• Title, Summary, Keyword: PIV

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Performance Test of 2-Dimensional PIV and 3-Dimensional PIV using Standard Images (표준화상을 이용한 2차원 PIV와 3차원 PIV계측 및 성능비교검정)

  • Doh, D.H.;Hwang, T.G.;Song, J.S.;Baek, T.S.;Pyun, Y.B.
    • Proceedings of the KSME Conference
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    • pp.646-651
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    • 2003
  • Quantitative performance test on the conventional 2D-PIV and the hybrid angular 3D-PIV (Stereoscopic PIV) was carried out. LES Data sets on an impinging jet which are provided on the webpage(http://www.vsj.or.jp/piv) for the PIV Standard Project were used for the generation of virtual images. The generated virtual images were used for the 2D-PIV and 3D-PIV measurements. The measurement results showed that the results obtained by 2D-PIV on average values are closer to the LES data than those obtained by 3D-PIV, but the turbulent properties obtained by 2D-PIV are largely underestimated than those obtained by 3D-PIV.

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Performance Test on 2-Dimensional PIV and 3-Dimensional PIV Using Standard Images (표준영상을 이용한 2차원 PIV와 3차원 PIV 성능시험)

  • Hwang, Tae-Gyu;Doh, Deog-Hee
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.11
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    • pp.1315-1321
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    • 2004
  • Quantitative performance test on the conventional 2D-PIV and the hybrid angular 3D-PIV(Stereoscopic PIV) was carried out. LES Data sets on an impinging jet which are provided on the webpage(http://www.vsj.or.jp/piv) for the PIV Standard Project were used for the generation of virtual images. The generated virtual images were used for the 2D-PIV and 3D-PIV measurements test. It has been shown that the results obtained by 2D-PIV on average values are slightly closer to the LES data than those obtained by 3D-PIV, but the turbulent properties obtained by 2D-PIV are largely underestimated than those obtained by 3D-PIV.

A Study on Measurement of Premixed Spray Flame using Cross-correlation PIV (상호상관 PIV를 이용한 예혼합 분무화염의 계측에 관한 연구)

  • Yang Young-Joon;Kim Bong-Hwan
    • Journal of Energy Engineering
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    • v.14 no.4
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    • pp.259-267
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    • 2005
  • In an attempt to elucidate combustion mechanism or premixed spray flame in detail, both the enlarged photographing, which was performed for spray cross-sectional images of premixed spray flame, and the cross-correlation PIV, which was performed for consecutive time-series images to obtain instantaneous two dimensional flow field, were applied. This study indicated that CW laser as well as pulse laser could be applied for PIV. Furthermore, the results of cross-correlation PIV, which was self-made PIV program, was shown in good agreement with those of PDA. Therefore, it was verified that cross-correlation PIV using CW laser in this study could be effectively used for observing structure of premixed spray flame.

Non-Invasive Measurement of Shear Rates of Pulsating Pipe Flow Using Echo PIV (에코 PIV를 이용한 맥동 유동에서의 in vitro 전단률 측정 연구)

  • Kim, Hyoung-Bum;Chung, In-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.12
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    • pp.1567-1572
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    • 2004
  • Although accurate measurement of velocity profiles, multiple velocity vectors, and shear stress in arteries is important, there is still no easy method to obtain such information in vivo. This study shows the utility of combining ultrasound contrast imaging with particle image velocimetry (PIV) for non-invasive measurement of velocity vectors. The steady flow analytical solution and optical PIV measurements (for pulsatile flow) were used for comparison. When compared to the analytical solution, both echo PIV and optical PIV resolved the steady velocity profile well. Error in shear rate as measured by echo PIV (8%) was comparable to the error of optical PIV (6.5%). In pulsatile flow, echo PIV velocity profiles agreed well with optical PIV profiles. Echo PIV followed the general profile of pulsatile shear stress across the artery but underestimated wall shear at certain time points. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

Development of higher performance algorithm for dynamic PIV

  • NISHIO Shigeru
    • 한국가시화정보학회:학술대회논문집
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    • pp.25-32
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    • 2004
  • The new algorithm for higher performance of dynamic PIV has been proposed. Present study considered mathematical basis of PIV analysis for multiple-time-step images and it enables us to analyze the high time-resolution PIV, which is obtained by dynamic PIV system. Conventional single pair image PIV analysis gives us the velocity field data in each time step but it sometimes contains unnecessary information of target flow. Present technique utilize multi-time step correlation information, and it is analyzed.

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Development and Application of a Miniature Stereo-PIV System (Miniature Stereo-PIV 시스템의 개발과 응용)

  • Kim, K.C.;Chetelat, Olivier;Kim, S.H.
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.11
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    • pp.1637-1644
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    • 2003
  • Stereoscopic particle image velocimetry is a measurement technique to acquire three dimensional velocity field by two cameras. With a laser sheet illumination, the third velocity component can be deduced from out-of$.$plane velocity components using a stereoscopic matching method. Most industrial fluid flows are three dimensional turbulent flows, so it is necessary to use the stereoscopic PIV measurement method. However the existing stereoscopic PIV system seems hard to use since it is very expensive and complex. In this study we have developed a Miniature Stereo-PIV(MSPIV) system based on the concept of the Miniature PIV system which we have already developed. In this paper, we address the design and some primitive experimental results of the Miniature Stereo-PIV system. The Miniature Stereo-PIV system features relatively modest performances, but is considerably smaller, cheaper and easy to handle. The proposed Miniature Stereo-PIV system uses two one-chip-only CMOS cameras with digital output. Only two other chips are needed, one for a buffer memory and one for an interfacing logic that controls the system. Images are transferred to a personal computer (PC) via its standard parallel port. No extra hardware is required (in particular, no frame grabber board is needed).

Development of X-ray PIV Technique and its Application to Blood Flow (X-ray PIV 기법의 개발과 혈액 유동에의 적용연구)

  • Kim, Guk Bae;Lee, Sang Joon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.11
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    • pp.1182-1188
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    • 2005
  • An x-ray PIV (Particle Image Velocimetry) technique was developed to measure quantitative information on flows inside opaque conduits and on opaque-fluid flows. At first, the developed x-ray PIV technique was applied to flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, refraction-based edge enhancement mechanism was employed using detectable tracer particles. The optimal distance between with the sample and detector was experimentally determined. The resulting amassed velocity field data were in reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to blood flow in a microchannel. The flow pattern of blood was visualifed by enhancing the diffraction/interference -bas ed characteristic s of blood cells on synchrotron x-rays without any contrast agent or tracer particles. That is, the flow-pattern image of blood was achieved by optimizing the sample (blood) to detector distance and the sample thickness. Quantitative velocity field information was obtained by applying PIV algorithm to the enhanced x-ray flow images. The measured velocity field data show a typical flow structure of flow in a macro-scale channel.

Development of single optical axis scanning PIV method (단일 광경로 스캔PIV기법의 개발)

  • Kim Hyoung-Bum;Jeong In-Young;Lee Sang-Hyuk;Ryu Chung-Hwan;Jean Hertzberg
    • 한국가시화정보학회:학술대회논문집
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    • pp.6-10
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    • 2005
  • PIV(Particle image velocimetry) presents the flow velocity of whole flow fields in a fraction of a second. 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 which this configuration is hard to be fulfilled. In this study, we developed new PIV method which only uses single optical axis to grab the particle images. This new PIV method become possible by utilizing the scanning method similar to echo PIV technique. One particle image of 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.

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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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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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