• Title, Summary, Keyword: PIV

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Stereoscopic PIV (스테레오 PIV)

  • Doh, D.H.;Lee, W.J.;Cho, G.R.;Pyun, Y.B.;Kim, D.H.
    • Proceedings of the KSME Conference
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    • pp.394-399
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    • 2001
  • A new stereoscopic PIV is introduced. The system works with CCD cameras, stereoscopic photogrammetry, and a 3D-PTV principle. Virtual images are produced for the construction of a benchmark testing tool of PIV techniques. The arrangement of the two cameras is based on angular position. The calibration of cameras and the pair-matching of the three-dimensional velocity vectors are based on 3D-PTV technique.

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Development of X-ray PIV System Using a Medical X-ray Tube (임상용 X-선관을 이용한 X-ray PIV시스템의 개발)

  • Yim, Dae-Hyun;Kim, Guk-Bae;Kim, Do-Il;Lee, Hyong-Koo;Lee, Sang-Joon
    • 유체기계공업학회:학술대회논문집
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    • pp.403-406
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    • 2006
  • A new medical X-ray PIV technique was developed using a conventional medical X-ray tube. To acquire images of micro-scale particles, the X-ray PIV system consists of an x-ray CCD camera with high spatial resolution, and a X-ray tube with small a focal spot. A new X-ray exposure control device was developed using a rotating disc shutter to make double pulses which are essential for PIV application. Synchronization methodology was also developed to apply the PIV technique to a conventional medical X-ray tube. In order to check the performance and usefulness of the developed X-ray PIV technique, it was applied to a glycerin flow in an opaque silicon tube. Tungsten particles which have high X-ray absorption coefficient were used as tracer particles. Through this preliminary test, the spatial resolution was found to be higher than ultrafast MRI techniques, and the temporal resolution was higher than conventional X-ray PIV techniques. By improving its performance further and developing more suitable tracers, this medical X-ray PIV technique will have strong potential in the fields of medical imaging or nondestructive inspection as well as diagnosis of practical thermo-fluid flows.

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Application of PIV in the Flow Field Over a Fixed Dune Bed (언덕이 있는 하상유동 계측을 통한 PIV기법의 수력학적 적용연구)

  • Hyun B. S.;Balacharldar R.;Patel V, C.
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.5 no.3
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    • pp.10-15
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    • 2002
  • The assessment of PIV to measure the mean velocity and turbulence was carried out over a train of fixed two-dimensional dunes. The agreement between the PIV and LDV is good enough even in regions of flow reversals and high shear. Though limited in the wall normal direction field-of-view, PIV provides instantaneous flow fields, which reveal the complex nature of flow over dunes, as well as more sophisticated analyses such as two-point space correlation and quadrant analysis with a reasonable accuracy The present study is expected to be directly applied to more complex flow such as sediment transport.

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Flow Characteristics for PIV Visualization at Junction Duct (PIV 가시화에 의한 합류덕트에서의 유동특성)

  • Kim, M.K.;Kwon, O.B.;Bae, D.S.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.45-50
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    • 2005
  • Characteristics of flows at T-junction duct with and without orifices are investigated in this paper. Experiments and PIV visualization were carried out for several flow rates. Two-dimensional PIV experimental apparatus was decided by numerical analysis. PIV visualization was also coded to visualize flow fields at junctions for two-dimensional case. For the PIV visualization system, Grey-Level Cross-Correlation particle tracking algorithm was used to calculate the flow fields. Vinyl chloride polymer particles of $100{\sim}150{\mu}m$ of diameter are used in this visualization. The PIV visualization results showed relatively good agreement with Experimental data.

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Development of Standard Experimental Apparatus for PIV Performance Evaluation (PIV 성능시험을 위한 표준실험장치 개발)

  • Sung, Jae-Yong;Doh, Deog-Hee;Lee, Suk-Jong;Hwang, Tae-Gyu
    • Journal of the Korean Society of Visualization
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    • v.4 no.2
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    • pp.37-43
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    • 2006
  • An experimental apparatus for PIV performance evaluation has been developed. Stardard uncertainty of a two-dimensional cross-correlation PIV system was investigated based upon the standard experimental apparatus, which was devised to model the rigid body rotating flows. For the systematic analysis of the uncertainty introduced by each component (algorithm, CCD camera, frame grabber) of the PIV system, standard images are fed into the component independently. The standard experiments show that 53% of the uncertainty in the present PIV system results from the frame grabber but the errors from the algorithm and digital camera are ignorable.

