Wyniki wyszukiwania - BazTech

1

Numerical investigation of length to beam ratio effects on ship resistance using ranse method

Le Tat Hien, Nguyen Duy Anh, Tran Ngoc Tu, Hoa Nguyen Thi Ngọc, Ngoc Vu Minh

Polish Maritime Research

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2023

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nr 1

13--24

EN

The paper discusses the length to beam (L/B) ratio effects on ship resistance at three different Froude numbers using unsteady RANSE simulation. First, the JBC ship model was used as an initial hull form for verification and validation of predicted ship resistance results with measured data, and then the influence of the L/B ratio on ship resistance was carried out. Ship hull forms with different L/B ratios were produced from the initial one by using the Lackenby method. The numerical results obtained show the L/B ratio’s effect on ship resistance. Increases of the L/B ratio led to gradual reduction of the total ship resistance and vice versa. Analysis of the changing of the resistance components indicates that the pressure resistance changes are considerably larger than the frictional one. Finally, the paper analyses the difference in the flow field around the hull of the ship with variation of the L/B ratio to fully understand the physical phenomenon in the change of ship resistance at different L/B parameters.

2

Numerical study of effect of trim on performance of 12500DWT cargo ship using RANSE method

Chuan Tran Quoc, Phuong Nguyen Kim, Tu Tran Ngoc, Quan Mai Van, Anh Nguyen Duy, Le Tat-Hien

Polish Maritime Research

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2022

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nr 1

3--12

EN

This paper deals with the results of studying the effect of trim on the performance of series cargo ship 12500DWT in full scale at two operating conditions by using the RANSE method. The Body Force Propeller method is used to simulate a rotating propeller behind the ship. The numerical predicted results at the ballast condition were verified and validated with sea trial data. The ship’s engine power curves for different trim conditions at two operating conditions were carried out to produce a data source to evaluate the effect of trim on the performance of the 12500DWT cargo ship. The results indicate that if the ship operates under optimum trim conditions, this can decrease the ship’s engine power in a range from 2.5 to 4.5% depending on different loading conditions and ship speeds. Finally, the paper also provides detailed differences in flow around the ship due to trim variation to explain the physical phenomenon of changing ship performance.

3

Study on green water of tumblehome hull using dam-break flow and RANSE models

Sun S., Du W., Li H.

Polish Maritime Research

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2017

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S 2

172--180

EN

The tumblehome hull adopts some novelty designs such as low-tumblehome freeboard and wave-piercing bow. The new form design makes the ship have many special hydrodynamic performances. Especially the green water of tumblehome hull is different from that of hulls with flare free board. Green water is a strong nonlinear phenomenon of ship-wave interaction, the variation of free surface of liquid is complicated, and there are still some difficulties to solve green water problems well with numerical simulation method. In this paper firstly the motion responses of the tumblehome hull was calculated based on 3D potential theory, and then the dam-break flow model was used to calculate green water height and pressure distribution. According to the result of numerical simulation, some typical working conditions are chosen for 3D CFD simulation using RANS method. The results of numerical simulation methods are compared with the experimental results measured in towing tank. The influence of different ship form parameters and wave parameters to the green water of tumblehome hull is analyzed, and some regularities of green water on tumblehome hull in regular waves are summarized.

4

Numerical evaluation of the wave pattern for fast ships with taking into account the dynamic trim and sinkage

Kraskowski M.

Polish Maritime Research

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2006

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nr 3

8-16

EN

This paper presents results of the numerical evaluation of the fast container ship's wave pattern, based on the RANSE (Reynolds-Averaged Navier Stokes Equations) method with dynamic trim and sinkage taken into account. Evaluating the ship's running attitude is based on coupling the flow solver with solving the motion equations for the ship hull. The results are presented for four speed values and contain: ship's running attitude (defined by changes of ship draught and trim angle), wave contours and wave profiles in chosen planes. The computed ship's running attitude and wave profiles are compared with the experimental results.