• 한국해양공학회지
• /
• 제10권3호
• /
• pp.89-95
• /
• 1996

The flow field around four cylinders for various angles was investigated utilizing particle image velocimetry(PIV) technique. Flow field was recorded by video camera first. Then application of PIV technique was done to the flow field. The results turned out to be useful to analyze complex flow field around multiple cylinders.

• 대한기계학회논문집B
• /
• 제24권4호
• /
• pp.504-511
• /
• 2000

PIV(Particle Image Velocimetry) is a recently developed technique for visualizing the fluid velocity fields. Because it has several advantages over the LDV(Laser Doppler Velocimetry), it became one of the most popular diagnostic tools in spite of its short history. However, its application to combustion is restricted by some problems such as flame illumination, scattered light refraction, particle density variation due to heat release, the combined effect of abrupt change in particle density and fluid velocity on flame contour, and thermophoresis which is particle lagging due to temperature gradient. These problems are expected to be originated from the non-continuous characteristics of flames and the limitations of particle dynamics. In the present study, these problems were considered for the visualization of the instantaneous coaxial hydrogen diffusion flame. And the instantaneous flame contour was detected using particle density difference. The visualized diffusion flame velocity field shows its turbulent and meandering nature. It was also observed that the flame is located inside the outer shear layer and flame geometry is largely influenced by the vorticity.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권4호
• /
• pp.898-903
• /
• 2001

The particle image velocimetry with liquid crystal tracers is used for visualizing and analysis of the bubbly flow in a vertical temperature gradient. This method allows simultaneous measurement of velocity and temperature field at a given instant of time Quantitative data of velocity were obtained by applying the MQD technique to visualized image. The paper describes the method, and presents the transient velocity patterns of bubbly flow.

• 대한기계학회논문집B
• /
• 제30권3호
• /
• pp.215-221
• /
• 2006

A stereoscopic particle tracking velocimetry (SPTV) technique based on the 2-frame hybrid particle tracking velocimetry (PTV) method was developed. The expansion of 2D PTV to SPTV is facilitated by the fact that the PTV method tracks individual particle centroids. To evaluate the performance and measurement accuracy of the present SPTV technique, it was applied to flow images of rigid body translation and synthetic standard images of jet shear flow and impinging jet flow. The data processing routine and measurement uncertainty of the SPTV technique are compared with those of conventional stereoscopic particle image velecimet.y (SPBV). In addition, the centroid translation effect of 2D particle image velocimetry (PIV) is defined and its effect on SPIV measurements is discussed. Compared to the SPIV method, the SPTV technique has inherited merits of concise and precise velocity evaluation procedures and provides better spatial resolution and measurement accuracy.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.312-315
• /
• 2008

The flow structure behind circular and elliptical type rings embedded in a cross-flow was investigated experimentally using two-frame particle image velocimetry (PIV). The experiments were performed in a circulating water channel with a test section of 0.35m height ${\times}$ 0.3m width ${\times}$ 1.1m length. PIV measurements were carried out with varying the Reynolds number in the range of 4.5 ${\times}$ $10^2$ - 4.5 ${\times}$ $10^3$. In the present study, turbulent flow structures in the stream-wise direction and span-wise direction were investigated. The mean velocity field distribution was obtained by statistical-averaging instantaneous velocity fields. The spatial distributions of turbulent statistics such as turbulent intensities and turbulent kinetic energy were also investigated.

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• pp.9-16
• /
• 2002

The particles velocity in the instantaneous flow field and velocity change of particles along the jet centerline for various particle diameter in a circular turbulent impingement jet are investigated by using particle image velocimetry(PIV) and an equation of particle motion simplified by terms of inertia forces, drag and gravitational force. The jet Reynolds number was 3300 and 8700, and glass beads of 30,58 and 100$\mu$m in diameter were used. The PIV results show that the direction and size of velocity depends not only on the number density of particle but also on the particle momentum. The results obtained form calculation suggest that the particle velocity near the first impingement region deviated from local air velocity, which accords well with the PIV results. The rebound height of particle increase with the particle diameter. In the second-impingement, particle velocities increased sluggishly with Re=3300 but particle velocities uniformed with Re=8700 in stagnation region.

• 대한기계학회논문집B
• /
• 제24권2호
• /
• pp.153-160
• /
• 2000

A Particle Image Velocimetry(PIV) algorithm is developed to analyze whole flow field both qualitatively and quantitatively. The practical use of PIV requires the use of fast, reliable, computer-based methods for tracking numerous particles suspended in a flow field. The TSS, NTSS, FFT-Hybrid, which are developed in the area of image compression and coding, are introduced to develop fast vector search algorithm. The numerical solution of the lid-driven cavity flow by the ADI algorithm with the Wachspress Formula is introduced to produce synthetic data for the validation of the tracking algorithms. The algorithms are applied to image data of real flow experiments. The comparisons in CPU time and mean error show, with a small loss of accuracy, CPU time for tracking is reduced considerably.

• 한국가시화정보학회지
• /
• 제21권1호
• /
• pp.119-126
• /
• 2023

Acquiring experimental data for PIV verification or machine learning training data is resource-demanding, leading to an increasing interest in synthetic particle images as simulation data. Conventional synthetic particle image generation algorithms do not follow physical laws, and the use of CFD is time-consuming and requires computing resources. In this study, we propose a new method for synthetic particle image generation, based on a Physics-Informed Neural Networks(PINN). The PINN is utilized to infer the flow fields, enabling the generation of synthetic particle images that follow physical laws with reduced computation time and have no constraints on spatial resolution compared to CFD. The proposed method is expected to contribute to the verification of PIV algorithms.

• 한국추진공학회지
• /
• 제16권6호
• /
• pp.9-15
• /
• 2012

추력변화를 초공동 수중운동체의 추진체로 사용되는 수반응성 금속입자와 해수는 연소챔버 내에서 균질하게 혼합될 때 비추력이 극대화 된다. 본 연구의 목적은 상사성의 관점에서 분사기 형상이 입자 분포에 미치는 영향을 알아보는 것이다. 이를 위해 PIV기법을 이용하여 반경방향의 입자 분포와 입자 평균속도의 상사성에 대하여 알아보았다.

• 대한기계학회논문집B
• /
• 제35권6호
• /
• pp.603-608
• /
• 2011

입자추적유속계(PTV)는 나노 및 바이오 분야의 유체유동장에서는 각 입자들을 추적하여 속도측정을 하는 관계로 많은 강점이 있다. 그러나 측정원리상 보간에 의한 속도장 측정오차를 피할 수 없는 관계로 PTV기술을 사용함에 있어서 제한적이었다. 본 연구에서는 어파인변환 알고리듬을 PIV 및 PTV측정에 도입함으로써 보간에 의한 오차를 줄일 수 있는 어파인변환 기반 하이브리드 PIV알고리듬을 구축하였다. 구축된 알고리듬에 대한 성능평가를 위하여 Green-Taylor와유동의 수치적 데이터를 이용한 가상영상에 대한 시험을 실시하였으며, 이로부터 입자수가 2000개 이상일 때 최적의 측정성능임을 확인하였으며 상호상관PIV법 및 확률일치PTV법보다 우수한 측정성능임을 확인하였다. 나아가 길이비 2:1($6cm\;{\times}3cm$)인 장방형 물체후류(Re=5,300)에 대한 실험영상에 대한 실제 계산을 통하여 구축된 알고리듬에 대한 측정성능의 우수성을 확인하였다.