System-based prediction of maneuvering performance of twin-propeller and twin-rudder ship using a modular mathematical model (original) (raw)
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Scientia Iranica, 2017
In the recent years, di erent mathematical models have been suggested for maneuvering of displacement vessels, which are capable to estimate maneuvering of the vessel with acceptable precision. But, simulation of planing craft maneuverability through a mathematical model has not been developed yet. In this paper, a mathematical model is developed for maneuvering of the planing craft by including the rudder forces and moments. Di erent maneuvers, such as straight-line stability, course keeping, and turning circle, are executed through the mathematical model. Simulation results are validated with the published experimental results and it is shown that they are in good agreement. Finally, the in uence of rudder angle on maneuverability of planing craft is studied and, also, the e ect of aspect ratio has been investigated. The mathematical model and hydrodynamic coe cients presented in this paper can be applied for the optimization of planing craft maneuvering and the course control purposes.
Investigation of Twin-Screw Naval Ships Maneuverability Behavior
Journal of Ship Research, 2011
The problem of ship maneuverability has currently reached a significant consideration, both for merchant ships, with the adoption of IMO standards, and naval ships, with the production of various documents by NATO Specialist Teams. In literature, many works regarding maneuverability of single-screw slow/medium speed ships are present, while a lack of information about twin-screw ships (cruise ships, Ro/Ro ferries, megayachts, naval vessels) exists. These ships are usually characterized by different hull forms and more complex stern configuration because of the presence of appendages such as skegs, shaft lines, and brackets, which can strongly affect maneuverability behavior. In this work various prediction methods, namely statistical regressions, system identification, and RANSE, are investigated to evaluate twinscrew naval vessels maneuverability behavior. From this analysis, stern appendages influence (including also nonlinear effects resulting from hull/appendage interactions) resulted one of the peculiar characteristics of this type of ship, clearly affecting their maneuvering capabilities.
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Applied Ocean Research, 2019
Maneuverability is an important aspect of marine vehicle design. The performance of a rudder, as the most important means of maneuvering, has significant impacts on ship controllability characteristics. This study investigated the effect of five rudder profiles (NACA 0012, NACA0025, IFS, Fish tail, HSVA) on the turning characteristics of KCS containership model. This investigation was performed by direct simulation of the ship turning circle maneuver in computational fluid dynamic environment based on the ITTC verification procedure. All rudders were defined with the same lateral area. Simulations were conducted with the commercial software STAR-CCM+. The rudder turning and the ship's dynamic motion were modeled by the use of an overset technique and six-DOF dynamic solver, respectively. Roll, pitch and heave motions and forward speed reduction during the turning maneuver with different rudders were computed and compared. Results show that the rudder profiles designed specifically for marine applications (Fishtail, IFS and HSVA) perform better than the traditional NACA series.
Ship Maneuverability Experiments on Open Water with Rudder Model Variations: Case Study of SPB-XXOO
IPTEK The Journal for Technology and Science
Ship maneuverability is important to study because it affects safety. Moreover, if the ship operates in a narrow shipping lane, as experienced by SPUB that operated in Musi River. This research focuses on the experimental process of SPUB maneuvers in open water, especially for the turning circles' movement. The experiment was conducted using a prototype, model SPB-XXOO, which was equipped with components of the instrumentation system such as data logger and propulsion system. Both are integrated into the remote control and computer to perform control functions, calculations, data logging, and data transfer through the wireless communication system. The main controller of the propulsion system is an implanted program to deflect the rudder automatically. Three rudder models with variations in aspect ratios of 1.10, 1.65, and 2.20, also two variations of the rudder angle; 30o and 35o are used to test the model. GPS does the data acquisition process for each experimental process. Based on the analysis of the rudder model's effect, it was found that a rudder with a large aspect ratio provides better performance than a lower aspect ratio. The average increase in the maneuver performance of the rudder with the smallest to the most significant aspect ratio is 17.345%.
Evaluation of Mathematical Models for Tankers' Maneuvering Motions
Journal of ETA Maritime Science, 2017
In this study, the maneuvering performance of two tanker ships, KVLCC1 and KVLCC2 which have different stern forms are predicted using a system-based method. Two different 3 DOF (degrees of freedom) mathematical models based on the MMG(Maneuvering Modeling Group) concept areappliedwith the difference in representing lateral force and yawing moment by second and third order polynomials respectively. Hydrodynamic coefficients and related parameters used in the mathematical models of the same scale models of KVLCC1 and KVLCC2 ships are estimated by using experimental data of NMRI (National Maritime Research Institute). The simulations of turning circle with rudder angle ±35 o , zigzag(±10 o /±10 o) and zigzag (±20 o /±20 o) maneuvers are carried out and compared with free running model test data of MARIN (Maritime Research Institute Netherlands) in this study. As a result of the analysis, it can be summarised that MMG model based on the third order polynomial is superior to the one based on the second order polynomial in view of estimation accuracy of lateral hull force and yawing moment.
