• Title, Summary, Keyword: Circulating water channel

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Depressurized Circulating Water Channel Design Using CFD (수치 해석을 이용한 감압 회류 수조 설계)

  • 부경태;조희상;신수철
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.4
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    • pp.22-29
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    • 2003
  • New high-speed depressurized circulating water channel was designed by using the CFD code. Flow in the channel has free surface and pressure in the test section can be depressed. In this study, Flow separation and bubble occurrence were considered in designing the contraction nozzle shape for better flow uniformity Tn the test section. To supplement velocity defect due to the free surface, nozzle injection system more effective in high-speed flow was installed instead of drum system. Necessary power and injection techniques were proposed. And guide vane arrangement was analyzed to reduce the flow resistance and keep quiet free surface from ´surging´. Wave absorber was devised to reduce the wave resistance and to prevent the entrainment of air to the diffuser.

Correlative Experimental Study Between The Results of Circulating Water Channel and Towing Tank Tests

  • Lee, Kwi-Joo;Kim, Kyoung-Hwa;Isaacs, Karl Antony
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.70-75
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    • 2003
  • Model tests using 2.0m model of the series 60 form ($C_{b}$ = 0.6) were carried out in the Circulating Water Channel(CWC) in the Chosun University(CU, Korea) for the purpose of a correlative study with Towing Tank(TT). Resistance, propeller open water, self propulsion, and wake survey tests were carried out and the results were extrapolated to the ship scale. These results were compared with the extrapolated ship values based on the model test of 7.0m model in the TT at the Korea Research Institute of Ships and Ocean Engineering (KRISO, Korea). The CWC test results were correlated with the results of the towing tank tests.

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Correlative Experimental Study Between The Results of Circulating Water Channel and Towing Tank Tests (회류수조와 예인수조 시험결과의 상호관계의 실험적 연구)

  • Lee, K.J.;Ra, Y.K.
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.4
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    • pp.37-45
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    • 2003
  • Model tests using 2.0m model of the series 60 form( $C_{b}$= 0.6) were carried out in the Circulating Water Channel (CWC) in the Chosun University (CU, Korea) for the purpose of a correlative study with Towing Tank (TT). Resistance, propeller open water, self propulsion and wake survey tests were carried out and the results were extrapolated to the ship scale. These results were compared with the extrapolated ship values based on the model test of 7.0m model in the TT at the Korea Research Institute of Ships and Ocean Engineering (KRISO, Korea). The CWC test results were correlated with the results of the towing tank tests.s.

Design and Performance Analysis of a Small Circulating Water Channel for Ocean Engineering (해양공학용 소형 회류수조 설계 및 성능분석)

  • Yim, Young-Bae;Jeong, Uh-Cheul;Park, Chan-Won;Hong, Ki-Sup
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.198-202
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    • 2003
  • A small circulating water channel (CWC) for experiments ocean engineering is designed and made through the co-work of a company, MESTEC, and a college, Inha Technical Research Institute. General function of the elements of CWC are explained. The velocities in the test section are measured and analysed to estimate the performance of the CWC. The result of the velocity distribution is acceptable for experiments of ocean engineering.

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Bubble Wake Measurement by Acoustic Bubble Spectrometer Generated by Planing Hull at Circulating Water Channel (회류수조에서의 ABS에 의한 활주선 후류 기포항적계측)

  • Shin, Myung-Soo;Moon, Il-Sung;Nah, Young-In;Park, Jong-Chun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.1
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    • pp.55-61
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    • 2011
  • This paper presents bubble wake measurement results generated by the planing hull. The bubble was generated by SNAME TMB model(No. 4876) with hard chine at the CWC(Circulating Water Channel). ABS(Acoustic Bubble Spectrometer) was used to measure bubble wake measurement. The manufactured model is one meter in length and uniform velocity to generate the bubble at CWC is 3m/s, relatively higher speed than conventional hull form. Measurements were performed successfully and measured results show well the general characteristics of bubble wake generated by planing hull. Furthermore, experimental equations are proposed for the practical use.

A Study on Biased Flow Region Using PIV Technique (PIV기법을 이용한 편향흐름 발생영역 규명)

  • Na, Jeong-Heon;Kwon, Sun-Hong
    • Journal of Ocean Engineering and Technology
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    • v.13 no.1
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    • pp.105-112
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    • 1999
  • This research is an experimental investigation of the region of the Biased Flow. This experiment was carried out in a circulating water channel, and the results are analyzed by using the PIV technique. The results are presented in velocity vector field, velocity contour and vorticity contour. The results were compared with those of Zdravkovich which were carried out in a wind tunnel. These results will be very useful to verify numerical codes.