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Measurement of turbulent jet flow using dynamic PIV technique (Dynamic PIV를 이용한 난류 제트유동 해석)

  • Lee Sang-Joon;Jang Young-Gil;Kim Seok
    • 한국가시화정보학회:학술대회논문집
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    • pp.36-39
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    • 2005
  • Information on temporal evolution of whole velocity fields is essential for physical understanding of a complicated turbulent flow and was obtainable using dynamic PIV because of advances of high-speed imaging technique, laser and electronics. A dynamic PIV systme consists of a high-speed CMOS camera having $1K\times1K$ pixels resolution at 1 KHz and a high-repetition Nd:Yag pulse laser. In order to validate its performance, the dynamic PIV system was applied to a turbulent jet whose Reynolds number is about 3000. The particle images of $1024\times512$ pixels were captured at a sampling rate of 4 KHz. The dynamic PIV system measured successfully the temporal evolution of instantaneous velocity fields of the turbulent jet, from which spectral analysis of turbulent structure was also feasible.

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Development of the Scanning PIV Method with Single Optical Axis (단일 광경로 스캐닝 PIV기법 개발)

  • Kim, Hyoung-Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.2
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    • pp.181-187
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    • 2007
  • Conventional PIV method uses two optical axis configuration during the image grabbing process. That is, the illumination plane and the recording plane must be parallel. This configuration is very natural to grab the whole field without the image distortion. In the real problem, it is often to meet the situation when this configuration is hard to be fulfilled. In the present study, the new PIV method which uses only single optical axis to grab the particle images is developed. This new PIV method becomes possible by utilizing the scanning method similar to the echo PIV technique. One particle image of the scanning PIV consists of scanned several line images and by repeating this scanning process, two particle images were grabbed and processed to produce the velocity vectors. An optimization study was performed to find parameters which minimize the measurement errors. The effects of particle diameter, beam overlap ratio and particle number density were investigated.

Flow Visualization in the Branching Duct by Using Particle Imaging Velocimetry (입자영상유속계를 이용한 분기관내 유동가시화)

  • No, Hyeong-Un;Seo, Sang-Ho;Yu, Sang-Sin
    • Journal of Biomedical Engineering Research
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    • v.20 no.1
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    • pp.29-36
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    • 1999
  • The objective of this study is to analyse the flow field in the branching duct by visualizing the flow phenomena using the PIV system. A bifurcation model is fabricated with transparent acrylic resin to visualize the whole flow field with the PIV system. Water was used as the working fluid and the conifer powder as the tracer particles. The single-frame and two-frame methods of the PIV system and 2-frame of the grey level correlation method are applied to obtain the velocity vectors from the images captured in the flow filed. The velocity distributions in a lid-driven cavity flow are compared with the so-called standard experimental data, which was obtained from by 4-frame method in order to validate experimental results of the PIV measurements. The flow patterns of a Newtonian fluid in a branching duct were successfully visualized by using the PIV system and the sub-pixel and the area interpolation method were used to obtain the final velocity vectors. The velocity vectors obtained from the PIV system are in good agreement with the numerical results of the 3-dimensional branch flow. The results of numerical analyses and the PIV experiments for the three-dimensional flows in the branch ing duct show the recirculation zone distal to the branching point and the sizes of the recirculation length and height of the tow different methods are in good agreement.

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Analysis of Airflows in a Room with Panoramic PIV (파노라마-PIV를 이용한 실내기류 해석)

  • Hwang Tae-Gyu;Doh Deog-Hee
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.12
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    • pp.1154-1160
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    • 2005
  • A panoramic-PIV system has been constructed for the analysis of the airflows in a room. Smoke is used as seeding particles and are visualized by a pulsed laser (Nd-Yag, 120 mJ). Panoramic images have been obtained by an image composition process using the two images obtained by the two cameras $(1k\times1k)$ that are viewing the wide measurement areas. Velocity vector fields have been obtained by the grey-level cross-correlation PIV method. Three room models $(L{\times}W{\times}H[mm^3],\;500\times500\times250,\;350\times350\times175,\;250\times250\times125)$ have been tested. The experimental results have proven that the constructed panoramic-PIV system can be used as a useful tool for analyzing the airflow characteristics in the room models.