Numerical and experimental study on seakeeping performance of a SWATH vehicle in head waves

2017 ◽  
Vol 68 ◽  
pp. 262-275 ◽  
Author(s):  
X.S. Sun ◽  
C.B. Yao ◽  
Y. Xiong ◽  
Q. Ye
Keyword(s):  
Experimental Study ◽  
Seakeeping Performance ◽  
Head Waves

Experimental Study on Seakeeping Performance of a Catamaran with Asymmetric Demi-Hulls

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
S. Ikezoe ◽  
N. Hirata ◽  
H. Yasukawa
Keyword(s):  
Experimental Study ◽  
Ship Motion ◽  
Added Resistance ◽  
Scaled Model ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Lateral Space ◽  
Design Speed ◽  
Resistance Performance ◽  
Regular Head Waves

To capture the seakeeping performance of a catamaran with asymmetric demi-hulls, tank tests were carried out in regular head waves using a scaled model with 2.036 m in length. The lateral space between the demi-hulls was changed in the tests as W/B=2.55, 2.90 and 3.25, where W denotes breadth overall and B the breadth of the demi-hull. Also, two models with different water lines of inside flat and outside round (IF-type) and of outside flat and inside round (OF-type) were used. OF-type is superior to IF-type in both ship motion and added resistance performances in waves at the design speed. In IF-type series, the smallest clearance, W/B=2.55 is the best in the added resistance performance.

scholarly journals Experimental study of hydrodynamic forces acting on ship bow during wave capture

2019 ◽  
pp. 146-152
Author(s):  
Pavel Burakovskiy
Keyword(s):  
Experimental Study ◽  
Test Data ◽  
Model Test ◽  
Hydrodynamic Forces ◽  
Hydrodynamic Loads ◽  
Test Tank ◽  
Head Waves ◽  
Negative Effect

This paper studies behavior of ship in head waves, when her bow dips under water, which leads to hydrodynamic forces and moments to be assessed. This paper presents model test data obtained in the test tank on the model of ship bow (hydrodynamic loads on forecastle deck during wave capture) as well as updates the coefficient of flow around the bow. The study also shows that bulwark has negative effect upon safety in these conditions because it significantly increases hydrodynamic loads on the deck.

Evaluation of a Small and Fast Planing Boat’s Seakeeping Performance at the Design Stage

2015 ◽  
Author(s):  
Dong Jin Kim ◽  
Sun Young Kim
Keyword(s):  
Model Tests ◽  
Full Scale ◽  
Scale Model ◽  
Design Stage ◽  
Small Scale ◽  
Irregular Wave ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Scale Ratio ◽  
Free Running

Seakeeping performance of a planing boat should be sufficiently considered and evaluated at the design stage for its safe running in rough seas. Model tests in seakeeping model basins are often performed to predict the performance of full-scale planing boats. But, there are many limitations of tank size and wave maker capacity, in particular, for fast small planing boats due to small scale ratio and high Froude numbers of their scale models. In this research, scale model tests are tried in various test conditions, and results are summarized and analyzed to predict a 3 ton-class fast small planing boats designed. In a long and narrow tank, towing tests for a bare hull model are performed with regular head waves and long crested irregular head waves. Motion RAOs are derived from irregular wave tests, and they are in good agreements with RAOs in regular waves. Next, model ships with one water-jet propulsion system are built, and free running model tests are performed in ocean basins. Wave conditions such as significant heights, modal periods, and directions are varied for the free running tests. Motion RMS values, and RAOs are obtained through statistical approaches. They are compared with the results in captive tests for the bare hull model, and are used to predict the full-scale boat performances.

The Experimental Study of Ultrasonic Testing Prestressed Bellows Pore Grouting Quality

2014 ◽  
Vol 711 ◽  
pp. 461-468 ◽  
Author(s):  
Shao Lin Zhou ◽  
Feng Zhang ◽  
Yuan Cao
Keyword(s):  
Experimental Study ◽  
Ultrasonic Testing ◽  
Concrete Slab ◽  
Ultrasonic Method ◽  
Test Results ◽  
Concrete Panels ◽  
Head Waves ◽  
Different Thickness ◽  
Regular Patterns

The ultrasonic method can be used for testing and analyzing the pore size of concrete. By studying the spectrum curves which is formed by ultrasonic transmitting at different thickness concrete panels can we get different time regular patterns of head waves formed by ultrasonic going through homogeneous concrete, compact grouting pore, grouting incompact pore, not grouting pore. All these provide a basis for predicting prestressed bellows pore grouting quality and judging whether there is interspace in pore. By artificially setting defects in bellows pore, for example, filling the pore to completely empty, 1/4 compact, 1/2 compact, 3/4 compact, fully compact and then embedding them in a concrete slab for ultrasonic testing. Test results show that the ultrasonic method can effectively evaluate the grouting quality of prestressed bellows pore.

scholarly journals Motion Prediction of Catamaran with a Semisubmersible Bow in Wave

2016 ◽  
Vol 23 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Hanbing Sun ◽  
Fengmei Jing ◽  
Yi Jiang ◽  
Jin Zou ◽  
Jiayuan Zhuang ◽  
...  
Keyword(s):  
Grid Method ◽  
Scale Model ◽  
Small Scale ◽  
Motion Prediction ◽  
Vertical Acceleration ◽  
Overset Grid ◽  
Motion Response ◽  
Movement Data ◽  
Seakeeping Performance ◽  
Head Waves

