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스테레오 PIV 기법에 의한 임펠러 와류유동의 3차원 구조측정
윤상열,김경천,Yoon, Sang-Youl,Kim, Kyung-Chun 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.6
The three-dimensional spatial structures of impeller flow created by a six bladed Rushton turbine have identified based on the volumetric velocity information from multi-plane stereoscopic PIV measurements. A total of 10 planes with 2 mm space and a 50 mm by 64 mm size of the field of view were targeted. To reduce the depth of focus, we adopted an angle offset configuration which satisfied the Scheimpflug condition. The distortion compensation procedure was utilized during the in situ calibration. Phase-locked instantaneous data were ensemble averaged and interpolated in order to obtain mean 3-D. volumetric velocity fields on a 60 degree sector of a cylindrical ring volume enclosing the turbine blade. Using the equi-vorticity surface rendering, the spatial structure of the trailing vortices was clearly demonstrated. Detail flow characteristics of the radial jet reported in previous studies of mixer flows were easily identified.
마이크로 레이저 평면빔을 이용한 마이크로채널 내에서의 Micro-LIF 측정
윤상열(Sang Youl Yoon),김재민(Jae Min Kim),김수헌(Su Hun Kim),김경천(Kyung Chun Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Measurement of concentration fields in a micro-channel is the crucial technology in the area of Lab-on-achip to be used for various bio-chemical applications. It is wel-known that the only possible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been made so far due to the limit of light illumination. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having 5 microns thickness by a micro focus laser line generator. Nile Blue A was used as fluorescent dye for LIF measurement. The laser sheet beam illuminates an exact plane of concentration measurement in the micro-channel to increase the signal to noise ratio and reduce the depth uncertainty considerably.
미세유체소자 내부에서의 Droplet 형성에 대한 Micro-PIV 측정
윤상열(Sang Youl Yoon),고춘식(Choon Sik Ko),김재민(Jae Min Kim),김경천(Kyung Chun Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This experiment has been carried out to measure the process of droplet formation between water phase fluid(PVA 3%) and organic phase fluid(oil) and vector fields measured by a Dynamic Micro-PIV method in the inside of a droplet while generated. Droplet length controlled by changing flow rate conditions in microchannel. Water-in-oil(W/O) droplets successfully generated at a Y junction and cross microchannel. But oil-in-water(O/W) droplets could not be formed at a Y junction microchannel. That is, PVA 3% flow could not be detached from the PDMS surface and ran parallel with oil flow. When PVA 3% flow rate was constant, droplet length and time period decreased as oil flow rate increased, but droplet frequency increased. When PVA 3% and oil flow rate ratio was constant, droplet length and time period decreased as flow rate increased, but droplet frequency increased. All that case, Standard deviation of droplet formation have less than 5% at averaged droplet length and regular-sized droplets were reproducibly formed.
다중평면 스테레오 PIV 기법에 의한 임펠러 와류유동의 3차원 난류 구조측정
윤상열(Sang Youl Yoon),김경천(Kyung Chun Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The three-dimensional spatial structures of impeller flow created by a six bladed Rushton turbine have identified based on the volumetric velocity information from multi-plane stereoscopic PIV<br/> measurements. A total of 10 planes with 2 mm space with a 50 mm by 64 mm size of the field of<br/> view were targeted. To reduce the depth of focus, we adopted an angle offset configuration which satisfied the Scheimpflug condition. The distortion compensation procedure was utilized during the in situ calibration. Phase-locked instantaneous data were ensemble averaged and interpolated in order to obtain mean 3-D, volumetric velocity fields on a 60 degree sector of a cylindrical ring volume enclosing the turbine blade. Three-dimensional structures of second-order turbulence statistics were examined by the conventional Reynolds decomposition method using instantaneous PIV data sets.
다양한 유체굴절률에서의 μ-DDPIV 적용을 위한 calibration보정기법
윤상열(Sang Youl Yoon),김경천(Kyung Chun Kim),Kenneth D. Kihm 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
This study presents a calibration compensation method for various refractive indices of working fluids in using micro defocusing digital particle image velocimetry (μ-DDPIV). The μ-DDPIV has been considered as one of advanced techniques for 3D particle tracking in a microvolume and 3D microflow diagnostics. In using the μ-DDPIV, the fluid refractive index is one of the important parameters by which the defocusing imaging is affected seriously. Therefore, the calibration coefficient compensation method should be beneficial. This paper describes the effects of the fluid refractive index (RI) on the z-calibration, and correlations between fluidrefractive index and calibration coefficient, (dz/dD).
마이크로유체소자 내부의 3 차원 입자추적 및 3 차원 유동장 측정기법 개발
윤상열(Sang Youl Yoon),김경천(Kyung Chun Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
This paper reports a detection method of 3D particle-positions and a 3D microflow diagnostic method in a microfluidic device or a microvolume. The main idea of this method is to use the defocusing concept by using three apertures and the apertures can allow one to get an image with 3D information of particles. This paper describes a simple system setup and an easy way to get 3D particle locations by using the defocusing concept. Just a plate with three apertures was placed on an objective lens. In this study, calibration-based defocusing method has been developed in stead of formulas which was introduced by geometrical analysis in previous studies. Particle trajectory with time and three dimensional velocity vectors were calculated in a micro backward facing step.
광파장 및 유체굴절률이 μ-DDPIV를 이용한 미세유동 3차원 측정에 미치는 영향
윤상열(Sang Youl Yoon),Kenneth D. Kihm,김경천(Kyung Chun Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
This study presents the effects of light wavelength and fluid refractive index on micro defocusing digital particle image velocimetry (μ-DDPIV). The μ-DDPIV has been considered as one of advanced techniques for 3D particle tracking in a microvolume and 3D microflow diagnostics. In using the μ-DDPIV, the light wavelength and fluid refractive index are one of the important parameters by which the defocusing imaging is affected seriously. This paper describes the effects of the fluid refractive index (RI) on the z-calibration, and a correlation between fluid refractive index and calibration coefficient, (dz/dD). In addition, the effects of light wavelength on image separation is demonstrated using optical bandpass filters with the central wavelengths of 480 ㎚, 540 ㎚, and 589㎚.
Experimental Study of 3D Flow in Chaotic Micromixers
Sang Youl Yoon(윤상열),Su Heon Kim(김수헌),Kyung Chun Kim(김경천) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This paper reports 3D flow and mixing patterns in chaotic micro-mixers measured by using a defocusing micro-PIV method. The tested mixers were a diagonal mixer and a staggered herringbone mixer, which are well known as chaotic micro-mixers. Chaotic micro-mixer has been designed with 3D shape to generate 3D flow behaviors for higher mixing efficiency. However, the previous studies were limited in a numerical simulation and a qualitative visualization due to complicated flow behaviors. In this study, the defocusing micro-PIV method has been applied to obtain exact 3D3C velocity fields measurements. Both large-scale turnover motions and small-scale meandering motion of particles are clearly observed.