• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.356-365
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• 2014

This paper is the second in a series and aims to build a high-fidelity mathematical model for a propeller-driven airplane using the propeller's aerodynamics and inertial models, as developed in the first paper. It focuses on aerodynamic models for the fuselage, the main wing, and the stabilizers under the influence of the wake trailed from the propeller. For this, application of the vortex lattice method is proposed to reflect the propeller's wake effect on those aerodynamic surfaces. By considering the maneuvering flight states and the flow field generated by the propeller wake, the induced velocity at any point on the aerodynamic surfaces can be computed for general flight conditions. Thus, strip theory is well suited to predict the distribution of air loads over wing components and the viscous flow effect can be duly considered using the 2D aerodynamic coefficients for the airfoils used in each wing. These approaches are implemented in building a high-fidelity mathematical model for a propeller-driven airplane. Flight dynamic analysis modules for the trim, linearization, and simulation analyses were developed using the proposed techniques. The flight test results for a series of maneuvering flights with a scaled model were used for comparison with those obtained using the flight dynamics analysis modules to validate the usefulness of the present approaches. The resulting good correlations between the two data sets demonstrate that the flight characteristics of the propeller-driven airplane can be analyzed effectively through the integrated framework with the propeller and airframe aerodynamic models proposed in this study.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.15-21
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• 2006

Recently, the attention to large container ships whose size is greater than 10,000 TEU container ship has been increased due to their increasing demand. The large container ship has twin skegs because of the engine capacity and large beam-draft ratio. In this paper, the maneuvering characteristics of a container ship with twin skegs were investigated through 4DOF(four degree of freedom) HPMM(Horizontal Planar Motion Mechanism) test and computer simulation. A mathematical model for maneuvering motion with 4DOF of twin skegs system was established to include effects of roll motion on the maneuvering motion. And to obtain roll-coupling hydrodynamic coefficients of a container ship, 4DOF HPMM system of MOERI which has a roll moment measurement system was used. HPMM tests were carried out for a 12,000 TEU class container ship with twin skegs at scantling load condition. Using the hydrodynamic coefficients obtained, simulations were made to predict the maneuvering motion. Rudder forces of twin-rudders were measured at the angles of drift and rudder. The neutral rudder angles with drift angles of ship was quite different with those of single skeg ship. So other treatment of flow straightening coefficient $\gamma_R$ was used and the simulation results was compared with general simulation result. The treatment of experimental result at static drift and rudder test was very important to predict the maneuverability of a container ship with twin skegs.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.161-169
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• 2017

Recently, ship owners have been requiring the assessment of the maneuverability of twin-screw ships under mechanical failures. Because this kind of assessment has not yet been conducted, it is necessary to study the types of machinery failures that can significantly affect the maneuverability of a ship, and to construct a procedure to simulate the maneuvering behavior under such failures. In this paper, the sole focus is the steering system failure from among the variety of failure types, and the maneuvering behavior of the ship under the single rudder failure is simulated for an investigation of the unique characteristics. First, the mathematical model for the twin-screw container ship is verified by comparing the simulated results for the $35^{\circ}$ turning test, $10^{\circ}/10^{\circ}$ zigzag test, and $20^{\circ}/20^{\circ}$ zigzag test under the normal operating condition with those obtained from free running model tests. After the IMO maneuvering tests are additionally simulated under the single rudder failure, the results are reviewed to investigate the maneuvering characteristics that are due to the failure. Further, the $35^{\circ}/35^{\circ}$ zigzag test and the $35^{\circ}$ turning test are simulated to additionally investigate the effects of the single rudder failure on the steering and turning abilities.

• Journal of the Korean Institute of Navigation
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• v.24 no.5
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• pp.397-403
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• 2000

Since very large and high-speed ships have been appeared in marine transportation from 1970s, these ships with poor maneuverability have made large-scale accidents frequently all over the world. The IMO(International Maritime Organization) recommended that ship designers should evaluate various maneuvering performance at initial stage and serve them to ship operators when they deliver a new ship. Meantime, it is expected that ships with large and wide superstructure would have poor maneuverability when they are affected by strong wind. Therefore, car carrier ship with large superstructure was selected to confirm how the ship responds to the external wind forces in this paper. The lateral and transverse projected areas above the water level were considered and ship behaviors were checked by change of rudder angles under severe wind conditions of different directions. In addition, hydrodynamic derivatives and coefficients were predicted from ship particulars and numerical calculations were carried out with the mathematical model of low speed maneuvering motions.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.154-161
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• 2014

