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마이크로 채널 내 교류 인가에 의한 입자거동특성에 대한 연구
허형석(Hyeung Seok Heo),서용권(Yong Kweon Suh) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This paper shows particle deformation in the microchannel with rectangular electrode on the bottom wall for the AC-electroosmotic flows. We make the PDMS microchnnel with ITO electrodes. To see and measure the velocity distributions of the particles we used PTV technique. Particles with AC move to side wall or center of the channel for the special height. Also we induce a function of frequency at the electrode. We found that the velocity of particles is the most at the edge of the electrodes and direction angle of the ones also changes with the frequency
국소 제타포텐셜 조절이 마이크로 채널내 유체혼합에 미치는 영향
허형석(Hyeung Seok Heo),서용권(Yong Kweon Suh) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study a microchannel with series of electrodes is newly proposed as a mixing device. This design comprises periodically attached triangular electrode with a insulator. In this configuration, the stirring is shown to be greatly enhanced at a certain combination geometric set. To characterize the flow field and the stirring effect the numerical methods were employed. To obtain the velocity field, three-dimensional numerical computation are performed by using a commercial code, CFX 10. The fluid-flow solutions are then cast into studying the characteristics of stirring with the aid of Mixing index. The numerical results show that the particles' trajectories is significant enhanced at larger relative dimensionless velocity obtained from relative zeta potential between general wall and triangular electrode wall and it reaches maximum when the relative dimensionless velocity is -2.
정적연소기 부실내 잔류공기 소기특성에 대한 수치해석적 연구
허형석(Hyeung Seok Heo),서용권(Yong Kweon Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
In this paper, we present scavenge characteristics in a small subchamber of HCCI. It is very important to enhance scavenge rate because ignition in a chamber sometimes does not happen. To understand this phenomenon numerical tool was performed using the FLUENT which is a commercial code. Focus is given to the effect on the scavenge rate of the geometric factor that is the angle of nozzle injection. The numerical results show that the scavenge ones in the subchamber heavily depend on the nozzle angle. It was found that the scavenge rate is more effective at angled nozzle.
허형석(Hyeung Seok Heo),전종현(Jong Hyun Jeong),서용권(Yong Kweon Suh) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
In a microfluidic chips pressure driven flow or electro-osmotic flow has been usually employed to deliver bio-samples. Flow in the chips is usually slow and the mixing performance is poor. A micro-mixer with a rapid mixing is important for practical applications. In this study a newly designed and electro-osmotic driven micro-mixer is proposed. this design is comprised of a channel and metal electrodes attached on the local sides surface. To investigate the flow patterns each metal electrodes are properly induced with electric potential. To characterize the flow field a numerical methods were employed. To obtain the velocity field three-dimensional numerical code, CFD-ACE. Focus is given effect on the electro-osmotic flows under the local variation of the electric potential.
엔진 예혼합실의 소기 특성에 대한 이론 및 수치해석적 연구
허형석(Hyeung Seok Heo),서용권(Yong Kweon Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this paper, we present the theoretical and numerical results of scavenge characteristics in a small prechamber of an HCCI(Homogeneous Charge Compression Ignition) engine. Two theoretical models are proposed in prediction of the scavenge time and the efficiency ; one is the non-mixing models in which it is assumed that the input gas(CH₄) and the existing gas(air) do not mix with each other, and the other is the fully-mixed model in which the two gases are assumed to mix completely before ejecting to the ambient air. Focus is also given to the effect on the scavenge performance of the size of the chamber oulet.
허형석(Hyeung Seok Heo),서용권(Yong Kweon Suh) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In this paper, we present the theoretical and numerical results of a fluid coupling. A theoretical model is proposed in prediction of the dimensionless torque. Viscous flows through the coupling is simulated three-dimensionally using a commercial code, CFX 5.7. Focus is given to the effect on the performance with the geometric factor of the pump and turbine impeller. The numerical results show that the vortices in the coupling heavily depend on the performance. the dimensionless toque with speed ratio relatively have a good agreement with theoretical and numerical results.
마이크로채널 내 블록의 정렬과 구조변경에 따른 교반특성
서용권,허형석,Suh, Yong-Kweon,Heo, Hyeung-Seok 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.7
Numerical study on stirring characteristics in a microchannel with blocks arranged periodically has been performed. Viscous flows through the microchannel is simulated three-dimensionally using a commercial code, FLUENT 6.0. Focus is given to the effect on the stirring characteristics of the geometric factors including the pitch, height and angle of the block arrangement. The numerical results at low Reynolds numbers show that the particles' trajectories in the microchannel heavily depend on the block arrangement. A nonlinear dynamical tool, i.e. Lyapunov exponent, was used in analysing the mixing effect. It was found that the mixing is the most effective at a certain combination of parameter values.