Flow visualization of Butterfly valve is tested five cases(15°, 30°, 45°, 60° and 90°) of vlave opening angle. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics of butterfly valve about discharge of dam.. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated each cases. The results from flow visualization using PIV through the video which do not contain a cavitation phenomenon was confirmed in accordance with the valve opening. Performs valve opening and the flow properties of the Karman vortex generated by the frequency analysis is 90° was calculated the frequency of the butterfly valve applied to the actual dam. Butterfly valve for the emergency discharge valve is susceptible to cavitation caused by the valve opening 90° and repeat the cycle in the valve side of the vortex emission system is a high possibility of damage due to fatigue.

본 연구에서는 저장볼트(storage vault)의 실험을 위하여 1/4 축소모델 내 튜브의 적정 발열량을 선정하고자 상사해석을 수 행하였다. 저장볼트에 대한 열 및 유동 해석을 우선적으로 수행하였고, 크기를 1/4로 축소한 저장볼트에 대하여 동일한 전 산해석을 수행하였다. 전산해석 결과를 바탕으로, 제안된 무차원수를 비교하여 원형모델과 온도분포와 유동분포가 유사하 게 되는 발열량을 선정하였다. 1/4 축소 저장볼트 내 튜브의 열유속이 1.3배일 때, 원형 저장볼트와 1/4 축소 저장볼트의 온 도장 및 유동장이 상사되었다. 이 때, 1/4 축소 저장볼트 내 발열량은 약 190 W이다.

The study on ice thermal storage system is to improve total system performance in actual air-conditioning facilities. This paper deals with experimental research to observe the characteristics of heat flow and the effect of ice thermal storage in case of three sizes of ice ball, which are included identification of ice thermal extraction. Diameters of three ice ball was 103mm, 96mm, and 76mm is equivalent to 0.45, 0.50 and 0.55 in porosity respectively. Also inlet geometric parameters are the perforator and distributor. Flow rate of brine were 2LPM, 4LPM and 6LPM and the temperature difference in dynamic parameter are 8℃, 10℃ and 12℃. Flow rate of brine used the liter per minute(LPM) for liquid measurement applications. The effect of brine flow rate on efficiency increased as the temperature difference and porosity increased. An adaption of a long-term storage in case of smaller porosity(ɛ=0.45) was available through experiments of outlet temperature responses.

Silicon carbide(SiC) layer is particularly important tri-isotropic (TRISO) coating layers because it acts as a miniature pressure vessel and a diffusion barrier to gaseous and metallic fission products in the TRISO coated particle. The high temperature deposition of SiC layer normally performed at 1500-1650˚C has a negative effect on the property of IPyC layer by increasing its anisotropy. To investigate the feasibility of lower temperature SiC deposition, the influence of deposition temperature on the property of SiC layer are examined in this study. While the SiC layer coated at 1500˚C obtains nearly stoichiometric composition, the composition of the SiC layer coated at 1300-1400˚C shows discrepancy from stoichiometric ratio(1:1). 3-7μm grain size of SiC layer coated at 1500˚C is decreased to sub-micrometer (＜ 1μm) -2μm grain size when coated at 1400˚C, and further decreased to nano grain size when coated at 1300-1350˚C. Moreover, the high density of SiC layer (≥3.19g/cm3) which is easily obtained at 1500˚C coating is difficult to achieve at lower temperature owing to nano size pores. the density is remarkably decreased with decreasing SiC deposition temperature.

In this study, the ventilation of duct is simulated by CFD and thermal changes on the seat surface are measured experimentally. These models are the improved duct and the existing one installed at the real seat in order to test the thermal change 1 minute later. The seat with the existing duct has the temperatures of 26℃ and 25℃ on lumber and femoral parts respectively. However, the seat with the improved duct has the temperature of 1℃ lower than the seat with the existing duct. This result contributes to develop the improved duct. Hereafter, the methods used in this study are expected to be useful at checking the flow resistance loss of the ventilation seat duct and assessing the flow channel design

We have performed CFD simulation and analyzed flow and concentration fields for the basic data of the ventilation system for removing pollutants which were produced in a lecture room. The flow patterns indicated differently according to the arrangement of openings and the concentration distribution of pollutants were showed higher and lower because of the effect of that flow patterns. In the case of arranging the openings to the upper and lower side, the stagnation appearance of flow formed in the interested space. In the case of arranging the openings to the right and left side, the stagnation of high concentration pollutants appeared in the middle area of the interested space. On the increasing exhaust velocity, the distribution of pollutants appeared similar to the normal case, but the concentration of pollutants were lower.

Carousel type rotating molding machine is a plastics molding method that is adapted to producing relatively large and seamless parts which are partially or totally enclosed. So it is used to produce the big septic tank, storage tray, icebox, central reservation and so on. Rotating molding method are Rock and Roll, Shuttle, Carousel type, etc. In this study, to develop Carousel type rotating molding machine, its 3D model has designed. Also, to confirm the performance of this model, the theoretical and experimental analysis were carried out under condition of shape and structure of rotating unit and heating unit in molding machine

Translucent alumina is a potential candidate for high temperature application as a replacement of the glassor polymer. Recently, due to the increasing demand of high power light emitting diode (LED), there is a growing inter-est in the translucent alumina. Since the translucent property is very sensitive to the internal defect, such as voids insideor abnormal grain growth of sintered alumina, it is important to fabricate the defect-free product through the fabricationprocess. Powder injection molding (PIM) has been commonly applied for the fabrication of complex shaped products.Among the many parameters of PIM, the flowability of powder/binder mixture becomes more significant especially forthe shape of the cavity with thin thickness. Two different positions of the gate were applied during PIM using the disctype of die. The binder was removed by solvent extraction method and the brown compact was sintered at 1750oC for3 hours in a vacuum. The flowability was also simulated using moldflow (MPI 6.0) with two different types of gate.The effect of the flowability of powder/binder mixture on the microstructure of the sintered specimen was studied withthe analysis of the simulation result.