Naval ships have hull appendages which are more exposed to the outside because of its small block coefficient compared with commercial ships. These exposed hull appendages like skeg, strut and shaft line affect the maneuverability of a ship. The effect of hull appendages has considered at initial design stage to estimate more accurate maneuverability. In this paper, sensitivity analysis is used to analyze the effect on maneuverability by hull appendages. 3 DOF maneuvering equations based on Mathematical Modelling Group (MMG) model are used and propeller & rudder model are modified to reflect the characteristics of twin propeller & twin rudder. Numerical maneuvering simulations (Turning test, Zig-zag test) for benchmark naval vessel, David Taylor Model Basin (DTMB) 5415 are performed. In every simulation, it is calculated that stability indices and maneuverability characteristics (Tactical Dia., Advance, 1st Overshoot, Time of complete cycle) with respect to the parameters (area times lift coefficient slope, attachment location) of hull appendages. As a result, two regression formulas are established. One is the relation of maneuverability characteristics and stability indices and the other is the relation of stability indices and hull appendages.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.589-596
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• 2008

In this paper, Artificial Neural Network(ANN) is applied to automatic berthing control for a ship. ANN is suitable for a maneuvering such as ship's berthing, because it can describe non-linearity of the system. Multi-layer perceptron which has more than one hidden layer between input layer and output layer is applied to ANN. Using a back-propagation algorithm with teaching data, we trained ANN to get a minimal error between output value and desired one. For the automatic berthing control of a containership, we introduced low speed maneuvering mathematical models. The berthing control with the structure of 8 input layer units in ANN is compared to 6 input layer units. From the simulation results, the berthing conditions are satisfied, even though the berthing paths are different.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.343-352
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• 2018

In this study, a motion control problem for the vessels towed by tugboats or towing ships on the sea is considered. The towed vessel looks like the barge ship, which is used for many purposes. In these vessels, basically, the power propulsion system is not installed but just towed by a towing vessel such as tugboats with ropes and wires. It means that the motions of towed vessel are basically dependent on the tracking route of towing boat. Therefore, in some cases, undesirable and unpredictable motions may be made by environmental factors such as wave, wind attack and so on. As a result, a collision accident with others may occur during maneuvering situation. Based on these facts, the authors try to encourage the steering performance of the towed vessel by using controllable rudders without any propulsion system. In this study, especially, a controllable vessel with three rudders is considered, and a mathematical model is induced for the future study. The model is described as surge, sway motion and inertia moment by following the general representation method for the surface ship.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.204-214
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• 2017

Recently, ship owners have been requiring the assessment of the maneuverability of a twin-screw ship under machinery failures. In this paper, we are only focused on the propulsion failure among propulsion failure, power supply failure, steering system failure etc. First of all, the mathematical model for the twin-screw 174K LNGC is verified by comparing the simulated results for $35^{\circ}$ turning test, $10^{\circ}/10^{\circ}$ zigzag test and $20^{\circ}/20^{\circ}$ zigzag test under normal operating condition and those obtained from free running model tests. And, sea trial results of 216K LNGC under single propeller failure are compared with those of 174K LNGC under identical condition to verify the proposed method to predict maneuverability under single propeller failure. After the straight line maneuver is simulated under the single propeller failure, the speed and equilibrated heading and rudder deflection angles at steady state are predicted. After the IMO maneuvering tests are simulated under the single propeller failure, the results are reviewed to investigate the maneuvering characteristics due to the failure.

• Journal of Navigation and Port Research
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• v.36 no.9
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• pp.707-714
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• 2012

Recently, tug boats are widely used for towing a barge which transports building materials, a large block of a ship, offshore crane, and so on. In order to simulate the dynamics of the coupled towing system correctly, the dynamics of the towline should be well modeled. In this paper, the towline was modeled as the multiple finite elements, and each element was assumed as a rigid cylinder which moves in five degrees of freedom except roll. The external tension and its moment acting on each element of the towline were modeled depending on the position vector's direction. Tugboat's motion was simulated in six degrees of freedom where wave and current effects were included, and towed barge was assumed to move in the horizontal plane only. In order to confirm the mathematical models of the coupled towing systems, standard maneuvering trials such as course changing maneuver, turning circle test and zig-zag test were simulated. In addition, the same trials were simulated when the external disturbances like wave and current exist. As the result, it is supposed that the results might be qualitatively reasonable.

• Journal of Drive and Control
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• v.11 no.3
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• pp.7-13
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• 2014

Everyday about 90% of cargos are delivered by ships, and thousands of vessels enter and depart the international container harbors such as Shanghai, Singapore, Hong Kong, Busan, Rotterdam, etc. Maneuvering at harbor is known as the most sophisticated and difficult procedure, because the effectiveness of actuators during low speed berthing is reduced. In this paper, a new berthing method is discussed. Tugboats are combined with damper systems to ensure safe berthing. A mathematical model describing the interaction between unactuated ship, tugboats and damper systems is presented. An optimal controller is designed to maneuver the ship without oscillation and overshoot. MCL (Marine Cybernetics Lab) model ship is used to evaluate the efficiency of the proposed approach through MatLab simulation.