Scale Effect Studies on Hydrodynamic Performance for DTMB 5415 Using CFD

2018 ◽  
Author(s):  
Heng Zhang ◽  
Hang Zhang ◽  
Xuanshu Chen ◽  
Hao Liu ◽  
Xianzhou Wang
Keyword(s):  
Degrees Of Freedom ◽  
Wave Pattern ◽  
Resistance Coefficient ◽  
Body Motion ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Ship Motions ◽  
Calm Water ◽  
Unsteady Rans ◽  
Scale Design

Making CFD with the capability of predicting ship scale design performance, rather than relying on scale model tests will help reduce design costs and provide a greater opportunity to develop more energy efficient ship designs. The key objective of this paper is to perform a fully nonlinear unsteady RANS simulation to predict the ship motions and resistance of a full scale DTMB 5415 ship model. The analyses are performed at design speeds, at a certain Fr number, using in-house computational fluid dynamics (CFD) to solve RANS equation coupled with six degrees of freedom (6DOF) solid body motion equations. RANS equations are solved by finite difference method and PISO arithmetic. Computations have been made using structured grid with overset technology. Simulation results shown that the total resistance coefficient in calm water at service speed is predicted by 2.36% error compared to the related towing tank results. The ship resistance for different scale demonstrated that the current in-house CFD model could predict the resistance in a reasonable range of the EFD data. The comparison of flow field for wave pattern for different scale model were analyzed and discussed.

Unsteady Viscous CFD Simulations of KCS Behaviour and Performance in Head Seas

2018 ◽  
Author(s):  
LiXiang Guo ◽  
JiaWei Yu ◽  
JiaJun Chen ◽  
KaiJun Jiang ◽  
DaKui Feng
Keyword(s):  
Degrees Of Freedom ◽  
Transfer Functions ◽  
Resistance Coefficient ◽  
Full Scale ◽  
Body Motion ◽  
Ship Motions ◽  
Added Resistance ◽  
Viscous Effects ◽  
Head Waves ◽  
And Performance

It is critical to be able to estimate a ship’s response to waves, since the added resistance and loss of speed may cause delays or course alterations, with consequent financial repercussions. Traditional methods for the study of ship motions are based on potential flow theory without viscous effects. Results of scaling model are used to predict full-scale of response to waves. Scale effect results in differences between the full-scale prediction and reality. The key objective of this study is to perform a fully nonlinear unsteady RANS simulation to predict the ship motions and added resistance of a full-scale KRISO Container Ship. The analyses are performed at design speeds in head waves, using in house computational fluid dynamics (CFD) to solve RANS equation coupled with two degrees of freedom (2DOF) solid body motion equations including heave and pitch. RANS equations are solved by finite difference method and PISO arithmetic. Computations have used structured grid with overset technology. Simulation results show that the total resistance coefficient in calm water at service speed is predicted by 4 .68% error compared to the related towing tank results. The ship motions demonstrated that the current in house CFD model predicts the heave and pitch transfer functions within a reasonable range of the EFD data, respectively.

Numerical Study on Scale Effect of KCS

2019 ◽  
Author(s):  
Yujie Zhou ◽  
Liwei Liu ◽  
Xiao Cai ◽  
Dakui Feng ◽  
Bin Guo
Keyword(s):  
Scale Effect ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Numerical Study ◽  
The Body ◽  
The Self ◽  
Body Motion ◽  
Propulsion Performance ◽  
Calm Water ◽  
Unsteady Rans

Abstract The key objective of this paper is to perform a fully nonlinear unsteady RANS simulation to predict the self-propulsion performance of KCS at two different scales. This simulations are performed at design speeds in calm water, using inhouse computational fluid dynamics (CFD) to solve RANS equation coupled with two degrees of freedom (2DOF) solid body motion equations including heave and pitch. The SST k-ω turbulence equation is discretized by finite difference method. The velocity pressure coupling is solved by PISO algorithm. Computations have used structured grid with overset technology. The single-phase level-set method is used to capture the free surface. The simulations of self-propulsion are based on the body-force method. The PID control method is applied to match the speed of KCS by changing the propeller rotation speed automatically. In this paper, the self-propulsion factors of KCS at two scales are predicted and the results from inhouse CFD code are compared with the EFD date, and then the reasons for the scale effect have been discussed.

