PIV를 이용한 회류수조의 유속 분포 교정에 관한 연구

서성부(Sung bu Suh),정광효(Kwang Hyo Jung) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.4

This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flaw accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

Performance of a model fish cage with copper-alloy net in a circulating water channel and wave tank

Cha, Bong-Jin,Lee, Gun-Ho Elsevier 2018 Ocean engineering Vol.151 No.-

<P><B>Abstract</B></P> <P>This study was aimed at establishing the load on of a circular fish cage with a chain-linked copper-alloy net under the action of ocean currents and waves. The test cage that was used for this purpose was a 1/15 scaled-down model of a real fish cage presently installed in the coastal area of Korea. The deformation and mooring line load of the model cage were observed under different current speeds of 0, 20, 40, 60, and 80 cm/s in a circulating water channel. The mooring line load and its pattern were also examined with respect to the gap between the cage and the supporting buoy (0 (no buoy), 0.5, 1, 1.5, and 2 m, respectively) under the action of a 0.15-m-high wave in the wave tank. Although the volume of the cage hardly changed, the mooring line load exponentially increased with increasing current speed. The addition of the supporting buoy to the cage decreased the maximum load and changed the loading pattern, with the peak load apparently reduced to less than half. The tank test observations were reproduced by computer simulation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Copper-alloy-net cage performance under current and wave action was investigated. </LI> <LI> Cage with copper alloy net volume slightly decreased with increasing current speed. </LI> <LI> Cage with copper alloy net load exponentially increased with increasing current speed. </LI> <LI> The peak of load on the mooring was distributed more than 2 peaks by surface buoy. </LI> <LI> Use of surface buoy reduced load on mooring line of cage with copper alloy net. </LI> </UL> </P>

대각도 받음각을 갖는 무인잠수정에 작용하는 동유체력 특성에 관한 실험적 연구

배준영(Jun-Young Bae),김정중(Jeong-Jung Kim),손경호(Kyoung-Ho Sohn) 한국항해항만학회 2011 한국항해항만학회지 Vol.35 No.3

회류수조에서의 대각도 정적(static) 모형실험을 통해 Manta형 무인잠수체에 작용하는 동유체력을 측정하였으며, 동유체력에 미치는 Reynolds수의 영향을 고찰하였다. 이를 위해 동유체력을 cross-flow drag과 양력(lift force)으로 성분 분석을 하였으며, 양력 성분에는 Reynolds수의 영향을 무시하고, cross-flow drag 성분에만 Reynolds수의 영향을 고려하였다. 그 후 이들 두 성분을 다시 합성함으로써 실물 무인잠수정에 작용하는 동유체력의 추정 기법을 제시하였다. The authors adopt the Unmanned Undersea Vehicle(UUV), the shape of which is like a manta. They call here it Manta UUV. Manta UUV has been designed from the similar concept of the UUV called Manta Test Vehicle(MTV), which was originally built by the Naval Undersea Warfare Center of USA(Lisiewicz and French, 2000; Simalis et al., 2001; U.S. Navy, 2004). The present study deals with the effect of Reynolds numbers on hydrodynamic forces acting on Manta UUV at large angles of attack. The large angles of attack cover the whole range of 0 to ± 180 degrees in horizontal plane and in vertical plane respectively. Static test at large attack angles has been carried out with two Manta UUV models in circulating water channel. The authors assume that the experimental results of hydrodynamic forces (lateral force, yaw moment, vertical force and pitch moment) are analyzed into two components, which are lift force component and cross-flow drag component. First of all, Based on two dimensional cross-flow drag coefficient at 90 degrees of attack angle, the cross-flow drag component at whole range of attack angles is calculated. Then the remainder is assumed to be the lift force component. The only cross-flow drag component is assumed to be subject to Reynolds number.entstly the authors suggest the methodology to predict hydrodynamic derivertives acting on the full-scale Manta UUV.

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

Yoon, Hyeon-Kyu,Kang, Joo-Nyun Korean Institute of Navigation and Port Research 2010 한국항해항만학회지 Vol.34 No.7

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.

