vol 33 ◽  
pp. 120-142 ◽  
Author(s):  
J. Lavroff ◽  
M.R. Davis ◽  
D.S. Holloway ◽  
G. Thomas
Keyword(s):  
High Speed ◽  
Segmented Model ◽  
Model Experiments ◽  
Wave Slamming

DETERMINATION OF WAVE SLAMMING LOADS ON HIGH-SPEED CATAMARANS BY HYDROELASTIC SEGMENTED MODEL EXPERIMENTS

2021 ◽  
Vol 153 (A3) ◽  
Author(s):  
J Lavroff ◽  
M R Davis ◽  
D S Holloway ◽  
G Thomas
Keyword(s):  
Relative Motion ◽  
High Speed ◽  
Wave Profile ◽  
Full Scale ◽  
Bending Moments ◽  
Towing Tank ◽  
Segmented Model ◽  
Wave Slamming ◽  
Dynamic Wave

A 2.5m hydroelastic segmented catamaran model has been developed based on the 112m INCAT wave-piercer catamaran to simulate the vibration response during the measurement of dynamic slam loads in head seas. Towing tank tests were performed in regular seas to measure the dynamic slam loads acting on the centre bow and vertical bending moments acting in the demihulls of the catamaran model as a function of wave frequency and wave height to establish the operational loads acting on the full-scale 112m INCAT catamaran vessel. Peak slam forces measured on the bow of the model are found to approach the weight of the model, this being similar to the findings of full-scale vessel trials. A review of the motions of the hydroelastic segmented catamaran model found that the heave and pitch motions give a good indication of slamming severity in terms of the dimensionless heave and pitch accelerations. The dynamic wave slam forces are closely related to the relative motion between the bow and the incident wave profile.

Joint High Speed Sealift (JHSS) Segmented Model Test Data Analysis and Validation of Numerical Simulations

2012 ◽  
Author(s):  
Dominic Piro ◽  
Kyle A. Brucker ◽  
Thomas T. O'Shea ◽  
Donald Wyatt ◽  
Douglas Dommermuth ◽  
...  
Keyword(s):  
Data Analysis ◽  
Numerical Simulations ◽  
Test Data ◽  
Model Test ◽  
High Speed ◽  
Segmented Model

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 Research on the Surf-Riding Region for High Speed Vessels

2015 ◽  
Author(s):  
Atsuo Maki ◽  
Yoshiki Miyauchi
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Safety Assessment ◽  
Estimation Methods ◽  
Model Experiments ◽  
Size Limitation ◽  
Analytical Estimation ◽  
Free Running ◽  
Surface Combatant ◽  
Surf Riding

It is well known that surf-riding phenomenon is the prerequisite of the broaching-to in following and quartering conditions. For the safety assessment of the fast vessel such as surface combatant sand patrol crafts, the estimation of the surf-riding condition is important. Therefore, so far several experimental efforts have been made. However, in these previous researches, the free running model experiments in high speed region, i.e.up to Froude number of 0.6 or 0.7, have not been conducted because of tank size limitation. As shown in this paper, there are occurrence and disappearance boundaries of surf-riding in lower and faster region, respectively. In our study, free running model experiments are carried out in high speed region, and then both boundaries are experimentally obtained. By using obtained results, the analytical estimation methods proposed by the authors can be well validated. Furthermore, the free running model experiments in irregular seas are also conducted. Then, surf-riding phenomenon in irregular seas is also discussed.

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.

Prospects for Very-High-Speed Hydrofoils

1975 ◽  
Vol 12 (04) ◽  
pp. 367-377
Author(s):  
A. C. Conolly
Keyword(s):  
Water Surface ◽  
High Speed ◽  
Angle Of Attack ◽  
Free Water ◽  
Open Ocean ◽  
Operating Condition ◽  
Model Experiments ◽  
Geometry Model ◽  
Present Generation ◽  
Very High

Severe hydrodynamic problems remain to be solved before hydrofoils can be designed to operate on the open ocean at speeds between 50 and 80 knots. These problems stem from two sources, cavitation and the free-water surface, complicated by the action of waves. Recently, a natural air venting phenomenon has been investigated which shows promise of being a very satisfactory mode for the operation of highspeed hydrofoils up to speeds at least as high as 80 knots. "Hyperventilation" is the complete breaking open to the atmosphere of a vapor or partially air-filled cavity, giving rise to an underwater planing condition. What was previously thought of as a transient, extremely shallow submergence phenomenon has been shown to be a stable and predictable operating condition with a wide "window" encompassing speed, depth, angle of attack, foil section, and planform geometry. Model experiments also showed that the discovery explains a problem that has been encountered with present-generation subcavitating hydrofoil boats; that is, if a non-surface-piercing foil broaches the water surface and then reenters, it fails to pick up lift immediately and the hull consequently impacts the water heavily.

