• 한국전산유체공학회지
• /
• 제8권2호
• /
• pp.16-23
• /
• 2003

A numerical study of the mixing of two fluids(pure water and a solution of glycerol in water) in a microchannel was carried out. By varying the glycerol content of the glycerol/water solution, the variation in mixing behavior with changes in the difference of the properties of the two fluids(e.g., viscosity, density, diffusivity) was investigated. The mixing phenomena were tested for three micromixers: a square mixer, a three-dimensional serpentine mixer, and a staggered herringbone mixer. The governing equations of continuity, momentum and solute mass fraction were solved numerically. To evaluate mixing performance, a criterion index of mixing of mixing uniformity was proposed. In the systems considered, the Reynolds numbers based on averaged properties were 1 and 10. For low Reynolds number (Re = 1), the mixing performance varied inversely with mass fraction of glycerol due to the dominance of molecular diffusion. The mixing performance by diffusion deteriorated due to a significant reduction in the residence time of the fluid inside the mixers.

• Journal of Advanced Marine Engineering and Technology
• /
• 제26권5호
• /
• pp.589-595
• /
• 2002

Fluid mixing is ubiquitous and essential in many natural and industrial systems. Understanding the mixing processes that occur in these diverse systems is essential for predicting many aspects of practical importance. The objective of this study was to develop a new mixing element and to perform the experimental investigation of flow and mixing in a static mixer that is equipped the new element and the others. Glycerin and gear oil were used as mixing fluids. Pressure drops across the static mixer elements of different designs and different numbers were measured using a hydraulic manometer The axial and cross-sectional views of tracer mixing were photographed using a digital camera. The pressure drops of SSM mixer were about 20% less than that of Sulzer mixer whereas the mixing performance of SSM mixer was not so good as that of Sulzer mixer

• 한국전산구조공학회논문집
• /
• 제30권4호
• /
• pp.363-370
• /
• 2017

본 논문에서는 원통형 혼합기를 대상으로 블레이드의 각도, 길이, 개수 및 블레이드와 탱크 바닥과의 간극을 설계변수로 선정하고, 각각의 설계변수가 혼합성능에 미치는 영향을 분석하였다. 이산요소법을 이용하여 임펠러 회전에 의한 고체 입자의 혼합공정을 해석하였으며, 혼합지수를 도입하여 혼합성능을 정량적으로 평가하였다. 다양한 설계변수의 조합을 고려한 실험계획법으로 설계변수의 주효과와 교호작용을 분석함으로써, 블레이드 각도가 입자의 혼합성능에 가장 지배적인 영향을 미치며 간극의 영향은 상대적으로 작다는 결론을 도출할 수 있었다. 또한 가장 우수한 혼합성능을 보이는 설계변수의 조합을 제시하였다.

• 한국기계가공학회지
• /
• 제16권5호
• /
• pp.157-165
• /
• 2017

The high-pressure resin transfer molding (HP-RTM) technology has been commercialized for fast production of fiber reinforced composite materials. The high-pressure mixing head was one of the most core component of the HP-RTM process. In this study, a mixing head was systematically designed, manufactured and evaluated. This mixing head was composed of a nozzle, a mixing chamber, a cleaning piston part, and an internal mold release part. In actual, a straight-type structure was newly designed instead of the conventional L-type structure for improving the maximum mixing pressure and mixing ratio precision. The performance of mixing head was showed maximum mixing pressure of 15.22MPa and mixing ratio precision of 0.12%. CFRP molding experiments were successfully obtained a 6~11 laminating carbon sheet using HP-RTM presses and specimen molds.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2811-2816
• /
• 2007

We conducted a numerical study of AC-electroosmotic (alternating current) effect on the fluid flow and mixing in a 3-D microchannel. The microchannel used as an efficient micro-mixer is composed of a channel and a series of pairs of electrodes attached in zigzag pattern on the bottom wall. The AC electric field is applied to the electrodes so that a steady flow current takes place around the electrodes. This current is flowing across the channel and thus contributing to the mixing of the fluid within the channel. We performed numerical simulations by using a commercial code to obtain a steady flow field. This steady flow is then used in evaluation of the mixing performance via the concept of mixing index. It was found that good combination of two kinds of electrode, which gave us a good mixing, is not simple harmonic. And when the length ratio of these two kinds of electrode is 2:1, we can get the best mixing effect.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1516-1521
• /
• 2004

Mixing in Y-channel micro mixer is analyzed through computational fluid dynamics. In the case of passive mixing, we investigate the effect of geometric parameters on the mixing efficiency, such as shape of throttling geometry and angle between two inlets. Mixing performance improves as two fluids join not just horizontally but both vertically and horizontally, and it also improves when channel follows throttling shapes. A numerical results substantiate the highly efficient mixing performance. It is highly beneficial to fabrication process since the proposed throttling geometry is simple, but allows high mixing ratio.