Numerical Simulation of Damaged Ship’s Motion in Beam Waves

2019 ◽  
Author(s):  
Qing Wang ◽  
Xuanshu Chen ◽  
Liwei Liu ◽  
Xianzhou Wang ◽  
MingJing Liu
Keyword(s):  
Degrees Of Freedom ◽  
Body Motion ◽  
Ship Motions ◽  
Rans Equations ◽  
Six Degrees Of Freedom ◽  
Calm Water ◽  
Unsteady Simulation ◽  
Ship Hydrodynamic ◽  
Physical Phenomena ◽  
Damaged Ship

Abstract The dangerous situation caused by the breakage of the ship will pose a serious threat to crew and ship safety. If the ship’s liquid cargo or fuel leaks, it will cause serious damage to the marine environment. If damage occurs accompanied by roll and other motions, it may cause more dangerous consequences. It is an important issue to study the damaged ship in time-domain. In this paper, the motions of the damaged DTMB 5512 in calm water and regular beam waves are studied numerically. The ship motions are analyzed through CFD methods, which are acknowledged as a reliable approach to simulate and analyze these complex physical phenomena. An in-house CFD (computational fluid dynamics) code HUST-Ship (Hydrodynamic Unsteady Simulation Technology for Ship) is used for solving RANS equations coupled with six degrees of freedom (6DOF) solid body motion equations. RANS equations discretized by finite difference method and solved by PISO algorithm. Level set was used for free surface simulation. The dynamic behavior of model was observed in both intact and damaged condition. The heave, roll and pitch amplitudes of the damaged ship were studied in calm water and beam wave of three wavelengths.

Numerical Simulation of Hydrodynamic Performance of Multi-Hull Catamaran With 3DOF Motion

2018 ◽  
Author(s):  
Rijie Li ◽  
Liwei Liu ◽  
Lixiang Guo ◽  
Dakui Feng ◽  
Xianzhou Wang
Keyword(s):  
Fluid Dynamics ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Turbulence Models ◽  
Body Motion ◽  
Hydrodynamic Performance ◽  
Experimental Fluid Dynamics ◽  
Calm Water ◽  
Sinkage And Trim ◽  
Resistance Prediction

This paper presents CFD to study the hydrodynamic performance for the high-speed, multi-hull Catamaran advancing in calm water. It uses inhouse computational fluid dynamics (CFD) code to solve RANS equation coupled with six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO arithmetic. Computations have been made using structured grid with overset technology. Turbulence models used the anisotropic two equations Shear Stress Transport (SST) k-ω model. Single phase level set was used for free surface simulation. A good agreement on the resistance prediction between CFD and experimental fluid dynamics (EFD) has been observed (on the resistance prediction of about 4.0%). Differences between CFD and EFD have been seen for the 3 degrees of freedom (3DOF) motion, whereas larger discrepancy is observed for the sinkage and trim estimation (about 8.0%).

The Flooding After Damage of a Warship with Complex Internal Compartments - Experiments on a Fully Constrained Model in Calm Water and Regular Beam Seas

2012 ◽  
Vol 154 (A2) ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Code ◽  
Scale Model ◽  
Experimental Program ◽  
Hull Form ◽  
Video Footage ◽  
Unconstrained Model ◽  
Beam Seas ◽  
Calm Water ◽  
Constrained Model

In order to provide data to assist in developing and validating a numerical code to simulate the flooding immediately following damage scale model experiments were conducted on a fully constrained model to investigate the progressive flooding through a complex series of internal compartments within a generic destroyer type hull form. A 3.268 metre long model of a generic destroyer hull form with a simplified, typical internal arrangement was constructed to cover the configuration of greatest interest. A very rapid damage opening scenario was simulated by rupturing a taut membrane covering an opening. The model was instrumented to measure the levels of water and the air pressures in various compartments. In addition, video footage was obtained of the flooding process from both internally and externally of the model. Previous work presented by Macfarlane et al. (2010) showed the results for the unconstrained model. This paper reports on the outcomes from the experimental program where the model was fully constrained in all six degrees of freedom. Firstly, tests were conducted in calm water with damage opening extents ranging from 50% to 100%. When the damage opening was only 50% the rate of rise of water in each of the compartments was only marginally slower than for the 100% damage extent case. Secondly, the test results in calm water were compared against results from tests in regular beam seas. A ‘set-up’ of water inside each of the compartments on the 2nd Deck was found during the wave tests. The result of this is that the mean equilibrium water level in each compartment in the regular beam sea cases is noticeably higher than the equivalent calm water case, particularly for the two compartments on the port side, away from the damage. Finally, analysis of the data from further calm water and beam sea tests suggests that a similar result also occurs when the model is fixed at various non-zero heel angles.

