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The effect of the stern wedge length and height on the drag and trim of a chine-planing hull

Ghassemi Mohammad A., Ghadimi Parviz, Sajedi Sayyed Mahdi

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2021

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nr 67 (139)

39--52

EN

This paper examines the effect of the stern wedge length and height on the drag and trim of a chine-planing hull in calm water. To this end, fluid flow was simulated by Star-CCM+ software by applying an overset mesh and k-ε turbulent model. The finite volume method was used to discretize the fluid domain, and the fluid volume was utilized to capture the generated free surface. The considered model is a prismatic planing hull with a deadrise angle of 24°, a mass of 86 kg, a length (L) of 2.64 m, and a beam (B) of 0.55 m. For validation, the numerical results of drag and trim were compared against experimental data, which displayed good compliance. Subsequently, the hydrodynamic performance of the planing hull was investigated, and the wedge effect was assessed. The stern wedge was located at the bottom and near the aft perpendicular to the hull to facilitate a moderate distribution. Various wedge lengths of 0.2B, 0.5B, and B at two different heights of 5 mm and 10 mm were examined to assess the hydrodynamic performance of the hull at various speeds. The trim angle, resistance, water surface elevation, porpoising, roster tail, and the stern and bow were computed and analyzed. Based on the numerical results, it was concluded that when the wedge length increased, the drag and trim were reduced. It was also concluded that the best wedge for a vessel with desirable wake generation is one with a length of 0.2B and a height of 5 mm.

2

А Меаsuring Method for Gyro-Free Determination of the Parameters of Moving Objects

Dichev D., Koev H., Bakalova T., Louda P.

Metrology and Measurement Systems

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2016

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Vol. 23, nr 1

107--118

EN

The paper presents a new method for building measuring instruments and systems for gyro-free determination of the parameters of moving objects. To illustrate the qualities of this method, a system for measuring the roll, pitch, heel and trim of a ship has been developed on its basis. The main concept of the method is based, on one hand, on a simplified design of the base coordinate system in the main measurement channel so as to reduce the instrumental errors, and, on the other hand, on an additional measurement channel operating in parallel with the main one and whose hardware and software platform makes possible performing algorithms intended to eliminate the dynamic error in real time. In this way, as well as by using suitable adaptive algorithms in the measurement procedures, low-cost measuring systems operating with high accuracy under conditions of inertial effects and whose parameters (intensity and frequency of the maximum in the spectrum) change within a wide range can be implemented.

3

Monitoring and analysis of the performance data of a RO-PAX ship in the perspective of energy efficiency

Galli A. M., Gualeni P., Stranieri G., Qualich S., Cusano G.

Polish Maritime Research

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2014

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nr 4

18--26

EN

The rising cost of fuel, the more and more severe international standards and a growing awareness of the environmental impact of pollutant emissions have led energy efficiency to become a theme of great interest in the marine sector. The strategy for increasing energy efficiency may refer both to the consumption reduction and to the increase of energy recovery systems. This need turns out in monitoring and control strategies for energy processes on board. Monitoring information is recorded and stocked in a database, that needs to be analyzed to find out patterns in large data sets. A huge amount of data, from a RO-PAX ship, has been analyzed in order to gain a further insight into ship performances. Improvements in ship energy performances could be reached with an intense study of the historical data of the vessel attitude.

4

Stabilizacja kąta przegłębienia pojazdu podwodnego przenoszącego ładunek

Szymak P.

Pomiary Automatyka Robotyka

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2007

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R. 11, nr 2

PL

W przypadku wykorzystania manipulatora pojazdu podwodnego do przenoszenia różnego rodzaju ładunków może być zaobserwowany efekt niepożądanego przegłębienia robota, co ma niekorzystny wpływ na proces sterowania jego ruchem. Dla potrzeb regulacji kąta przegłębienia pojazdu podwodnego przebadano regulatory konwencjonalne i rozmyte, dostrajane przy użyciu metod klasycznych oraz metod sztucznej inteligencji.

EN

In the case of use an underwater vehicle’s manipulator to transfer different kind of loads, it can be observed an undesirable robot’s trim effect, what has disadvantageous effect on robot’s movement control. For the purpose of control of an underwater vehicle’s trim, it has been examined conventional and fuzzy controllers, which were tuned with assistance of classical and artificial intelligence methods.

5

Calculation of ship sinkage and trim in deep water using a potential based panel method

Tarafder M. S., Khalil G. M.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 2

401-414

EN

The present work is an extension of Morino's panel method for the calculation of wave-making resistance of ships with special reference to sinkage and trim. The body boundary is linearized about the undisturbed position of the body and the free surface is linearized about the mean water level by the systematic method of perturbation. The surfaces are discretized into flat quadrilateral elements and the influence coefficients are calculated by Morino's analytical formula. Dawson's upstream finite difference operator is used in order to satisfy the radiation condition. The sinkage and trim of a ship are computed by equating the vertical force and pitching moment to the hydrostatic restoring force and moment. The present method has been applied to the Series 60 hull for different Froude numbers and is found to be efficient for evaluating the flow field, wave pattern and wave-making resistance in deep water.