Evaluation of Planing Craft Maneuverability Using Mathematical Modelling (original) (raw)
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2006
As in many coastal and estuary areas, navigation to and in the Belgian harbours takes place in environmental and operational conditions which differ from the design conditions of seagoing ships: water depth to draft ratios vary between 2.0 and 1.1 which means that the under keel clearance is often restricted to 10% of the ship’s draft. In addition, low ship velocities have to be considered as manoeuvring in harbour areas is characterised by a wide range of speed – propeller rpm combinations. Based on the results of captive model tests executed in the Towing Tank for Manoeuvres in Shallow Water (co-operation Flanders Hydraulics Research – Ghent University, Antwerp, Belgium) with a 6000 TEU containership and the tanker Esso Osaka, an optimized test program has been developed for the determination of a mathematical manoeuvring model in laterally unrestricted water. Contrary to deep water and service speed the selected test types and test parameters will influence the measured contribut...
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Prediction of the maneuvering characteristics of a ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as a direct simulation of the standard maneuvers with the free running model, which gives the most accurate results but is also the least affordable, as it requires a very large tank or natural lake, as well as the complex equipment of the model. Alternatively, a captive model test can be used to identify the hydrodynamic characteristics of the hull, which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt to develop a computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses pre...
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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.
Applied Ocean Research, 2019
The turning circle and zigzag maneuvering performance of surface combatant, DTMB 5415 have been investigated by using system-based method. Unsteady Reynolds averaged Navier Stokes (URANS) approach is utilized to estimate hydrodynamic derivatives and hull-propeller-rudder interactions. DTMB 5415 is a twin-propeller / twin-rudder ship and there are some studies on the derivation of maneuvering coefficients in the literature but none of them took into account the propeller and rudder forces. In this study, static drift, pure yaw, combined yaw and drift, self-propulsion and rudder tests of DTMB 5415 hull have been simulated in calm and deep water condition. Bare hull PMM simulations were carried out for a fixed Froude number of = 0.28, while the simulations related to rudder and propeller were performed at = 0.25. Computational results were used by MMG (Maneuvering Modeling Group) model to estimate the maneuvering performance of the ship. Hydrodynamic derivatives from numerically generated forces and moment data were obtained by single-run and multiple-run methods. The results from both methods were tested in an in-house maneuvering simulation code (MANSIM) that solves for ship motions and they were compared with computed turning circle and zigzag maneuvering performances. Although it is known a priori that the multiplerun method would give better solution in overall, it was found that the single-run method can be a good alternative in some specific cases. For the zigzag and turning circle tests, the results from singlerun method were found satisfactory when correct PMM test conditions were adopted.
2020
Numerically modeling a free-running ship with an operational steering system provides a direct procedure to evaluate whether a ship has good maneuverability. However, there are great challenges due to the complexity of the flow field and the interaction between hull, moving rudders and rotating propellers. Thus, it is essential to find a reliable approach to estimating the maneuvering performance of ship. In the present paper, unsteady Reynold-Averaged Navier-Stokes (RANS) and Delayed Detached Eddy Simulation (DDES) methods are used to investigate the behavior of different models for predicting ship maneuverability. An inhouse solver, naoe-FOAM-SJTU is applied to simulate a free-running ship while maneuvering. A fully appended version of the ONR Topside Series Tumblehome hull form is used for all of the computations. Standard 20/20 zigzag maneuvers in calm water are simulated using different numerical models. Predicted results including overshoot angles, 6-DoF motions, and hydrodyna...
2003
Most formulations of mathematical modelling of ship manoeuvres in shallow water discussed in literature are based on expressions for the deep water case. Several usual and unusual phenomena occurring during manoeuvres at limited under keel clearance (10% to 50%) are not considered. A tabular model for the hull forces is proposed, taking the shallow water condition as starting point, with the intention to cover wide ranges of kinematical parameters so that a great variety of manoeuvres can be simulated. The implementation of the mathematical model is based on captive model tests with 4 m models of the tanker Esso Osaka and a fourth generation container carrier. The experimental program consists of well-known, classical PMM test types combined with alternative tests. Preliminary guidelines are formulated for the selection of test parameters, taking account of their influence on the hydrodynamic coefficients.
Analysis of a Model for Ship Maneuvering
Information and Computation/information and Control, 2011
We analyze numerically and theoretically steady states and bifurcations in a model for ship maneuvering provided by MARIN, and in a simplified model that combines rudder and propeller into an abstract 'thruster'. Steady states in the model correspond to circular motion of the ship and we compute the corresponding radii. We non-dimensionalize the models and thereby remove a number of parameters, so that, due to a scaling symmetry, only the rudder (or thruster) angle remains as a free parameter.
2006
The Flemish waterways authorities are permanently concerned about safety of navigation to the Flemish harbours in order to maintain their present position in the European shipping market. Special attention is paid to the effect of the constant growth of ship dimensions, especially in the container trade, on the safety of shipping traffic. Access to and manoeuvring in harbours are characterised by a great diversity of kinematical and control parameters. In 2004-2005 a captive model test program has been executed with a 4.3 m model of an 8000 TEU containership (scale 1:81) combining three distinguished drafts and three under keel clearances from deep to very shallow water. This test program covering all possible combinations of ship velocities and propeller telegraph positions has been used to evaluate hull, propeller and rudder forces to be incorporated in a manoeuvring simulation model applicable in the four quadrants of operation. The influence of combinations of draft and under ke...