• Journal of computational fluids engineering
• /
• v.16 no.3
• /
• pp.95-103
• /
• 2011

In the block type VHTR core, there are inevitable gaps among core blocks for the installation and refueling of the fuel blocks. These gaps are called bypass gap and the bypass flow is defined as a coolant flows through the bypass gap. Distribution of core bypass flow varies according to the reactor operation since the graphite core blocks are deformed by the fast neutron irradiation and thermal expansion. Furthermore, the cross-flow through an interfacial gap between the stacked blocks causes flow mixing between the coolant holes and bypass gap, so that complicated flow distribution occurs in the core. Since the bypass flow affects core thermal margin and reactor efficiency, accurate prediction and evaluation of the core bypass flow are very important. In this regard, experimental and computational studies were carried out to evaluate the core bypass flow distribution. A multi-block experimental apparatus was constructed to measure flow and pressure distribution. Multi-block effect such as cross flow phenomenon was investigated in the experiment. The experimental data were used to validate a CFD model foranalysis of bypass flow characteristics in detail.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.6
• /
• pp.69-76
• /
• 2013

This paper presents the development of the FCF method for the manufacturing of final products using numbers related to the minimum amount of work. The utilized product is a drum clutch, which is part of the transmission of an automobile. A double acting press is secured first and a prediction of the forming load on the practical material is made through an experiment with a plasticine model. Also, a finite element simulation using product shape and properties is performed, as well as a press experiment. A double acting press is manufactured that is suitable for a double acting experiment with a conventional hydraulic press(200 tons). A peripheral device for the press is additionally designed for experimental purposes. And, the press has as its essential points the drive speed, stroke control, etc., all of which influence the forming and is modified. Especially, a laser system is used for velocity measurement of two punches. The forming load of a practical material is predicted in order to derive a forming load formula for cold conditions on the basis of approximate similarity theory. Finite element analysis of the relative velocity ratio(RVR), etc., for most suitable flow defect(unfilling, etc.) prevention is achieved as well. The results are verified through a press experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.879-884
• /
• 2003

This paper is to experimentally investigate the effect of the through-flow and grazing-flow on the absorption performance of a perforated plate system. The experiment is performed through the systematic change of the through-flow velocity, grazing-flow velocity, incident sound pressure level, and the geometrical parameters such as the porosity and hole diameter. From the experimental results, it is found that for the nonlinear relationship between the acoustic resistance and incident sound pressure level there is no influence of the through-flow on the absorption performance, but fur the linear relationship between them there is a strong dependence of the absorption performance on the through-flow velocity. It is also shown that the absorption performance is controllable by changing the porosity and hole-diameter in size.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.6
• /
• pp.89-95
• /
• 2000

To obtain an exact flow loss in piping systems is very important in the face of efficiency anticipation and work control of plant. The object of this study is to get the flow loss through the experiment for sudden expansion and contraction part of circular pipe nozzle. The experiment in this study is performed after getting the flow loss factor for sudden expansion and contraction through preliminary experiments. It is confirmed that the results of this study agreed with the approximated equation of Ikeda and Matsuo. It is proved that flow loss factor ${\zeta}_3$for sudden expansion and contraction part of circular pipe is dependent on $L/D_1$in these experimental conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.10 no.5
• /
• pp.630-639
• /
• 1998

The present research aimed at development of a computer code for the optimal design of ventilation system based on one-dimensional analysis of the air flow. Model experiment and three-dimensional flow analysis have been implemented to determine loss coefficients that were needed for the optimization technique. A research on optimum shape of ventilation shaft has been also carried out through the three-dimensional analysis of the flow.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.1
• /
• pp.43-57
• /
• 2002

This paper introduces an analysis method to predicting the flow characteristic of flow field around otter board In order to develope a high performance model. In this experiment, it is used a numerical analysis of flow field through CFD(Computational Fluid Dynamic), PIV method in which quantitative, qualitative evaluation is possible. In this experiment, it is used PIV method with flow filed image around otter board in order to analysis of flow characteristic. The result compared flow pattern with analysis result through CFD and also measurement result of lift and drag force coefficient carried out in CWC(Circulating Water Channel). The numerical analysis result is matched well with experiment result of PIV in the research and it is able to verify In the physical aspect. The result is as follows ; (1) It was carried out visibility experiment using laser light sheet, and picture analysis through PIV method in order to analysis fluid field of otter-board. As a result, the tendency of qualitative fluid movement only through the fluid particle's flow could be known. (2) Since PIV analysis result is quantitative, this can be seen in velocity vector distributions, instantaneous streamline contour, and average vorticity distributions through various post processing method. As a result, the change of flow field could be confirmed. (3) At angle of attack 24$^{\circ}$ where It Is shown maximum spreading force coefficient, the analysis result of CFD and PIV had very similar flow pattern. In both case, at the otter-board post edge a little boundary layer separation was seen, but, generally they had a good flow (4) As the result of post processing with velocity vector distributions, instantaneous streamline contour and average vorticity distributions by PIV, boundary layer separation phenomenon started to happen from angle of attack 24$^{\circ}$, and from over angle of attack 28$^{\circ}$, it happen at leading edge side with the width enlarged.

