• Title, Summary, Keyword: PIV

Search Result 1,275, Processing Time 0.049 seconds

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
    • /
    • v.28 no.12
    • /
    • pp.1528-1534
    • /
    • 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.

Flow Survey around Two-Dimensional Circular Cylinder using PIV Technique (PIV를 사용한 2차원 원형 실린더 주위의 유동해석)

  • 박건선;곽영기
    • Journal of Ocean Engineering and Technology
    • /
    • v.18 no.3
    • /
    • pp.1-7
    • /
    • 2004
  • Flaw visualization and velocity field measurement methods have practical applications in the various fluid engineering fields, such as mechanics, ships, and heat fluids. In this study, the basic principles and theoretical methods are used to establish an application technique of Particle Imae Velocimetry(abbreviated to PIV below). Accordingly, the measured results of velocity field distribution of a section inside the Circulating Water Channel (abbreviated to CWC below) are computed using the PIV is presented. The uniformity of velocity distribution of the section in CWC is confirmed, by comparing this PIV data with the existing current meter data. Also, in order to measure the flaw fields of surroundings of 2-dimensional cylinder in the CWC, the flaw visualization technique using the PIV is applied.

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
    • /
    • v.17 no.12
    • /
    • pp.1154-1160
    • /
    • 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.

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
    • /
    • v.3 no.1
    • /
    • pp.26-35
    • /
    • 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.

  • PDF

Development of a Dynamic PIV System for Turbulent Flow Analysis (난류유동 해석을 위한 Dynamic PIV 시스템의 개발)

  • Lee Sang-Joon;Jang Young-Gil;Kim Seok
    • Journal of the Korean Society of Visualization
    • /
    • v.3 no.1
    • /
    • pp.71-77
    • /
    • 2005
  • Information on temporal evolution of whole velocity fields are essential for physical understanding of a complicated turbulent flow. Due to advances of high-speed imaging technique, laser and electronics, high-speed digital cameras and high-repetition pulse lasers are commercially available in nowadays. A dynamic PIV system that can measure consecutive instantaneous velocity field with 1K$\times$ 1K pixels resolution at 1 fps was developed. It consists of a high-speed CMOS camera and a high-repetition Nd:YLF pulse laser. Theoretically, it can capture velocity fields at 20 fps with a reduced spatial resolution. In order to validate its performance, the dynamic PIV system was applied to a turbulent jet of which Reynolds number is about 3000. The particle images of 1024$\times$512 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.

  • PDF

Advanced Flow Visualization Techniques for Diagnosing Microscale Biofluid Flows (미세 생체유동 해석을 위한 첨단 유동가시화기법)

  • Lee, Sang-Joon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.1
    • /
    • pp.1-8
    • /
    • 2009
  • Recently microscale biofluid flows have been receiving large attention in various research areas. However, most conventional imaging techniques are unsatisfactory due to difficulties encountered in the visualization of microscale biological flows. Recent advances in optics and digital image processing techniques have made it possible to develop several advanced micro-PIV/PTV techniques. They can be used to get quantitative velocity field information of various biofluid flows from visualized images of tracer particles. In this paper, as new advanced micro-PIV techniques suitable for biofluid flow analysis, the basic principle and typical applications of the time-resolved micro-PIV and X-ray micro-PIV methods are explained. As a 3D velocity field measurement technique for measuring microscale flows, holographic micro-PTV method is introduced. These advanced PIV/PTV techniques can be used to reveal the basic physics of various microscale biological flows and will play an important role in visualizing veiled biofluid flow phenomena, for which conventional methods have many difficulties to analyze.

Development of Stereoscopic PIV Measurement Technique and Its Application to Wake behind an Axial Fan (Stereoscopic PIV 기법의 개발과 이를 이용한 축류 홴 후류의 유동해석)

  • Yun, Jeong-Hwan;Lee, Sang-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.2
    • /
    • pp.362-373
    • /
    • 2002
  • A stereoscopic PIV (SPIV) measurement system based on the translation configuration was developed and applied to the flow behind a forward-swept axial-fan. Measurement of three orthogonal velocity components is essential for flow analysis of three-dimensional flows such as flow around a fan or propeller. In this study, the translation configuration was adopted to calculate the out-of-plane velocity component from 2-D PIV data obtained from two CCD cameras. The error caused by the out-of-plane motion was estimated by direct comparison of the 2-D PIV and 3-D SPIV results that measured from the particle images captured simultaneously. The comparison shows that the error ratio is relatively high in the region of higher out-of-plane motion near the axial fan blade. The turbulence intensity measured by the 2-D PIV method is bigger by about 5.8% in maximum compared with that of the 3-D SPIV method. The phase-averaged velocity field results show that the wake behind an axial fan has a periodic flow structure with respect to the blade phase and the characteristic flow structure is shifted downstream in the next phase.

Development of a Stereoscopic Miniature PIV(MPIV) System (Stereoscopic Miniature PIV (MPIV) 시스템의 개발)

  • Kim S.H.;Chete1at O.;Kim K.C.
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.517-520
    • /
    • 2002
  • Stereoscopic particle image velocimetry is a measurement technique to acquire of three dimensional velocity field by two cameras. With a laser sheet illumination, the third velocity component can be deduced by out-of-plane velocity components using a stereoscopic matching method. Industrial fluid flows are almost 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 Stereoscopic Miniature PIV(MPIV) system based on the concept of the Miniature PIV system which we have already developed. In this paper, we address the design and some first experimental results of the stereoscopic PIV system. The Stereoscopic MPIV system features relatively modest performances, but is considerably smaller, cheaper and easy to handle. The proposed Stereoscopic MPIV 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).

  • PDF

Spatial Analysis of Turbulent Flow in Combustion Chamber using High Resolution Dual Color PIV (고분해능 이색 PIV를 이용한 가솔린 엔진 연소실내 난류의 공간적 해석)

  • Lee, K.H.;Lee, C.S.;Lee, H.G.;Chon, M.S.;Joo, Y.C.
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.6
    • /
    • pp.132-141
    • /
    • 1998
  • Particle image velocimetry(PIV), a planar measuring technique, is an efficient tool for studying the complicated flow field such as in-cylinder flow, and intake port flow. PIV can be also used for analyzing the integral length scale of turbulence, which is a measure of the size of the large eddies that contain most of the turbulence kinetic energy. In this study, dual color scanning PIV was designed and demonstrated by using a rotating mirror and a beam splitter. This PIV system allowed enlargement of flexibility in the intensity of vectors to be calculated by spatial filtering technique, even in combustion chamber with high velocity gradient and high vorticity$({\sim}1000s^{-1})$. A new color image processing algorithm was developed, which was used to find the direction of particle movement directly from the digital image. These measuring techniques were successfully applied to obtaining the turbulence intensity (~0.1m/s) and the turbulent integral length scale of vorticity(~1mm).

  • PDF

PIV Applications for Flow Analysis of Tetrapod and Artificial Reef (소파블록과 인공어초 주위의 유동 해석을 위한 PIV 적용)

  • Lee Gyoung-Woo;Jo Dae-Hwan;Kim Ho;Lee Seung-Keon
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • /
    • pp.141-146
    • /
    • 2005
  • This paper an application example of PIV system for analyzing the flow of submerged structure. In this paper, we introduce an analysis method to predict the characteristics of flow around the neighboring fields of tetrapod and fishing reef in order to develop a high performance model. Flowing phenomenon according to velocity distribution and flow separation around the submersed body were obtained by PIV system. Flow visualization has conducted in a circulating water channel by a high speed camera and etc.

  • PDF