본 연구에서는 수중 삼각형상구조물의 경사도와 레이놀즈 수 변화에 따른 구조물 주위의 유동특성을 분석하였다. 모델링한 삼각형상구조물 주위의 유동장은 회류수조에서 가시화실험과 입자영상유속계(PIV)를 이용하여 계측하였다. 실험결과 경사각이 45°인 삼각형상구조물이 레이놀즈 수 Re=2.9×10³에서 구조물 높이의 2.7배까지 상승하는 속도성분이 나타났다. 레이놀즈 수가 일정할 때 경사각이 클수록 구조물 후방에 하강하는 속도성분이 크게 나타났고, y/hs=1.75이상의 영역에서는 경사각과 레이놀즈 수가 구조물 후방의 유동형태에 변화를 주지 않았다.

In this paper, we analyzed the characteristics of the mass flow rate and velocity of the refrigerant in response to a change in the number of holes and the diameter size(Type-1～4) of the valve guide refrigerant to flow from Pc to Ps when the pressure is constant. Type-1 is 40% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-2 is 64% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-3 is 50% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate. Type-4 is 47% higher mass flow flowing in the direction of Ps as compared with the Pc mass flow rate.

A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The porosity and heat transfer coefficient of filler material as well as inlet velocity of heat transfer fluid are selected as simulation parameters. The porosity is varied as 0.2, 0.5, and 0.8 to account for the effect of filler granule geometry. Two levels of the heat transfer coefficient is adopted to assess the heat transfer between heat transfer fluid and filler material. The inlet velocity is varied as 0.00278, 0.0278, and 0.278m/s. As both of the porosity and the heat transfer coefficient increase, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As the inlet velocity increases, the penetration depth of the heat transfer fluid increases proportionally.

극저온 액체 상태의 LNG는 주거용과 산업용으로 공급되기 전에 가스 상태로 변환된다. 이러한 재가스화 과정 중에 LNG는 83.7×104 kJ/kg 정도의 많은 냉열에너지를 제공한다. 이 냉열에너지를 일부 선진국들에서는 질소, 수소, 헬륨과 같은 극저온 유체들의 액화, 제빙 및 냉방시스템에 이용하고 있다. 따라서 우리나라에서도 인천, 평택 및 통영 LNG 인수기지 주변에 LNG의 냉열에너지를 이용한 냉열에너지 회수시스템을 설립할 필요가 있다. 여기서는 저열유속상태에서 상변화를 동반하는 LNG의 유동거동 특성을 파악하기 위해 LNG의 85 %를 차지하는 메탄을 작동유체로 사용하였다. 또한 본 논문은 극저온 열교환기 내부를 흐르는 메탄과 질소, 프로판, R11 및 R134a의 유동경계에 영향을 주는 관 직경, 관의 경사각도 및 포화압력의 효과를 보여준다. 또한 여기서 얻어진 이론적 연구결과와 기존의 실험 데이터와도 비교 되었다. 그리고 메탄의 유동경계에 주는 파이프의 경사각도의 영향은 매우 큼을 알 수 있었다.

In this study, numerical simulation has been conducted to investigate flow characteristics in air supply room for container vessels by a 3-dimension numerical simulation. A commercial CFD program, FLUENT, is used on the analysis. It is shown that the air supply efficiency in this room can be improved by changing position of axial fan, even though other conditions still remain unchanged.

A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The interfacial area density and inertial resistance of filler material are selected as simulation parameters. The interfacial area density is varied as 800, 2000, and 4000 1/m. The inertial resistance is varied as 1, 3, and 5 1/m. When the interfacial area density increases from 800 to 4000 1/m, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As inertial resistance increases from 1 to 5, both of the temperature and fluid flow pattern changes considerably.

수치모델을 이용하여 한국 동해 용승역의 유동특성에 대해 연구하였다. 용승을 일으키는 주요 인자인 바람, 해류 등을 파악하여 동해 연안역의 시·공간적인 분포와 용승유량을 정량적으로 산정한다. 연구해역인 동해에서 대·소기의 조류는 흐름의 크기가 차이가 났으나 창조류 시 남향하고 낙조류 시 북향하는 흐름을 보였다. 취송류는 연안을 따라 북향하는 흐름을 보이며 표층에서는 외해로 발산하고 저층에서는 연안으로 보상하는 흐름을 나타낸다. 취송류에 의한 용승발생분포는 평균 0.1cm/s정도의 상승류가 동해 전 연안에 걸쳐 넓게 분포하며 표층에서 강하고 저층으로 갈수록 좁게 분포하는 경향을 보였다. 상승류의 최대 유속은 약 1.4cm/s 정도로 영덕, 후포, 구룡포 그리고 기장의 연안에서 나타났다. 또한 본 연구에서는 용승해역에서 용승유량을 정량적으로 산정하여 밝혀낸다.

In this study, we modeled a actual shape of a plate heat exchanger into triangular grooved channel and tried to examine flow characteristics experimentally by particle image velocimetry. Five Reynolds numbers were selected with the height of grooved channel and sectional mean velocity of inlet flow. As a result, the triangular grooved channel had a compound flow consisting of the flow in lower channel and the groove flow receiving shear stress by the channel flow. The sheared mixing layer, in the boundary between the triangular groove and the channel, affected main flow to raise turbulent in the channel.