An Experimental Investigation of Roll Motions of an FPSO

2008 ◽  
Author(s):  
Paulo T. T. Esperanc¸a ◽  
Joel S. Sales ◽  
Stergios Liapis ◽  
Joa˜o Paulo J. Matsuura ◽  
Wes Schott
Keyword(s):  
Degrees Of Freedom ◽  
Wind Waves ◽  
Scale Model ◽  
Ship Motions ◽  
Random Waves ◽  
Six Degrees Of Freedom ◽  
Campos Basin ◽  
Waves And Currents ◽  
Offshore Development ◽  
Bilge Keel

FPSO roll motions can be major contributor to riser fatigue. This is especially true in regions where wind, waves and currents are non-collinear. Roll motions as high as 23 degrees have been reported in the Campos Basin. The most common roll mitigation strategy consists of adding bilge keels to the FPSO. Motivation for this work came from a need to develop a better understanding of roll motions as a function of bilge keel width. In addition to roll motions, the hydrodynamic forces on the bilge keels were measured. A series of tests were conducted at the LabOceano offshore basin. This new facility has a length of 4 0 m, a width of 30 m, a depth of 15 m and is equipped with a multi-flap wave generator on one side. A ship-shaped FPSO design with sponsons for a deepwater offshore development in Brazil was tested. It has a length of 316 m, a breadth of 57.2 m and a draft of 28.3 m. A 1:70 scale model was constructed. A horizontal soft mooring system consisting of four lines with springs was used. Regular waves of different amplitudes as well as random waves were generated in the basin. Two different loading conditions, ballast (draft = 6.7 m) and loaded (draft = 21.7 m), as well as three wave headings, beam seas (90°), and quartering seas (22.5°, 45°) were considered. Tests were undertaken for four bilge keel configurations, corresponding to a case without bilge keels, as well as bilge keels of 3 different widths (1 m, 2 m and 3 m). In all cases, the bilge keels had a length of 200 m. An optical system was used to measure ship motions in all six degrees of freedom. The hydrodynamic loads on the bilge keels were measured using strain gages.

Numerical Simulation of Ship-Ship Interactions in Waves

2019 ◽  
Author(s):  
Xueshen Xie ◽  
Yuxiang Wan ◽  
Qing Wang ◽  
Hao Liu ◽  
Dakui Feng
Keyword(s):  
Numerical Simulation ◽  
Degrees Of Freedom ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Body Motion ◽  
Structured Grid ◽  
Six Degrees Of Freedom ◽  
Unsteady Rans ◽  
Small Ship ◽  
The Impact

Abstract A numerical simulation of the hydrodynamic interaction and attitude of a ship and two ships of different sizes navigating in parallel in waves were carried out in this paper. The study of the two ships navigating in parallel is of great significance in marine replenishment. This paper used in house computational fluid dynamics (CFD) code to solve unsteady RANS equation coupled with six degrees of freedom (6DOF) solid body motion equations. URANS equations are solved by finite difference method and PISO algorithm. Structured grid with overset technology have been used to make computations. Turbulence models used the Shear Stress Transport (SST) k-ω model. The method used for free surface simulation is single phase level set. In this paper, two DTMB 5415 with different scales are selected for simulation analysis. This paper analyzed the impact of the big ship on the small ship when the two ships were navigating in parallel. This paper also analyzed the relationship between interaction and velocity between hulls, which has certain guiding significance for the ship’s encounter on the sea.

