Figure 1 - uploaded by Metin Taylan
Content may be subject to copyright.
Source publication
This paper analyzes the effect of damping on nonlinear roll motion of ships advancing in beam seas. As it is known, roll damping is a very important parameter in estimating ship responses in calm water and waves. Therefore, it has been studied by many researchers in different ways. However, it seems that it has been far from being complete and much...
Similar publications
In this work, a hybrid machine learning method, which uses ML strategies to model high-order force components within a low-order equation of motion, is considered in the context of the global wave-induced loads of a ship in irregular waves. It is shown that the method can make predictions in a range of wave conditions even when the training data se...
Dynamic vertical bending moments are determined for a military vessel hull in still water and under head waves, with a weakly nonlinear method. The domain for hydrostatic and undisturbed pressures integration is time-variant and generated with a quad-tree adaptive mesh algorithm, on which exact formulations for pressure on polygonal elements are us...
Nonlinear rolling of typical inland container vessels subjected to severe beam wind was investigated in series of numerical tests. The mean wind speed was estimated from the stability rules, and the wind gusts from the appropriate wind spectrums. From the time history of vessel motion, the probability that the open container hold would be flooded,...
According to the Second Generation Intact Stability Criteria (SGISC), developed by IMO, assessment of dynamic intact stability of ships can be done using either of three " levels " of assessment: Levels 1 and 2 involve significant simplifications, whereas Level 3 is based on advanced numerical simulation methods and allows, in principle, using prob...
Citations
... Bilge keels damping can reach 60%-70% of viscous damping. Radiation damping can be predicted accurately by calculation, but eddy making damping and bilge keels damping must be predicted by experiment in the towing tank [7]. Generally bilge keels is installed in the mid ship until 1/3 length of the ship. ...
Stability of a ship is very influenced by ship’s roll motion, which is able to cause the ship to capsize. One of the main component which influence the roll motion, is the usage of motion damper at the ship’s hull. Bilge keel is a kind of passive damper whose construction is easy and does not require special system in the operation. The suitable bilge keel size is able to reduce excessive ship motion response when experiencing excitation force. This paper investigates the influence of bilge keel to the motion response of the ship by using a fishing vessel model with round bilge. The study was carried out by model experiment in the calm water and oblique wave using 6 types of bilge keel variation in its length and width. The results showed that the application of bilge keel is able to reduce about 37% motion response of the vessel; and the increase area of bilge keel also reduce the roll damping to 59%. It also can be concluded that common design bilge keel for merchant ship can be applied to the fishing vessel.
... In order to do that, some assumptions have been made on incident waves and geometry of the converter, as well as on their mutual interaction, with the aim to make them interact in a proper way that is representative of real interactions. Some of these impositions were assumed on the basis of manuals of naval architecture [17][18][19], papers and works of thesis about ship stabilization, control and optimisation [14][15][16][17]; others have been added to give physical sense to the entire model. All the adopted assumptions and conventions are described in Appendix D. ...
This paper presents a theoretical and experimental investigation about the modelling of a 1:45 scale prototype Wave Energy Converter (WEC). An analytical model is implemented to describe its behaviour in a wave tank. The aim is to provide a contribution to modelling tools used for WEC characterization and design. Hydrodynamic characterization software is avoided in favour of a simpler and more versatile design tool destined to a wider range of users. Therefore, an alternative approach is presented, based on mechanical analogies and the use of Matlab/Simulink/SimMechanics environment. This analytical model was constructed using linear wave theory, coupled with a non-linear model for the device and its power take-off system (PTO). Assumptions on incident waves and geometric properties of the device were required and implemented on the basis of literature of naval architecture, ships stabilization and control issues. Simulation results were compared and validated with those obtained in the same range of experimental tests of the prototype in wave tank. Trends and values of both investigation techniques show a good agreement, indicating the validity of the methodology adopted and leaving space for future improvements of the same. Finally, as example of application, the model was applied in a show case in order to estimate the energy yield by the WEC if scaled to real size, using Froude scaling. Results are encouraging and show the viability of the proposed design.
... This is due to fact that roll damping has a large influence on the roll motion up to the point that it may even cause the vessel's capsize (Haddara, 1989). It plays a dominant role on reducing the roll amplitude and that is why many researchers pay attention to the improvement of its prediction (Pesman at al, 2007). Since 1970s, many investigations have been carried out on the effects of bilge keels, which are used for many years on ships to enhance roll damping (Ikeda, 1977, Ikeda, 1978, Ikeda, 2004. ...
A study of the roll damping of a two-dimensional FPSO model produced by bilge keels using CFD method is presented in this paper. The tool to be utilized is the well-known code Star-CCM+, which uses the Volume of Fluid (VOF) approach to capture the free surface. The results are validated by comparison with experiments. Using the results from a number of simulations, the roll damping coefficient resulting from locating the bilge keels at different positions will be calculated. The analysis of the rolling damping coefficients for the different locations will provide a useful design tool for optimising the roll damping of vessels with bilge keels.
... Dierent numerical methods and models are developed and tested for specic application to the non-linear rolling of ship hull sections. A non-linear rolling hull with forward velocity was numerically investigated by Pesman et al. (2007). A mid-size twin-screw shing vessel was considered. ...