The Finite Element Analysis of the Floor Damper of High Speed Train

2015 ◽  
Vol 740 ◽  
pp. 142-145
Author(s):  
Dong Zhe Wang ◽  
Jian Min Ge ◽  
Xian Kui Zeng ◽  
Zong Ting Zhang ◽  
Chong Lv
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Physical Model ◽  
Correction Factor ◽  
High Speed ◽  
Vertical Deformation ◽  
High Speed Train ◽  
Element Analysis ◽  
Model Experiments ◽  
The Finite Element Analysis

In this paper, based on the honeycomb floor damper of high-speed train, the finite element analysis was carried out on the floor damper, and we compared the experimental results with the physical model experiments. The results show that: when correction factor γ = 0.5, there is the minimum incremental error of vertical deformation, and the value of the damper parameters is the best at this time.

scholarly journals THE EXPERIMENTAL METHOD AND CFD STUDY OF THE BARE HULL FORM OF UNDERWATER VEHICLE AT NEAR SURFACE CONDITION

2021 ◽  
Vol 11 (1) ◽  
pp. 24-33
Author(s):  
Thu Han Tun ◽  
Ye Thet Htun
Keyword(s):  
High Speed ◽  
Surface Condition ◽  
Underwater Vehicle ◽  
Hull Form ◽  
Near Surface ◽  
Towing Tank ◽  
Model Experiments ◽  
Friction Component ◽  
High Froude Number ◽  
Towing Tank Test

Hull form selection, resistance and powering are important in designing underwater vehicle. An underwater vehicle bare hull form is based on the five parameters due to the interaction between the propeller and the hull. When they are running on the surface condition, there will be problems likely as surface vessel, but the main hull of the underwater vehicle is below the waterline with low freeboard. The underwater vehicles are operating with high speed at a high Froude Number. Therefore, the wave making component becomes important in surface resistance. The wave making resistance of the underwater vehicle model at surface condition is analyzed by using CFD tools. Friction component of resistance is calculated by using ITTC’57 correlation line. The flow around the ship’s hull is complicated, so that model experiments are still the most reliable data source on ship resistance determination. The bare hull form of underwater vehicle resistance is based on the model experiments and CFD results. The towing mechanism arrangement should be considered at model. Therefore, towing mechanism is designed for model testing. This paper discusses the towing method and result between model test and CFD. This paper also makes comparison of wave formation Towing tank test and CFD at various speeds. The model was tested with bare hull form of underwater vehicle in the Ship Model Towing Tank at Marine Hydrodynamics Centre, Myanmar Maritime University. CFD analysis is also carried out and the results are compared for surface condition. The three software packages XFLOW, XMESH and XPAN are used for CFD simulations. The comparison of results shows that the coefficient differences are less staggered based on the speed.

Joint High Speed Sealift (JHSS) Segmented Model Test Results

2012 ◽  
Author(s):  
Dominic Piro ◽  
Thomas C. Fu ◽  
Kevin J. Maki
Keyword(s):  
High Speed ◽  
Large Data ◽  
Torsional Stiffness ◽  
Data Set ◽  
Segmented Model ◽  
Test Matrix ◽  
Operational Conditions ◽  
Wide Range ◽  
Vibrational Characteristics ◽  
Water Test

The Joint High Speed Sealift segmented model (Model 5663) tests performed in 2007, in the Maneuvering and Seakeeping Basin at the Naval Surface Warfare Center, Carderock Division, were designed to provide a large data set for validation of numerical simulations. Model 5663 is a segmented structural ship model that has scaled longitudinal bending and torsional stiffness. The scaled stiffness is obtained by building a backspline into the model that accounts for the bending stiffness and cutting the shell in several places, segmenting it to isolate the stiffness to the backspline. The alternative way to obtain structural loads would be to build a model with scaled plates and stiffeners; however, this would be very difficult and expensive. The backspline allows the stiffness to be scaled properly while using reasonable materials and simple construction. The hull segments of the model are connected with silicone to maintain a watertight connection. The model is self propelled and steered during data collection. The test matrix spans a wide set of wave conditions, including regular and irregular seas, with heading angles spanning the possible range. A wide range of speeds are also included, with Froude numbers ranging from 0 to 0.43. This test matrix, which includes about 2000 runs, allows for validation of codes from still water test, through operational conditions, to extreme design load determination. Different aspects of the data have been studied, but much is still left to be considered. An aspect of the model tests that has not previously been considered in detail is the hydroelastic response of the vessel. Hydroelastic phenomena are a subset of fluid-structure interaction problems where the elasticity of the structure is important. The vibrational characteristics of the model are determined. The main phenomena of interest are springing and whipping, and an analysis of the springing response and the whipping response in head seas is also discussed.

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