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A Study on Manoeuvring Motion Characteristics of Manta-type Unmanned Undersea Vehicle (Manta형 무인잠수정의 조종운동 특성에 관한 연구)

  • Bae, Jun-Young;Sohn, Kyoung-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.2
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    • pp.114-126
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    • 2009
  • The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz and French 2000, Sirmalis et al. 2001). In order to evaluate manoeuvring motion characteristics of MUUTV, numerical simulation technique has been utilized. Previous mathematical model on manoeuvring motion of MUUTV(Sohn et al. 2006) is basically adopted. Result of static experiment carried out in circulating water channel and a part of NSRDC standard model(Feldman 1979) on rotational mode are supplemented. Some of the hydrodynamic derivatives are obtained from model experiment in circulating water channel and the rest of them are estimated.

Planar Motion Mechanism Test of the Mobile Harbor Running in Design Speed in Circulating Water Channel

  • Yoon, Hyeon-Kyu;Kang, Joo-Nyun
    • Journal of Navigation and Port Research
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    • v.34 no.7
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    • pp.525-532
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    • 2010
  • Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.

Performance Evaluation of Ocean Small Hydropower Plant by Analyzing Water Level and Flow Rate of Circulating Water (방류수의 수위 및 유량 분석을 통한 해양 소수력 성능평가)

  • Kang, Keum-Seok;Kim, Ji-Young;Ryu, Moo-Sung
    • New & Renewable Energy
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    • v.5 no.3
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    • pp.32-39
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    • 2009
  • The Samcheonpo ocean small hydropower plant (SHP) has a special feature of using marginal hydraulic head of circulating water system of fossil fuel power plant as a power source and having the characteristics of general hydropower generation and tidal power generation as well. Also, it contributes to reducing green house gases and developing clean energy source by recycling circulating water energy otherwise dissipated into the ocean. The efficiency of small hydropower plant is directly affected by effective head and flow rate of discharged water. Therefore, the efficiency characteristics of ocean hydropower plant are analyzed with the variation of water level and flow rate of discharged water, which is based on the accumulated operation data of the Samcheonpo hydropower plant. After the start of small hydropower plant operation, definite rise of water level was observed. As a result of flow pattern change from free flow to submerged flow, the instability of water surface in overall open channel is increased but it doesn't reach the extent of overflowing channel or having an effect on circulation system. Performance evaluation result shows that the generating power and efficiency of small hydropower exceeds design requirements in all conditions. Analysis results of CWP's water flow rate verify that the amount of flowing water is measured less and the highest efficiency of small hydropower plant is achieved when the effective head has its maximum value. In conclusion, efficiency curve derived from water flow rate considering tidal level shows the best fitting result with design criteria curve and it is verified that overall efficiency of hydropower system is satisfactory.

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Changes in Dynamic Characteristics of Monopile-Type Offshore Structures According to Tidal Environments and Boundary Conditions (다양한 조류 환경 및 경계 조건에 따른 모노파일형 해상구조물의 동특성 변화 분석)

  • Jung, Byung-Jin;Park, Jong-Woong;Yi, Jin-Hak;Park, Jin-Soon
    • Journal of Ocean Engineering and Technology
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    • v.28 no.4
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    • pp.261-267
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    • 2014
  • Because a change in the natural frequencies of a structure indicates structural health problems, monitoring the natural frequencies crucial. Long-term measurement for the Uldolmok tidal current power plant structure has shown that its natural frequencies fluctuate with a constant cycle twice a day. In this study, lab-scale tests to investigate the causes of these natural frequency fluctuations were carried out in a circulating water channel. Three independent variables in the tests that could affect the fluctuation of the natural frequencies were the water level, current velocity, and boundary condition between the specimen and the bottom of the circulating water channel. The experimental results were verified with numerical ones using ABAQUS. It was found that the fluctuation of the natural frequencies was governed by a decrease in stiffness due to the boundary condition much more than the effect of added mass. In addition, it was found that the natural frequency would decrease with an increase in the tidal current velocity because of its nonlinearity when the boundary condition was severely deteriorated due to damage.