Evaluation of Planing Craft Maneuverability Using Mathematical Modelling
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Ship transportation is increasing globally as is the risk of collision especially in congested areas. Numerical modeling method is a major simulation method to predict ship maneuverability. Ship maneuvering in calm water is an important topic to avoid collisions and leads to safe navigation. Therefore, reliable ship maneuvering simulations are required for incident analysis and prevention. In recent time within the research community orientated towards ship hydrodynamics an increasing attention has been paid to simultaneous solution of the planing ship maneuvering problem. The maneuverability of planing craft has been the subject of many research projects during the last few decades. To assess the maneuverability of planing craft at an early design stage, reliable simulation models are required. Traditionally, these tools have used empiric descriptions of the forces and moments on the planing craft’s hull. Ship maneuvering calculations, horizontal plane motion control and developmen...
Aspects of twin screw ships semi-empirical maneuvering models
Ocean Engineering, 2012
Simplified mathematical models based upon semi-empirical regression formulae describing forces and moments acting on the hull during manoeuvres are commonly used for the preliminary evaluation of ship steering capabilities. Many semi-empirical regressions have been developed, and are broadly adopted, for the manoeuvrability prediction of single screw slow/medium speed ships. Their application for the study of twin screw vessels (cruise ships, RoRo ferries, megayachts, naval vessels, for which dedicated regression formulae are scarce) manoeuvring capabilities could lead to misleading results. These ships are usually characterised by different hull forms and more complex stern configuration due to the presence of appendages like skegs, shaft lines and brackets, which can strongly affect manoeuvrability behaviour. In this work a novel procedure to properly account for the particular geometric and stern appendage characteristics of these kind of vessels is described. A thorough analysis has been performed on a ship model equipped with 13 different stern appendage configurations and new formulae have been developed in order to describe accurately their influence on ship manoeuvring behaviour.
Uncertainty assessment for ship maneuvering mathematical model
International Shipbuilding Progress, 2015
An 8 DoF ship maneuvering motion model for a twin-propeller twin-rudder high-speed hull form is developed from captive model experiment data available from literatures. The degrees of freedom considered are surge, sway, yaw, roll, rudder rate and propeller rate. Besides maneuvering motion model, variation of port/starboard propeller thrust and torque and port/starboard rudder normal force and rudder torque are also included in the model. An uncertainty analysis computation for the mathematical model is carried out. Uncertainties in the experimental data and the polynomial curve fitting during modeling are included in the computation. It is shown that the mathematical model uncertainty is higher than the experimental uncertainty. Uncertainty is propagated to full-scale zigzag maneuver using the conventional Monte Carlo simulation (MCS) method. The uncertainty analysis results will be useful for further improvement of mathematical model, validation of CFD simulation results of appended hull maneuvering tests, etc. We have also shown the utility of asymmetric operations of the twin-propeller and twin-rudder by carrying out full-scale simulation a zigzag maneuver and showing the variation of the rudder normal force and torque.
9th IFAC Conference on Control Applications in Marine Systems (2013), 2013
Propulsion system can experience large power absorption fluctuations during tight maneuvers. In the case of a turning circle maneuver for a twin-screw ship, the power required by the two shaft lines can be completely different; in case of non conventional propulsion system, like cross-connect configurations, a compromise must be met in order to design a safe control system without affecting dramatically the vessel's maneuvering performance. In this work, a series of free running model tests have been carried out in order to investigate the influence of different propulsion system operation settings on the vessel's maneuvering characteristics.
Theoretical background and application of MANSIM for ship maneuvering simulations
Ocean Engineering, 2019
In this study, a new developed code, MANSIM (MANeuvering SIMulation) for ship maneuvering simulations and its theoretical background were introduced. In order to investigate the maneuverability of any low-speed ship with single-rudder/single-propeller (SPSR) or twin-rudder/twinpropeller (TPTR) configurations, a 3-DOF modular mathematical model or empirical approaches can be utilized in MANSIM. Not only certain maneuvers of ships such as, turning or zigzag but also free maneuver with unlimited number of rudder deflections can be simulated. Input parameters required to solve the equations of motion can be estimated practically by several empirical formulas that are embedded in the software. Graphical user interface of the code was designed simply so that users can perform maneuvering calculations easily. Besides displaying the results such as advance, transfer, tactical diameters etc. on the user interface, simulation results can also be analyzed graphically; thus it is possible to examine the variation of kinematic parameters during simulation. Using the code, maneuverabilities of a tanker ship (KVLCC2) and a surface combatant (DTMB5415) have been investigated and computed results were compared with free running data for validation. It is considered that MANSIM is quite advantageous for parametric studies and it is a valuable tool especially for sensitivity analysis on ship maneuvering. In this context, the effects of variation of hydrodynamic derivatives and rudder parameters on general maneuvering performance of ships were investigated by performing sensitivity analyses. It was found out that linear moment derivatives and rudder parameters are highly effective in maneuvering motion. Another interesting outcome of this study is the identification of the significance of third order coupled derivatives for DTMB5415 hull.