진주만의 해수순환 구조

김차겸(Kim, Cha-Kyum),이종태(Lee, Jong-Tae),장호식(Jang, Ho-Sik) 한국해안해양공학회 2010 한국해안해양공학회 논문집 Vol.22 No.4

진주만에서 계절별 해수순환구조의 특성을 해석하기 위해 진주만의 서쪽인 노량수로와 동쪽인 대방수로에서 해수유동을 2005년부터 2008년까지 장기간 관측하였다. 진주만의 해수유동은 주로 노량수로와 대방수로를 통한 해수교환에 의해 지배된다. 동계 노량수로의 표층에서 조류는 광양만에서 동쪽인 진주만으로 유입하는 흐름이 발생하고, 저층에서는 진주만에서 서쪽인 광양만으로 유출하는 흐름이 발생하고 있다. 하계 노량수로의 표층에서 조류는 진주만에서 서쪽인 광양만으로 유출하는 흐름이 발생하고 있다. 즉, 노량수로에서 해수순환은 전형적인 열염분순환 형태를 보여주고 있다. 춘계 동-대방수로의 표층에서 조류는 진주만에서 외해로 유출하는 중력순환류가 발생하고 있다. 그러나, 하계 서-대방수로에서는 전층에 걸쳐 진주만내로 유입하는 흐름 양상을 보여주고 있다. 유속의 크기는 서-대방수로에서 유속이 동-대방수로에서 유속보다 약 50~70 cm/sec 정도 크게 나타났다. 노량수로와 대방수로에서 계절별 해수순환 패턴을 보다 정확하게 해석하기 위해서는 현장관측과 3차원 수치모형실험에 관한 상세한 연구가 추가적으로 수행되어야 할 것으로 사료된다. A seasonal circulation patterns in the Chinju Bay (CB) were suggested from the observed data at two channels of the Noryang Channel (NC) and the Daebang Channel (DC) during the period from 2005 to 2008. The water circulation in the CB is mainly controlled through the NC and the DC. In winter, tidal current at the surface layer of the NC flows from the Kwangyang Bay (KB) eastward into the CB, whereas the current at the bottom layer flows from the CB westward into the KB. In summer, tidal current at the surface layer of the NC goes from the CB westward into the KB. The flow system at the NC shows the typical pattern of thermohaline circulation. In spring, tidal current at the surface layer of the eastern part of the DC flows out into southeastern open ocean. However, in summer, the current in the western part of the DC flows into the CB through the DC. Also, the velocity in the western part of DC is 50~70 cm/sec stronger than that in the eastern part. To obtain better understanding on the seasonal circulation pattern in the NC and the DC, additionally the detailed studies on the field measurements and three dimensional numerical modeling are needed.

모형시험을 이용한 쌍동형 전기추진어선 선형개발에 관한 연구

정우철,박노식 한국기계기술학회 2011 한국기계기술학회지 Vol.13 No.4

Hull forms for catamaran type small fishing boat powered by electric motor are newly developed by experimental approaches. Model tests for two hull forms having different length are made at circulating water channel. Resistance performance and wave patterns are compared to carry out an analysis of the effect of extension of main body. The results show that the extension of main body can give better resistance performance above a certain velocity.

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

윤현규,강주년 한국항해항만학회 2010 한국항해항만학회지 Vol.34 No.7

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

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

Hyeon-Kyu Yoon,Joo-Nyun Kang 한국항해항만학회 2010 한국항해항만학회지 Vol.34 No.7

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.

Physical Experiments to Investigate the Effects of Street Bottom Heating and Inflow Turbulence on Urban Street-Canyon Flow

Jae-Jin, KIM,Jong-Jin, BAIK China Ocean Press ; Springer-Verlag 2005 Advances in atmospheric sciences Vol.22 No.2

<P>The effects of street bottom heating and inflow turbulence on urban street-canyon flow are experimentally investigated using a circulating water channel. Three experiments are carried out for a street canyon with a street aspect ratio of 1. Results from each experiment with bottom heating or inflow turbulence are compared with those without bottom heating and appreciable inflow turbulence. It is demonstrated that street bottom heating or inflow turbulence increases the intensity of the canyon vortex. A possible explanation on how street bottom heating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamical viewpoint.</P>

다양한 조류 환경 및 경계 조건에 따른 모노파일형 해상구조물의 동특성 변화 분석

정병진(Byung-Jin Jung),박종웅(Jong-Woong Park),이진학(Jin-Hak Yi),박진순(Jin-Soon Park) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.4

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.