• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.673-679
• /
• 2000

LNG Carriers are currently known as sole commercial means of shipping natural gas on the sea. They are designed to proven dangerous explosion for shipping a lot of gas over long distance. In this study. In this study, a scaled model chamber was made to investigate ventilation characteristics of the hood room in LNG carrier. Experimental study was performed in model using visualization equipments with laser apparatus and image intensifier CCD camera gated by an AOM controller Twelve different kinds of measuring area were selected as experimental condition. Instant simultaneous velocity vectors at whole field were measured by using 2-D PIV system which software adopts two-frame grey-level cross correlation algorithm. To look into stagnation area of hood room for LNG carrier, a three-dimensional numerical simulation with standard ${\kappa}-{\varepsilon}$ model was carried out by using PHOENICS for three kinds of Reynolds number, $6.5{\times}10^3$, $9.7{\times}10^3\;and\;1.29{\times}10^4$, based on the cavity inlet velocity and cavity height. The flow pattern showed the large scale counter-clockwise forced-vortex rotated at center area, small eddies at each corner and stagnation area located at left-back upper side of model.

• 한국해양공학회지
• /
• 제23권1호
• /
• pp.43-47
• /
• 2009

This paper compares theoretical wave profile and particle kinematics with experimental results generated by a 2 D wave tank. Particle velocity fields of compound waves were acquired using a PIV technique. Synchronization was applied to acquire images of the wave fields, and the time gap between these images was controlled by the user. This technique was applied to investigate the wave breaking mechanism, and the wave profile and velocity distribution in a wave breaking field was obtained.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
• /
• pp.375-376
• /
• 2006

Turbulent structure of a boundary-layer over a flat plate coated with micro riblet film(MRF) has been investigated experimentally. The turbulent structure was visualized using a dynamic particle image velocimetry (Dynamic PIV) system. We identified the vortex structures from 2-D velocity field data by applying the complex eigenvalue definition. The velocity field images acquired by using the complex eigenvalue definition showed the whole 2-D vortex structures clearly. In addition, the spatial distributions of small-scale vortices as well as large-scale vortices were obtained with high accuracy. The difference of vortex structures between the MRF coated flat plate and the smooth flat plate was analysed in detail. With varying upstream flow speed, the characteristics of vortex structure over the MRF coated flate plate was compared with those over the smooth flat plate.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2003년도 추계학술대회 논문집
• /
• pp.103-106
• /
• 2003

An experimental investigation was peformed to study the characteristics of ER(Electro-Rheological) fluid water flow in a horizontal rectangular tube with or without D.C volatage. To determine some characteristics of the ER flow, 2D PIV(Particle Image Velocimetry) technique is employed for velocity measurement. This research found the mean velocity distribution with 0 kV/mm, 1.0kV/mm and 1.5kV/mm for Re = 0, 0.62, 1.29 and 2.26. When the strength of the electric field increased, the claster of ERF are clearly strong along the test tube and the flow rate decreased.

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권1호
• /
• pp.116-123
• /
• 2004

An experimental investigation was performed to study the characteristics of ER (Electro-Rheological) fluid flow in a horizontal rectangular tube with or without D.C volatage. To determine some characteristics of the ER flow. 2D PIV(Particle Image Velocimetry) technique is employed for velocity measurement. This research found the mean velocity distribution with 0 kV/mm. 1.0kV/mm and 1 5kV/mm for Re=0, 0.62, 1.29 and 2.26. When the strength of the electric field increased. the claster of ERF are clearly strong along the test tube and the flow rate decreased.

• 대한의용생체공학회:의공학회지
• /
• 제15권4호
• /
• pp.489-497
• /
• 1994

The most serious problems related to the cardiovascular prothesis are thrombosis and hemolysis. It is known that the flow pattern of cardiovascular prostheses is highly correlated with thrombosis and hemolysis. Laser Doppler Anemometry (LDA) is a usual method to get flow pattern, which is difficult to operate and has narrow measure region. Particle Image Velocimetry (PIV) can solve these problems. Because the flow speed of valve is too high to catch particles by CCD camera, high-speed camera (Hyspeed : Holland-Photonics) was used. The estimated maximum flow speed was 5m/sec and maximum trackable length is 0.5 cm, so the shutter speed was determined as 1000 frames per sec. Several image processing techniques (blurring, segmentation, morphology, etc) were used for the preprocessing. Particle tracking algorithm and 2-D interpolation technique which were necessary in making gridrized velocity pronto, were applied to this PIV program. By using Single-Pulse Multi-Frame particle tracking algorithm, some problems of PIV can be solved. To eliminate particles which penetrate the sheeted plane and to determine the direction of particle paths are these solving methods. 1-D relaxation fomula is modified to interpolate 2-D field. Parachute artificial heart valve which was developed by Seoul National University and Bjork-Shiely valve was testified. For each valve, different flow pattern, velocity profile, wall shear stress and mean velocity were obtained.

