• Title/Summary/Keyword: Model-ship correlation

Search Result 66, Processing Time 0.022 seconds

A Study on Resistance Test of Icebreaker with Synthetic Ice (합성 얼음을 사용한 쇄빙선 저항시험에 대한 연구)

  • Song, Yun-Young;Kim, Moon-Chan;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.44 no.4
    • /
    • pp.389-397
    • /
    • 2007
  • This research describes a framework to compare and analyze the icebreaker(Terry Fox) resistance in pack ice condition between with a refrigerated ice and a synthetic ice. Model tests with a refrigerated ice have been conducted at Institute for Ocean Technology (IOT/NRC) and the tests with a synthetic ice were conducted at Pusan National University towing tank. For the validation of further tests of measurement and accuracy, the open water tests were first carried out with same model ship to compare the test results of both Institutes. Two different size of the wax-type synthetic ice were used and tests were conducted in pack ice of three different concentration ice conditions. The test results show that the difference of resistance between with synthetic and with refrigerated ice becomes larger according to the increase of ship speed. Although the quantity of resistance difference is not so small in high speed range, the present study is predicted to be used as a useful correlation between synthetic and refrigerated ice.

Performance Test and Model-Ship Correlation for a Waterjet Propulsion System (실선 물분사 추진장치 성능시험 및 모형선-실선 상관관계)

  • Jong-Woo Ahn;Chang-Yong Lee;Young-Ha Park;Jong-Ahn Chung;Byung-Hyun Kim
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.35 no.4
    • /
    • pp.11-18
    • /
    • 1998
  • This study describes sea trial tests for a waterjet propulsion system attached in the hybrid super high speed cargo ship named "Narae". A measuring technique of jet velocity, gross thrust and impeller torque for the waterjet system is explained. From the measured data in sea trial test, performance of the waterjet propulsion system is analyzed and compared with model test results of a similar waterjet system which was carried out in 1996. The erective horse power estimated from sea trial tests shows a good agreement with resistance test results of the model ship. The optimum rising height is estimated as 0.75 m, and the overall efficiency of the waterjet system is predicted as 0.315 at 15 knots. Useful data such as the pump performance, the jet efficiency, the losses of inlet duct and nozzle were obtained. Test results show a similar behavior to the model test results.

  • PDF

Current Status and Rate of Change of National Ships by each Ship : Focusing on Passenger ships, Cargo ships, Oil Tankers, Towing and Barges (국적선의 각 선박별 현황과 변동률 : 여객선, 화물선, 유조선, 예선, 부선을 중심으로)

  • Choi, Soo-Ho;Kim, Shin-Joong
    • Journal of Digital Convergence
    • /
    • v.19 no.10
    • /
    • pp.195-202
    • /
    • 2021
  • The purpose of this study is to classify national ships into passenger ships, cargo ships, oil tankers, tugboats, barges, and other ships by use, and compare the rate of change and direction respectively. In this study, a total of 123 monthly data were searched from January 2011 to March 2021 in Statistics Korea's KOSIS "Traffic Logistics => Operating Vessel Statistics => Possesion State of National Vessels". To this end, we calculated the rate of change from the previous month for each ship and performed numerical analysis and model analysis. In the correlation analysis, the Total showed a high relationship in the order of Towing, Barge, Oil, Cargo and Ferry. In the regression analysis, each ship was found to be statistically significant and varied independently of each other. The increase rate was highest in the order of Ferry, Oil, Towing, Barge and Cargo during the last analysis period. In the analysis of Scatter Charts, Towing and Barge showed more than a certain level of synchronization with respect to the Total. The synchronization phenomenon for each ships was calculated to be rather low, indicating that the correlation between each ships was low. However, the correlation between Oil and Towing, Oil and Barge and Towing and Barge is relatively high, indicating a relatively large correlation.

The Effects of Rudder Size on Characteristics of Fluid Flow around Ship's Stern in Manoeuvring Motion (타의 크기가 조종운동시 선미 유동 특성에 미치는 영향)

  • 손경호;김용민
    • Journal of the Korean Institute of Navigation
    • /
    • v.25 no.1
    • /
    • pp.1-9
    • /
    • 2001
  • It is well known that, especially in the case of full-bodied ship, the course stability may become the severest among 4 items of requirement in Interim Standards for Ship Manoeuvrability adopted by IMO in 1993. The purpose of this study is to find some ideas for characteristics of fluid flow pattern around ship's stern in manoeuvring motion with parameter of changes in rudder size. We carried out two kinds of model experiment in obliquely running condition at circulating water channel. One is measurement on straightening effect of incoming flow to rudder and the other is experiment on flow visualization around the gap between rudder and stern-bottom. We discuss the correlation between the flow characteristics around ship's stem and flow straightening effect at rudder from the viewpoint of course stability. As a result, it is clarified that the gap between rudder and stern-bottom plays an important role in course stability of full-bodied ship. It is pointed out that there is quite a possibility of bad course stability as the gap between rudder and stern-bottom decreases.