RANS Simulation of the Flow Around a Ship Advancing in Shallow Water

2020 ◽  
Author(s):  
Yan-Yun Zhang ◽  
Zao-Jian Zou ◽  
Jian-Xi Yao
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Grid Method ◽  
Wave Pattern ◽  
Resistance Coefficient ◽  
Water Condition ◽  
Calm Water ◽  
Wigley Hull ◽  
Overset Grid Method ◽  
Sinkage And Trim

Abstract This paper simulates the viscous flow about a ship advancing in calm water of different water depths using Reynolds-Averaged Naiver-Stokes (RANS) method. A Wigley hull is taken as the study object, and the hull is free in sinkage and trim in the simulations. The fluid domain is discretized into hexahedral structured grids. The overset grid method and the deforming grid method are applied in different cases to capture the ship’s sinkage and trim motion. The grid independence analysis and validation of numerical method are carried out under deep water condition. Then, systematic simulations are carried out under shallow water condition at different ship speeds. The resistance performance and the wave pattern characteristics are compared with deep water condition to demonstrate the shallow water effect. Furthermore, resistance coefficient results under water depth-to-draft ratios of 2.0 and 1.5 are presented and compared. All simulations show great consistency with the theoretical and other potential theory based numerical results.

Prediction of Resistance and Self-Propulsion Characteristics of a Full-Scale Naval Ship by CFD-Based GEOSIM Method

2020 ◽  
pp. 1-16 ◽  
Author(s):  
Cihad Delen ◽  
Ugur Can ◽  
Sakir Bal
Keyword(s):  
Degrees Of Freedom ◽  
Full Scale ◽  
The Self ◽  
Body Motion ◽  
Ship Motions ◽  
Naval Research ◽  
Propulsion Performance ◽  
Office Of Naval Research ◽  
Naval Ship ◽  
Computational Fluid Dynamics Cfd

Resistance and self-propulsion characteristics of a naval ship at full scale have been investigated by using Telfer’s GEOmetrically SIMilar (GEOSIM) method based on the computational fluid dynamics (CFD) approach. For this purpose, first, the resistance forces of the Office of Naval Research Tumblehome (ONRT) hull have been computed at different three model scales by using the overset mesh technique. The full-scale resistance and nominal wake fraction of the ONRT hull have been estimated by using Telfer’s GEOSIM method. Resistance and nominal wake fraction have then been compared with those of CFD at full scale. Later, the self-propulsion characteristics of the ONRT hull have been examined using Telfer’s GEOSIM method based on the CFD approach. Self-propulsion factors at the full-scale hull have been predicted by using the SST k-ω turbulence model to involve 2-degrees of freedom ship motions (heave and pitch). Rotational motion of the propeller has also been simulated by using the rigid body motion technique. The results calculated by Telfer’s GEOSIM method and the 1978 International Towing Tank Conference (ITTC) extrapolation technique have been compared with each other and discussed with those of the CFD approach at full scale. It was found that the full-scale results (both resistance and self-propulsion factors) predicted by Telfer’s GEOSIM method are closer to those of the CFD approach than those of the 1978 ITTC technique. It can be noted that Telfer’s GEOSIM method is fast, robust, and reliable and can be used as an alternative to the 1978 ITTC method for predicting the self-propulsion performance of a full-scale ship.

scholarly journals Prediction of Ship Unsteady Maneuvering in Calm Water by a Fully Nonlinear Ship Motion Model

2012 ◽  
Vol 2012 ◽  
pp. 1-11
Author(s):  
Ray-Qing Lin ◽  
Tim Smith ◽  
Michael Hughes
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Ship Motion ◽  
Ship Motions ◽  
Motion Model ◽  
Forward Speed ◽  
Fully Nonlinear ◽  
Six Degrees Of Freedom ◽  
Calm Water

This is the continuation of our research on development of a fully nonlinear, dynamically consistent, numerical ship motion model (DiSSEL). In this study we will report our results in predicting ship motions in unsteady maneuvering in calm water. During the unsteady maneuvering, both the rudder angle, and ship forward speed vary with time. Therefore, not only surge, sway, and yaw motions occur, but roll, pitch and heave motions will also occur even in calm water as heel, trim, and sinkage, respectively. When the rudder angles and ship forward speed vary rapidly with time, the six degrees-of-freedom ship motions and their interactions become strong. To accurately predict the six degrees-of-freedom ship motions in unsteady maneuvering, a universal method for arbitrary ship hull requires physics-based fully-nonlinear models for ship motion and for rudder forces and moments. The numerical simulations will be benchmarked by experimental data of the Pre-Contract DDG51 design and an Experimental Hull Form. The benchmarking shows a good agreement between numerical simulations by the enhancement DiSSEL and experimental data. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder, which is included using a flow acceleration factor.

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