• Title/Summary/Keyword: PIV measurements

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Research on Turbulent Premixed Flame with Simultaneous PIV/OH PLIF measurements (PIV/OH PLIF 동시측정을 이용한 난류 예혼합 화염 연구)

  • Cho Yong-jin;Kim Ji-ho;Cho Tae-young;Yoon Young-bin
    • 한국가시화정보학회:학술대회논문집
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    • 2002.11a
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    • pp.97-99
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    • 2002
  • Turbulent premixed flames were a subject of many researches for a number of decades. Especially, Borghi suggested a manificent diagram classifying turbulent combustion reasions and Lipatnikov and Chomiak modified this diagram. But this diagram has difficulties tn defining a flame thickness and velocity and measuring integral length scales In addition, recently experimental techniques are being developed, so we can accurately use PIV diagnostics measuring 2D velocity field instead of LDV and make good use of PLIF techniques for obtaining the flame information. In this study, according to developing techniques, suggest a new diagram replacing the existing Borghi diagram. Simultaneous PIV/OH PLIF measurements are used, which measure a shear strain rate and a location of flames, respectively. The shear strain rate represents turbulence and the OH signal indicates the flame information, but there is no geometric Information which is very important to flame quenching. Hence, to consider the geometric information, calculate fractal dimensions of the OH images. So the diagram suggested in this research has three axes which consist of strain rate, OH signal, and fractal dimension and can classify turbulent premixed flames.

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Error Analysis of Flow Velocity Measured through Granular PIV Based on Interrogation Area, Frame Per Second, and Video Resolution (상관 영역과 초당 촬영 수와 해상도에 따른 Granular PIV에서의 유동 속도의 오차 분석)

  • Choi, Jongeun;Park, Junyoung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.7
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    • pp.58-65
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    • 2021
  • Research on general particle image velocimetry (PIV) has been conducted extensively, but studies on granular PIV are relatively insufficient. In addition, the parameters used for analyzing granular PIV need to be optimized. In this study, we analyzed the error of velocity measurements based on the interrogation area (64-192 pixel), frame per second (30-120 FPS), and video resolution [ultrahigh definition (UHD) and high definition (HD)] within the velocity range typically measured in hoppers. The estimated errors of the granular PIV were below 5%, which is generally acceptable. However, considering the data reliability, the flow velocity in the hopper could be measured with less than 5% error at 120 FPS or higher in the HD resolution and 30 FPS or higher in the UHD resolution.

PIV Measurement on Airflows in the Abnormal Nasal Cavity with the Adenoid Vegetation (아데노이드 비대증에 의한 비정상 비강 내 유동의 PIV해석)

  • Kim, Sung-Kyun;Son, Young-Rak
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.4
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    • pp.518-523
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    • 2003
  • Airflow in the nasal cavity of Korean adults is investigated experimentally by PIV measurement. Quantitative data for normal and abnormal nasal cavities with adenoid vegetation are obtained. The CBC PIV algorithm with window offset is used for PIV flow analysis. Average and RMS distributions are obtained for inspirational and expirational nasal airflows. Comparisons between western and Korean nasal airflows are appreciated. Due to the difference in geometry of the frontal part of nasal cavity, the flow near nares shows the difference. For the joint research on nasal deceases, PIV measurements of nasal airflow for nasal cavities with 50% and 70% adenoid vegetation are conducted for the first time. Comparisons in nasal airflows for both normal and abnormal cases are also appreciated.

Echo-PIV: in vivo Flow Measurement Technique (에코 PIV: in vivo 유동 측정기법)

  • kim Hyoung-Bum;Hertzberg Jean;Shandas Robin
    • Journal of the Korean Society of Visualization
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    • v.3 no.1
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    • pp.26-35
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    • 2005
  • The combination of ultrasound echo images with digital particle image velocimetry (DPIV) method has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window of offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow and pulsatile flow showed good agreement with both optical PIV measurements and the known analytic solution. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

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Development of angiographic PIV and performance evaluation (Angiographic PIV기법 개발 및 성능 평가)

  • Jung, Sung-Yong;Kim, Guk-Bae;Lim, Nam-Yun;Lee, Sang-Joon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.683-686
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    • 2008
  • To diagnose vascular diseases from the viewpoint of hemodynamics, detailed quantitative hemodynamic information of related blood flows with a high spatial resolution of tens micrometer and a high temporal resolution in the order of millisecond were required. For investigating the hemodynamic phenomena of vascular circulatory diseases, a new diagnosing technique combining a medical radiography and PIV method was newly developed. This technique consisted of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulse-type X-ray source, and a synchronizer. Through several preliminary tests, the feasibility of the angiographic PIV technique was verified. For in-vivo measurements to real blood flows, we developed tracer microcapsules which were optimized to this system by encapsulating a contrast material of iodine with a matrix material of PVA (polyvinylpyrrolidone). In near future, the angiographic PIV technique would be useful for diagnosing hemodynamic phenomena of vascular diseases and for their early detection.