  • PDF

Hydrodynamic Hull Form Design Using an Optimization Technique

  • Park, Dong-Woo;Choi, Hee-Jong
    • International Journal of Ocean System Engineering
    • /
    • v.3 no.1
    • /
    • pp.1-9
    • /
    • 2013
  • A design procedure for a ship with minimum resistance had been developed using a numerical optimization method called SQP (Sequential Quadratic Programming) combined with computational fluid dynamics (CFD) technique. The frictional resistance coefficient was estimated by the ITTC 1957 model-ship correlation line formula and the wave-making resistance coefficient was evaluated by the potential-flow panel method with the nonlinear free surface boundary conditions. The geometry of the hull surface was represented and modified by B-spline surface modeling technique during the optimization process. The Series 60 ($C_B$=0.60) hull was selected as a parent hull to obtain an optimized hull that produces minimum resistance. The models of the parent and optimized hull forms were tested at calm water condition in order to demonstrate the validity of the proposed methodolgy.

Fundamental Study for the Development of an Optimum Hull Form (최적선형개발에 대한 기초연구)

  • 최희종;전호환;정석호
    • Journal of Ocean Engineering and Technology
    • /
    • v.18 no.3
    • /
    • pp.32-39
    • /
    • 2004
  • A design procedure for a ship with minimum total resistance has been developed using a numerical optimization method called SQP(sequential quadratic programming) to search for different optimal hull forms. The frictional resistance has been estimated using the ITTC 1957 model-ship correlation line formula, and the wave resistance has been evaluated using a potential-flow panel method that is based on Rankine sources with nonlinear free surface boundary conditions. The geometry of a hull surface has been modified using B-spline surface patches, during the whole optimization process. The numerical analyses have been carried out for the modified Wilgey hull at three different speeds (Fn=0.25, 0.316, 0.408), and the calculation results were compared.

Statistical Characteristics of Pollutants in Sterm Flow (하천오염인자의 통계적 특성)

  • 황임구;윤태훈
    • Water for future
    • /
    • v.14 no.4
    • /
    • pp.19-26
    • /
    • 1981
  • The auto-and cross-correlation function, power spectrum, coherence function and Markov model are applied to investigate the statistical characteristics of discharge and each factor of water quality and the interrelation-ship between the variation of discharge and water quality factors. The analysis of discharge, dissolved oxygen and electric conductivity, which were only obtainable data at the Indogyo gagining station in the downstream of the Han River, clearly showed that they hace distinct period of 12 months and three different periods of 6, 4 and 3 months weaker than the former. The cross-correlation between the discharge and water quality(DO, COND) is rather weak and the crosscorrelation function has its peak at lag one. It is considered therefrom that the variation of discharge behaves on water quality facotrs with one day's difference. In the examination of linear regression model for the serial generation and predictive measures, discharge series is fit to first and second order Markov model and DO, COND to first order Markov model.

  • PDF

A Study of a Correlation between Experiments and Calculations of Pressure Fluctuation on Hull Surface (선체 변동 압력에 관한 실험과 이론의 비교 연구)

  • Moon-Chan Kim;Ki-Sup Kim;In-Haeng Song
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.33 no.1
    • /
    • pp.19-26
    • /
    • 1996
  • An experimental and computational study of the pressure fluctuation induced by a propeller on a hull surface was carried out with three ship models and seven model propellers. The fluctuation of pressure on a flat plate was measured at KRISO cavitation tunnel and calculated by a panel and lifting surface method(XForShip code). To extend the measurement data on the flat plate into that on complex hull forms, the correction factor was determined as a ratio of the solid boundary factor(SBF). The computation of pressure fluctuation around complex hull forms was also performed to make the full scale prediction and compared with the corrected experimental data. The calculated values agreed well with the compensated experimental data and it was found that the correction factor was about 0.65-0.7.

  • PDF

Study on the procedure to obtain an attainable speed in pack ice

  • Kim, Hyun Soo;Jeong, Seong-Yeob;Woo, Sun-Hong;Han, Donghwa
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • v.10 no.4
    • /
    • pp.491-498
    • /
    • 2018
  • The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

Prediction of Barge Ship Roll Response Amplitude Operator Using Machine Learning Techniques

  • Lim, Jae Hwan;Jo, Hyo Jae
    • Journal of Ocean Engineering and Technology
    • /
    • v.34 no.3
    • /
    • pp.167-179
    • /
    • 2020
  • Recently, the increasing importance of artificial intelligence (AI) technology has led to its increased use in various fields in the shipbuilding and marine industries. For example, typical scenarios for AI include production management, analyses of ships on a voyage, and motion prediction. Therefore, this study was conducted to predict a response amplitude operator (RAO) through AI technology. It used a neural network based on one of the types of AI methods. The data used in the neural network consisted of the properties of the vessel and RAO values, based on simulating the in-house code. The learning model consisted of an input layer, hidden layer, and output layer. The input layer comprised eight neurons, the hidden layer comprised the variables, and the output layer comprised 20 neurons. The RAO predicted with the neural network and an RAO created with the in-house code were compared. The accuracy was assessed and reviewed based on the root mean square error (RMSE), standard deviation (SD), random number change, correlation coefficient, and scatter plot. Finally, the optimal model was selected, and the conclusion was drawn. The ultimate goals of this study were to reduce the difficulty in the modeling work required to obtain the RAO, to reduce the difficulty in using commercial tools, and to enable an assessment of the stability of medium/small vessels in waves.