... Even though a single hull was employed, no appendages were considered. Pesman et al. (2007) found that increasing the metacentric height of a hull (GM) did not reduce peak resonant amplitudes, but shifted the resonant frequency. Bilge-keels were found to damp motion by about 35 % at the ship's resonant frequency. ...
CONTENTS - BOJANOWSKA MILENA Handling and transportation properties of rapeseed biomass as affected by particle size ... 5 DYDKOWSKI GRZEGORZ, URBANEK ANNA The impact of an integrated fare system on the public transport demand: A literature review ... 16 GNACIŃSKI PIOTR, MUC ADAM, PEPLIŃSKI MARCIN Line start permanent magnet synchronous motor supplied with voltage containing subharmonics ... 28 GARCZYŃSKA ILONA Research and applications of artificial neural networks in spatial analysis: Review ...35 BUKOWSKA-PIETRZYŃSKA AGNIESZKA, MOTOWIDLAK URSZULA Supply chain adaptability as a response to disruptions – theoretical and empirical aspects ... 46 KACPRZAK PAWEŁ Assessment of cargo handling operation efficiency in the Clarion-Clipperton Zone for standard bulk carriers inthe view of significant amplitudes of roll as a limiting criterion ... 55 MAGRYTA-MUT BEATA Modeling safety of port and maritime transportation systems ... 65 WIKTOROWSKA-JASIK ANNA Carsharing as an example of smart mobility – comparative study Poland–Germany ... 75 HERDZIK JERZY Marine fuel from the past to the future ...83
In recent decades, study of the behavior of ship motion in waves has been considered by researchers. In this paper, mathematical modeling of nonlinear coupling of roll and heave modes of a ship under harmonic excitation in heave direction is studied. The method of multiple scales is used to solve nonlinear equations. Equations of motion in harmonic excitation are studied. In order to validate the responses obtained by the method of multiple scales, the response obtained for a sample is compared with the numerical solution of the equation and good agreement is obtained. Analysis of ship motion requires time consuming computations in large scaled model. In addition to evaluation of nonlinear coupling roll motion with heave in forced vibrations, the motion is modeled with a simple mechanical system that includes mass–spring-damper and pendulum under identical conditions and the response of equal system with response of the original system being consistent. Sensitivity analysis was carried out for nonlinear coupling of roll and heave in harmonic excitation with local and partial derivative methods and the results from the two methods are compared.
This paper presents a theoretical and experimental investigation about the modelling of a 1:45 scale prototype Wave Energy Converter (WEC). An analytical model is implemented to describe its behaviour in a wave tank. The aim is to provide a contribution to modelling tools used for WEC characterization and design. Hydrodynamic characterization software is avoided in favour of a simpler and more versatile design tool destined to a wider range of users. Therefore, an alternative approach is presented, based on mechanical analogies and the use of Matlab/Simulink/SimMechanics environment. This analytical model was constructed using linear wave theory, coupled with a non-linear model for the device and its power take-off system (PTO). Assumptions on incident waves and geometric properties of the device were required and implemented on the basis of literature of naval architecture, ships stabilization and control issues. Simulation results were compared and validated with those obtained in the same range of experimental tests of the prototype in wave tank. Trends and values of both investigation techniques show a good agreement, indicating the validity of the methodology adopted and leaving space for future improvements of the same. Finally, as example of application, the model was applied in a show case in order to estimate the energy yield by the WEC if scaled to real size, using Froude scaling. Results are encouraging and show the viability of the proposed design.
Assessment of ship survivability is a main requirement that must be satisfied before the ship isoperated. Some assessments of ship survivability which has been applied by IMO such as Intact Stability and Damage Stability in calm water needs to be developed. Sometimes ships are operated in rough water with irregular waves, so the future criteria of ship stability should be associated with ship motion and capsizinginthewaves. Ship capsizing isalways correlated with non-linier ship motion. This paper discusses how to modify intact stability criteria to be righting lever arm onthecalm waterwhich can be used to assess ship survivability from capsizing in the waves using safe basin erosion method. The results shows that the modified IMO‘s Intact Stability Criteria can be considered as assesment of survival of ship capsizing. And the bilge keels have significat effect for improving the survivability of ship capsizing.
Active fin control is the most effective anti-rolling approach to ship stabilization. However, an accurate model of the whole nonlinear dynamic ship system under random wave or wind impact is difficult to obtain. This study develops an intelligent guarded heuristic genetic algorithm fin controller, including a heuristic genetic algorithm fin controller and a guarded fin controller, to identify the optimum solution for ship stabilization system. In the heuristic genetic algorithm fin controller design, the gradient-descent training is embedded into a traditional genetic algorithm to construct the main controller, which consequently determines the optimum fin control angle in response to uncertainties. To ensure that the system states are around a defined bound region, the proposed system uses a guarded fin controller to adjust the control angle. The stabilization system uses a gyroscope and accelerometer to detect rolling conditions, and the gathered data are fed to an embedded microcontroller to calculate output commands. To verify the performance of the proposed guarded heuristic genetic algorithm fin controller, an analogous two-wheeled robot balance model and experimental platform are adopted in the simulations and experiments as the preliminary tool. Simulations and experimental results confirm the effectiveness of the proposed system, and this study compares its performance with other fin control schemes.
