• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.70-73
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• 2005

The HANARO, multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and is under developing a target handling tool for loading and unloading it in a circular flow tube (OR-5). A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under the reactor normal operation. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube after unloading the target. This paper describes an analytical analysis to calculate the flow distribution in the core of the HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of the HANARO were not adversely affected.

• 한국기계가공학회지
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• 제19권1호
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• pp.11-18
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• 2020

The emergence of the flow-through cell (FTC) method has made up for the limitations of previous dissolution test methods, but the high cost of the FTC dissolution devices have seriously hindered the progression of research and application of the FTC. This new design uses a peristaltic pump to simulate the sinusoidal flow rate of a piston pump. The flow profile of each peristaltic pump was sinusoidal with a pulsation of 120 ± 1 pulses per minute, and the flow rate ranged from 1.0 - 36.0 mL/min. The flow control of each channel was adjusted independently so the flow errors of the seven channels were close to 2%. The structure of the system was simplified, and the cost was reduced through manual sampling and immersing the FTC in a water bath. The dissolution rate of the theophylline and aminophylline films was determined, and good experimental results were obtained.

• 한국유체기계학회 논문집
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• 제16권1호
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• pp.40-46
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• 2013

Recently, the duct system with a cross flow fan was used to improve the ventilation in various industrial fields. For the efficient ventilation, it is necessary to design the duct system based on the flow characteristics around the cross flow fan. In the present study, the flow characteristics around a cross flow fan in the ventilation duct were predicted by using the moving mesh and sliding interface techniques for the rotation of blades. To design the duct system with the high performance of ventilation, the CFD simulations were repeated with the revised duct model based on the DOE. With the numerical results of flow rate through the ventilation duct with various geometric parameters, the optimized geometry of ventilation duct to maximize the flow rate was obtained by using the Kriging approximation method. From the performance curves of cross flow fan in the original and optimized models of ventilation duct, it was observed that the flow rate through the optimized model is about 16 percent larger than that through the original model.

• 한국전산유체공학회지
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• 제10권4호통권31호
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• pp.66-71
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• 2005

HANARO, a multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and a target handling tool is under development for loading and unloading it in a circular flow tube (OR-5) of HANARO. A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under a normal operation of the reactor. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube. This paper describes an analytical analysis to calculate the flow distribution in the core of HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of HANARO were not adversely affected.

• 대한기계학회논문집B
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• 제20권9호
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• pp.2924-2932
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• 1996

As the environmental pollution can be greatly reduced and the waste heat can be also recovered through a combustion of municipal solid waste, the incineration begins to be highlighted recently in our country. But it is very difficult to be operated with constant combustion conditions for a long time as the domestic waste is composed of various components, contains a large percentage of water, and has a low heating value. Therefore, the cold flow test and partial hot flow test were conducted in the incinerator by use of injection angles of a secondary air affecting fluid flow as the first action to maintain the optimum combustion conditions. A model to a scale of 1:10 was designed and manufactured through the similarity of model and prototype flows. Velocities and temperatures were measured through the experiment. From the results, fluid flows of secondary air obtained from partial hot flow test correspond almost well with those of main flow obtained from cold flow test. Consequently, injection angles of secondary air are proved to affect main flow decisively.

• 설비공학논문집
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• 제23권2호
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• pp.132-138
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• 2011

In the present article, we investigate numerically turbulent flow of air through compound rectangular channels. Large eddy simulation(LES) is employed for unsteady turbulence modeling. LES gives better predictions for the axial mean velocity distribution than those of other turbulent models. Strong large-scale quasi-periodic flow oscillations are observed in most of the geometries investigated. Such large-scale flow oscillations in compound rectangular channels are similar to the quasi-periodic flow pulsation through the gaps between fuel rod bundle in nuclear reactor. It exists in any longitudinal connecting gap between two flow channels. The frequency of this flow oscillation is determined by the geometry of the gap. The large scale cross motions through the rectangular compound channels induce significant heat transfer enhancement of the compound channel flow.

• 설비공학논문집
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• 제10권1호
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• pp.118-128
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• 1998

Capillary and short tube orifice have been widely used as an expansion device in refrigeration and air-conditioning system. To improve the system performance, expansion devices need to be optimized with the components of a refrigeration system. In the present study, a numerical model for a capillary, which can predict properties along a tube and flow rate through a tube, was developed by assuming homogeneous two-phase flow, A semi-empirical flow model that can be used to evaluate the flow rate through a short tube orifice was also developed by summarizing the experimental data. Finally, the results of the numerical model for capillaries were compared with those of the semi-empirical model for short tube orifices to verify dominant flow factors for the expansion devices.

• 설비공학논문집
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• 제8권1호
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• pp.45-54
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• 1996

An experimental investigation on the two-phase flow through tube orifices was performed with the refrigerant mixture of R32/125/134a(30/10/60). A series of tests were conducted to generate wide range of data at varying operation conditions with four short tubes. The tests include both single and two-phase flow conditions at the inlet of the short tube with different oil concentrations. Experimental data were presented as a function of major operating parameters and short tube diameter. Based on test results and data analysis, a semi-empirical flow model was developed to predict the mass flow rate through short tube orifices with a given set of conditions. The flow model was formed to cover both single and two-phase flow at the inlet of short tube with considering the effects of oil concentration.

• 터널과지하공간
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• 제6권1호
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• pp.30-38
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• 1996

A two dimensional analysis program for groundwater flow in fractured network was developed to analyze the influence of discontinuity characteristics on groundwater flow. This program involves the generation of discontinuities and also connectivity analysis. The discontinuities were generated by the probabilistic density function(P.D.F.) reflecting the characteristics of discontinuities. And the fracture network model was completed through the connectivity analysis. This program also involves the analysis of groundwater flow through the discontinuity network. The result of numerical experiment shows that the equivalent hydraulic conductivity increased and became closer to isotropic as the density and trace length increased. And hydraulic head decreased along the fracture zone because of much water-flow. The grouting increased the groundwater head around cavern. An analysis of groundwater flow through discontinuity network was performed around underground oil storage cavern which is now under construction. The probabilistic density functions(P.D.F) were obtained from the investigation of the discontinuity trace map. When the anisotropic hydraulic conductivity is used, the flow rate into the cavern was below the acceptable value to maintain the hydraulic containment. But when the isotropic hydraulic conductivity is used, the flow rate was above the acceptable value.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1389-1394
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• 2004

Experiments were done for the unsteady flow in a counter rotating axial flow fan near peak efficiency and stall point. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional passage flow patterns were investigated through the acquired data by the $45^{\circ}$ inclined hot-wire. Comparison of flow characteristics between two different operating conditions such as tip vortex, secondary flow and turbulence intensity were performed through the analyses of axial, radial and tangential velocity distributions. As a result, tip vortex and secondary flows are enforced and measured obviously at stall point.