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Development of Echo PIV Using Ultrasound Contrast Agent (초음파 조영제를 애용한 Echo PIV 기법의 개발)

  • Kim, Hyoung-Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.12
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    • pp.1528-1534
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    • 2004
  • The combination of ultrasound echo images with digital particle image velocimetry (DPIV) methods has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow result of echo PIV showed good agreement with both optical PIV measurements and the known analytic solution based on a volume flow measurement.

Quantitative Measurements of Complex Flow Field Around a Hydrofoil Using Particle Image Velocimetry (PIV를 이용한 수중익 주위 복잡유동장의 정량적 계측)

  • B.S. Hyun;K.S. Choi;D.H. Doh
    • Journal of the Society of Naval Architects of Korea
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    • v.37 no.3
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    • pp.37-44
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    • 2000
  • An experimental study has been carried out at circulating water channel to investigate the viscous flow around breaking waves generated by a submerged hydrofoil(NACA0012). Detailed flow measurements were made at several critical points including an incipient wave-breaking point and a fully-developed wave breaker. Particle Image Velocimetry(PIV) was employed to visualize the flow field very close to the breaker as well as at the near- and far-wake of the breaker. Generation, development and decay of the wave breaker have been investigated. It is found that PIV technique could be well applied to the complex flow field, including the vortical structures near the free surface as well as the wake of the hydrofoil.

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Analysis of Flow in a Microchannel Branch by Using Micro-PIV Method (마이크로 PIV를 이용한 마이크로 분지관에서의 유동해석)

  • Yoon, Sang-Youl;Kim, Kyung-Chun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.9
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    • pp.1015-1021
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    • 2004
  • Micro-resolution Particle Image Velocimetry(Micro-PIV) was used to measure the flow in a micro-branch(Micro-Bypass). In this paper, effects of particle lump at the tip of a Micro-branch and difficulties of Micro-PIV measurements for microfluidics with branch passage were described. Micro-bypass was composed of a straight channel(200(100)${\mu}$m width ${\times}$ 80${\mu}$m height) and two branches which has 100(50)${\mu}$m width ${\times}$ 80${\mu}$m height. One of branches was straight and the other was curved. Experiments were performed at three regions along streamwise direction(entrance, middle and exit of branch) and five planes along vertical direction (0, ${\pm}$10, ${\pm}$20 ${\mu}$m) for the range of Re=0.24, 1.2, 2.4. Numerical simulation was done to compare with the measurements and understand the effects of particle lump at the tip of branch. And another fluid(3% poly vinyl Alcohol aqueous solution) were adapted for this study, so there were no particle sticking. In this case, we could get velocity difference between straight and curved branches.

Comparison of Swirl Ratio Measured by Impulse Swirl Meter and Particle Image Velocimetry in a Steady Flow Bench of SI Engine (SI 엔진의 정상유동장치에서 충격식 스월미터와 입자영상유속계의 스월비 측정에 대한 비교 연구)

  • Lee, Sukjong;Ohm, In Yong;Sung, Jaeyong
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.4
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    • pp.437-442
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    • 2015
  • The swirl ratio in a SI engine is investigated in a steady flow bench according to the measurement methods: an impulse swirl meter and particle image velocimetry (PIV). When measuring the swirl ratio using the PIV, the torque is evaluated based on the cylinder center and swirl center, respectively. The position of the measurement plane is considered. As a result, in the upstream, the swirl ratio measured by the impulse swirl meter is estimated to be larger than that from the PIV measurements due to the unstable vortex motions. Regarding the PIV measurements, the swirl ratio based on the cylinder center has been found to be lower than that based on the swirl center. On the other hand, the difference in swirl ratio has decreased smaller as the measurement plane moved downstream due to the stabilization of the vortex motion.

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 s.242
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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.