• Title/Summary/Keyword: Stereo PIV

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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 and Application of High-resolution 3-D Volume PIV System by Cross-Correlation (해상도 3차원 상호상관 Volume PIV 시스템 개발 및 적용)

  • Kim Mi-Young;Choi Jang-Woon;Lee Hyun;Lee Young-Ho
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.507-510
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    • 2002
  • An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity Held of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. Flows size is $1500{\times}100{\times}180(mm)$, particle is Nylon12(1mm) and illuminator is Hollogen type lamp(100w). The stereo photogrammetry is adopted for the three dimensional geometrical mesurement of tracer particle. For the stereo-pair matching, the camera parameters should be decide in advance by a camera calibration. Camera parameter calculation equation is collinearity equation. In order to calculate the particle 3-D position based on the stereo photograrnrnetry, the eleven parameters of each camera should be obtained by the calibration of the camera. Epipolar line is used for stereo pair matching. The 3-D position of particle is calculated from the three camera parameters, centers of projection of the three cameras, and photographic coordinates of a particle, which is based on the collinear condition. To find velocity vector used 3-D position data of the first frame and the second frame. To extract error vector applied continuity equation. This study developed of various 3D-PIV animation technique.

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Development of High-resolution 3-D PIV Algorithm by Cross-correlation (고해상도 3차원 상호상관 PIV 알고리듬 개발)

  • Kim, Mi-Young;Choi, Jang-Woon;Lee, Hyun;Lee, Young-Ho
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.410-416
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    • 2001
  • An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity field of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. In this study, stereo photogrammetty was applied for the 3-D matching of tracer particles. Epipolar line was used to decect the stereo pair. 3-D CFD data was used to estimate algorithm. 3-D position data of the first frame and the second frame was used to find velocity vector. Continuity equation was applied to extract error vector. The algorithm result involved error vecotor of about 0.13 %. In Pentium III 450MHz processor, the calculation time of cross-correlation for 1500 particles needed about 1 minute.

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Three Dimensional Vortex Behavior of LEX Delta Wing by Dynamic Stereo PIV (Dynamic Stereo PIV에 의한 델타형 날개에서의 3차원 와류 유동에 관한 연구)

  • Lee Hyun;Kim Mi-Young;Choi Jang-Woon;Choi Min-Seon;Lee Young-Ho
    • 한국가시화정보학회:학술대회논문집
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    • 2003.11a
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    • pp.39-42
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    • 2003
  • Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras$(1280pixel\times1024pixel)$ were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

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A Study on the Unsteady Flow Characteristics of a Delta Wing by 3-D Stereo PIV (3-D Stereo PIV에 의한 비정상 델타윙 유동특성에 대한 연구)

  • Kim, Beom-Seok;Lee, Hyun;Kim, Jeong-Hwan;Lee, Young-Ho
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1672-1677
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    • 2004
  • Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modem air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras($1280pixel{\times}1024pixel$) were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

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Development of 3-D Stereo PIV by Homogeneous Coordinate System (호모지니어스 좌표계를 이용한 3차원 스테레오 PIV 알고리듬의 개발)

  • Kim, Mi-Young;Choi, Jang-Woon;Nam, Koo-Man;Lee, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.6
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    • pp.736-743
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    • 2003
  • A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of an illuminated slied section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of the oblique-angled image to the right-angled image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterior, and finally 3-D animation as the post processing. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

Development of 3-D Stereo PIV (3차원 스테레오 PIV 개발)

  • Kim Mi-Young;Choi Jang-Woon;Nam Koo-Man;Lee Young-Ho
    • 한국가시화정보학회:학술대회논문집
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    • 2002.11a
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    • pp.19-22
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    • 2002
  • A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of a section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of oblique-angled image to transformed image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system and finally 3-D animation as the post processing. In principle, as two frame images only are necessary for the single instantaneous analysis of a section field of 3-D flow, more effective vectors are obtainable contrary to the previous multi-frame vector algorithm. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

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Study on the Three Dimensional Flow Characteristics of the Propeller Wake Using PIV Techniques (PIV 기법을 이용한 프로펠러 후류의 3차원 유동 특성 연구)

  • Paik, Bu-Geun;Kim, Jin;Kim, Kyung-Youl;Kim, Ki-Sup
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.3 s.153
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    • pp.219-227
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    • 2007
  • A stereo-PIV (particle image velocimetry) technique is used to investigate the vortical structure of the wake behind a rotating propeller in the present study. A four bladed propeller is tested in a cavitaion tunnel without any wake screen. Hundreds of instantaneous velocity fields are phase-averaged to reveal the three dimensional spatial evolution of the flow behind the propeller. The results of conventional 2-D PIV are also compared with those of the stereo-PIV to understand the vortical structure of propeller wake deeply. The variations of radial and axial velocities in the 2-D PIV results seem to be affected by the out-of-plane motion. generating a little perspective error in the in-plane velocity components of the slipstream. The strong out-of-plane motion around the hub vortex also causes the perspective error to vary the axial velocity component a little at the near wake region. The out-of-plane velocity component had the maximum value of about 0.3U0 in the tip vortices and continued its magnitude in the wake region.

A Study on the Turbulent Characteristics of Rushton Turbine Mixer by Simultaneous Measurement of Velocity and Concentration field with Stereo-PIV/PLIF Technique (Stereo-PIV/LIF의 속도장과 농도장 동시측정 기법을 이용한 러쉬톤 교반기내 난류특성에 관한 연구)

  • Min, Young-Uk;Kim, Yun-Gi;Kim, Kyung-Chun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.3
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    • pp.365-370
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    • 2004
  • Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereo Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K${\times}$2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent flow around Rushton turbine were identified by the calculation of synchronized data of the velocity field and concentration field.

A Study on the Turbulent Characteristics of Rushton Turbine Mixer by Simultaneous Measurement of Velocity and Concentration Field with Stereo-PIV/PLIF Technique (Stereo-PIV/PLIF의 속도장과 농도장 동시측정 기법을 이용한 러쉬톤 교반기내 난류특성에 관한 연구)

  • Min, Young-Uk;Kim, Yun-Gi;Kim, Kyung-Chun
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.694-699
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    • 2003
  • Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereoscopic Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K ${\times}$ 2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent mixing around Rushton turbine were identified by the calculation of cross-correlation fields between the velocity and concentration field.

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