• 한국해양공학회지
• /
• 제12권1호
• /
• pp.113-119
• /
• 1998

An experimental study was carried out in a three-dimensional cubic cavity driven by 2-dimensional plane Poiseuille flow for three kinds of Reynolds number, $10^4$, 3 $\times$ $10^4$ and 5 $\times$ $10^4$ based on the cavity width and cavity inlet mean flow velcoity. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system. Laser based illumination and two-frame grey-level cross correlation algorithm are adopted. Severe unsteady flow fluctuation within the cavity are remarkable at above Re = 3 $\times$ $10^4$ Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving Poiseuille flow is collided with the clock-wise rotating main primary vortex at upper center area. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the separate two areas.

• 한국항공우주학회지
• /
• 제30권1호
• /
• pp.95-104
• /
• 2002

램제트 연소기내의 복잡한 고속 유동의 가시화를 위해 two color PIV 기법을 개발하였다. Two color PIV 기법은 두 레이저 빔 사이의 시간 간격을 ㎲ 단위 이하로 조절할 수 있어 고속 유동에의 적용이 가능할 뿐 아니라, 기록된 필름에서의 색분리를 통하여 방향성의 분제를 해결할 수 있으며, 거의 완벽한 cross-correlation이 가능하여 signal-to-noise ratio가 상당히 증가한다는 장점을 갖게 된다. 본 연구에서는 램제트 엔진에 대한 기초 연구로서 양쪽 대칭의 공기 흡입구를 갖는 2차원 형태의 램제트 엔진 연소기를 제작하였고, two color PIV 기법을 이용하여 실험을 수행하였다. 흡입공기의 연소실내 유입각도와 연소시내 도움 위치에 따른 연소실 형상을 바꾸어가며 재순환 영역과 유입공기의 혼합과 같은 유동 특성을 분석하였다. 유입각도는 전체 유동장 뿐 아니라 재순환 영역의 크기와 재순환 영역내의 공기질량비에 상당한 영향을 끼치나, 도움 높이는 재순환 영역에 큰 영향을 주지 않는다는 것을 알 수 있었다.

• 한국항해항만학회지
• /
• 제32권6호
• /
• pp.453-458
• /
• 2008

원형실린더에 크기가 다른 제어봉을 부착하여 2차원 단면 유통특성에 대해서 시간평균유동장을 계측하여 근접후류 제어에 관하여 PIV기법을 적용하여 연구를 수행하였다. 모델시험은 각각 크기가 다른 제어봉을 적용하였으며($d/D=0.1{\sim}d/D=0.5$) 레이놀즈수는 원형실린더의 직경을 기준으로 Re=15,000으로 적용하였다. 유동장의 속도분포론 획득하기 위해 2프레임 상호상관법을 이용하였다. 실험에 적용된 원형실린더(D=50mm)에 제어봉을 부착한 결과를 상호 비교함으로서 시간평균속도분포와 제어봉에 의한 유동제어 효과를 알 수 있었다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.405-409
• /
• 2001

An experimental analysis of the flow inside the refrigeration compartment of a home refrigerator was conducted in order to achieve better performances in terms of uniform temperature distribution and cooling speed. 2D PIV and stereoscopic PIV were used for the experiments on an actual-size refrigerator at operating conditions. Two CCD cameras were employed for a wider field of view in the measurement of the shelf, and stereoscopic PIV was used to measure the three velocity components at the various cooling duct outlets and the mean velocity fields were area-integrated to calculate the flow-rates. 50 to 100 instantaneous velocity fields were time averaged for the mean velocity fields. With the result of this analysis, a new cooling duct system was developed, with the refrigerator's cooling performance increasing 11% in terms of cooling speed, and 25% in temperature uniformity.