• Journal of Mechanical Science and Technology
• /
• v.19 no.2
• /
• pp.704-715
• /
• 2005

In this study, to investigate in-cylinder tumble or swirl intake flow of a gasoline engine, the flow characteristics were examined with opening control valve (OCV) and several swirl control valves (SCV) which intensify intake flow through steady flow experiment, and also turbulent characteristics of in-cylinder flow field were investigated by 2-frame cross-correlation particle image velocimetry (PIV) method. In the investigation of intake turbulent characteristics using PIV method, the different flow characteristics were showed according to OCV or SCV figures. The OCV or SCV installed engine had higher vorticity and turbulent kinetic energy than a baseline engine, especially around the wall and lower part of the cylinder. Above all, SCV B type was superior to the others. About energy dissipation and reynolds shear stress distribution, a baseline engine had larger loss than OCV or SCV installed one because flow impinged on the cylinder wall. It should be concluded, from what has been said above, as swirl component was added to existing tumble flow adequately, it was confirmed that turbulent intensity was enlarged, flow energy was conserved effectively through the experiment. In other words, there is a suggestion that flow characteristics as these affected to in-cylinder combustion positively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.163-167
• /
• 2003

This paper is to experimentally investigate the effect of the through-flow on the absorption performance of a perforated plate system. The experiment is performed through the systematic change of the through-flow velocity, incident sound pressure level, and the geometrical parameters such as the porosity and hole diameter. From the experimental results, it is found that fur the nonlinear relationship between the acoustic resistance and incident sound pressure level there is no influence of the through-flow on the absorption performance, but for the linear relationship between them there is a strong dependence of the absorption performance on the through-flow velocity. It is also shown that the absorption performance is controllable by changing the porosity and hole-diameter in size.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.9
• /
• pp.265-278
• /
• 2016

In this study, an ascending capability experiment was performed with largemouth bass and bluegill, which are exotic fish species inhabiting (the freshwaters) in Korea. The experiment was performed by dividing the subject fish into four groups according to their size and at four flow rates for each group. The number of fish passing through a reference line was analyzed by recording videos, and their swimming and ascending capabilities were observed by the naked eye. The number of fish passing through the reference line did not include those returning downstream within five minutes due to the high flow rate. The flow rate used for the analysis was the mean of the flow rate values measured at the left bank, the right bank, and in the middle of the stream. The results showed that the number of exotic fish migrating upstream decreased as the flow rate increased, regardless of the species and size of the fish. The comparison between the fish species showed that the ascending capability of bass was higher than that of bluegill, but the difference was not significant when considering the difference in the size of the fish. In addition, the upper limit flow velocity allowing the ascending of the exotic fish species was 1.11 m/s, when considering the fish returning to the downstream after the upstream migration and experimental error. The results of the experiment may be used as fundamental data for the blocking of fish and the management of exotic fish species by means of a high flow rate current. Further experiments, verification, and monitoring may need to be conducted continuously to determine whether the fish are able to pass through the reference line at a high flow rate, when they attain a high or cruising velocity. Additionally, the reaction of the fish species should be investigated by considering the response to external forces as well as pressure differences due to the flow rate.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.8 no.1
• /
• pp.101-108
• /
• 2002

This experimental study was performed to investigate internal flow and unsteady flow characteristics using a model for actual shape of a Plate heat exchanger and visualization of flow through the particle image velocimetry. Seven Reynolds numbers were selected by calculation with the height of grooved channel and sectional mean velocity of inlet flow in the experiment, and instantaneous velocity distributions and flow characteristics were experimently investigated. 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 in the experiment. The sheared mixing layer, in the boundary between the triangular groove and the channel. affected main flow to raise turbulent in the channel.