• 항공우주시스템공학회지
• /
• 제8권1호
• /
• pp.30-35
• /
• 2014

This study has been conducted to develop an ejector system applied in the aircraft engine-bay ventilation system. Tandem-Ejector was selected as a component of ventilation system because it could achieve high ventilation performance in spite of motive flow with small flow rate. Tandem-Ejector is composed of a primary nozzle and two mixing ducts ($1^{st}$ mixing duct and $2^{nd}$ mixing duct). In this study, 1-D Tandem-Ejector model has been built with conservation laws and isentropic relation for 1-D ejector sizing and performance prediction. Computational Fluid Dynamics(CFD) has been conducted to investigate ejector performance and flow characteristics in the ejector. Also, Tandem-Ejector performance tests have been conducted to obtain ejector pumping performance and to investigate stand-off (gap between primary nozzle and $1^{st}$ mixing duct inlet) effect on ejector pumping performance.

• 한국도로학회논문집
• /
• 제17권5호
• /
• pp.67-73
• /
• 2015

PURPOSES : This study was conducted to derive the optimum mixing ratio of phosphorescent pigment for the development of phosphorescent line marking. METHODS: In this study, we utilized a literature review and case study methodology, to describe the domestic and foreign state of practice for the production and mixing of phosphorescent pigment for use in line marking. The optimal mixing ratio was derived by comparing the reduction in luminance over time for the various phosphorescent pigment mixing ratios identified in the literature. In addition, performance and construction characteristics were analyzed using field testing techniques. RESULTS : The results were as follows: 1) the results of the luminance performance standards tests showed that all of the phosphorescence test specimens satisfied the phosphorescent fire protection standard. As the phosphorescent pigment mixing ratio increased, the luminance value increased, 2) the luminance reduction rate was minimum at the mixing ratio of 50%. However, when compared to a mixing ratio 40%, a small difference was recorded, the luminance reduction rate from the mixing ratio of 40% is judged as being converged. Therefore, in view of the economic efficiency, it was determined that the optimal mixing ratio was 40%, 3) as a result of construction on the field, a mixing ratio of 40% was found to have a higher luminance value than the general line marking for up to three hours after sunset, 4) it was found that the phosphorescent line markings without glass beads spraying had a higher luminance value than the phosphorescent line markings with glass beads spraying. CONCLUSIONS : Through the results of the basic experiments of the line markings obtained by blending a phosphorescent pigment, the results could be applied to play an important role in the development of phosphorescent line marking paint technology and in establishing application planning for on-site construction characteristics.

• 한국가시화정보학회지
• /
• 제16권2호
• /
• pp.53-58
• /
• 2018

This paper presents an electromagnetically driven microrobot for the enhancement of mixing performance in high viscous liquid media such as blood and bone marrow. First, an electromagnetic system was fabricated, and the magnetic flux density generated from the system was compared with the theoretical value. Second, the reciprocating motion of the microrobot was demonstrated in microchannel using electromagnetic system. As a proof of concept, the mixing performance by the electromagnetically driven microrobot in high viscous liquid was investigated using safranin solution. As a result, it was completely mixed within 140 s with the reciprocating motion of the microrobot while it took 1680 s for natural diffusion. In addition, the mixing efficiency was quantitatively evaluated through a mixing index obtained by an image analysis. The proposed method provides not only wireless actuation of a microrobot with a simple design but also high mixing performance in variety of high viscous liquid media.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
• /
• pp.69-72
• /
• 2011

The purpose of this study is to identify basic property of porous concrete using cooper slag as fine aggregate. The specimens were made with cooper slag with various mixing ratio(10, 20, 30, 50%), porous concrete and porous concrete containing river fine aggregate and crushed fine aggregate, which W/B ratio fixed 0.25. Compressive strength, Flexural strength, coefficient of permeability. From the test results, various fine aggregate mixing ratio improves compressive strength and flexural strength, but cooper slag fine aggregate mixing ratio over 20%, concrete indicates trend to decrease performance of permeability. Concrete containing fine aggregate is improved the performance of permeability and strength compared to other specimen, when age 28days, and cooper slag mixing ratio less than 20% concrete indicates better performance than cooper slag mixing ratio 20% over.