Abstract Compared with standard vessels, a slender catamaran with a semi-submerged bow (SSB) demonstrates superior seakeeping performance. To predict the motion of an SSB catamaran, computational fluid dynamics methods are adopted in this study and results are validated through small-scale model tests. The pitch, heave, and vertical acceleration are calculated at various wavelengths and speeds. Based on the overset grid and motion region methods, this study obtains the motion responses of an SSB catamaran in regular head waves. The results of the numerical studies are validated with the experimental data and show that the overset grid method is more accurate in predicting the motion of an SSB catamaran; the errors can be controlled within 20%. The movement data in regular waves shows that at a constant speed, the motion response initially increases and then decreases with increasing wavelength. This motion response peak is due to the encountering frequency being close to the natural frequency. Under identical sea conditions, the motion response increases with the increasing Froude number. The motion prediction results, that derive from a short-term irregular sea state, show that there is an optimal speed range that can effectively reduce the amplitude of motion.

scholarly journals Full-Scale CFD Analysis of Double-M Craft Seakeeping Performance in Regular Head Waves

2021 ◽  
Vol 9 (5) ◽  
pp. 504
Author(s):  
Deniz Ozturk ◽  
Cihad Delen ◽  
Simone Mancini ◽  
Mehmet Ozan Serifoglu ◽  
Turgay Hizarci
Keyword(s):  
Full Scale ◽  
Stokes Wave ◽  
Added Resistance ◽  
Motion Responses ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Calm Water ◽  
Maximum Improvement ◽  
Fifth Order ◽  
Regular Head Waves

This study presents the full-scale resistance and seakeeping performance of an awarded Double-M craft designed as a 15 m next-generation Emergency Response and Rescue Vessel (ERRV). For this purpose, the Double-M craft is designed by comprising the benchmark Delft 372 catamaran with an additional center and two side hulls. First, the resistance and seakeeping analyses of Delft 372 catamaran are simulated on the model scale to verify and compare the numerical setup for Fr = 0.7. Second, the seakeeping performance of the full-scale Double-M craft is examined at Fr = 0.7 in regular head waves (λ/L = 1 to 2.5) for added resistance and 2-DOF motion responses. The turbulent flow is simulated by the unsteady RANS method with the Realizable Two-Layer k-ε scheme. The calm water is represented by the flat VOF (Volume of Fluid) wave, while the incident long waves are represented by the fifth-order Stokes wave. The residual resistance of the Double-M craft is improved by 2.45% compared to that of the Delft 372 catamaran. In the case of maximum improvement (at λ/L = 1.50), the relative added resistance of the Double-M craft is 10.34% lower than the Delft 372 catamaran; moreover, the heave and pitch motion responses were 72.5% and 35.5% less, respectively.

Experimental study on hydrodynamic performance of SWATH vessels in calm water and in head waves

2019 ◽  
Vol 85 ◽  
pp. 88-106 ◽  
Author(s):  
E. Begovic ◽  
C. Bertorello ◽  
A. Bove ◽  
F. De Luca
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Head Waves ◽  
Calm Water

scholarly journals On the Comparative Seakeeping Analysis of the Full Scale KCS by Several Hydrodynamic Approaches

2020 ◽  
Vol 8 (12) ◽  
pp. 962
Author(s):  
Florin Pacuraru ◽  
Leonard Domnisoru ◽  
Sandita Pacuraru
Keyword(s):  
Global Economy ◽  
Domain Boundary ◽  
Ship Motions ◽  
Ocean Engineering ◽  
Regular Waves ◽  
Transport Channel ◽  
Navier Stokes Equation ◽  
Seakeeping Performance ◽  
Strip Theory ◽  
Head Waves

The main transport channel of the global economy is represented by shipping. Engineers and hull designers are more preoccupied in ensuring fleet safety, the proper operation of the ships, and, more recently, compliance with International Maritime Organization (IMO) regulatory incentives. Considerable efforts have been devoted to in-depth understanding of the hydrodynamics mechanism and prediction of ship behavior in waves. Prediction of seakeeping performances with a certain degree of accuracy is a demanding task for naval architects and researchers. In this paper, a fully numerical approach of the seakeeping performance of a KRISO (Korea Research Institute of Ships and Ocean Engineering, Daejeon, South Korea) container ship (KCS) container vessel is presented. Several hydrodynamic methods have been employed in order to obtain accurate results of ship hydrodynamic response in regular waves. First, an in-house code DYN (Dynamic Ship Analysis, “Dunarea de Jos” University of Galati, Romania), based on linear strip theory (ST) was used. Then, a 3D fully nonlinear time-domain Boundary Element Method (BEM) was implemented, using the commercial code SHIPFLOW (FLOWTECH International AB, Gothenburg, Sweden). Finally, the commercial software NUMECA (NUMECA International, Brussels, Belgium) was used in order to solve the incompressible unsteady Reynolds-averaged Navier–Stokes equation (RANSE) flow at ship motions in head waves. The results obtained using these methods are represented and discussed, in order to establish a methodology for estimating the ship response in regular waves with accurate results and the sensitivity of hydrodynamical models.

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