• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.132-138
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• 2004

Flush inlet, which has been chosen for modem air vehicles to take advantage of structure compactness and small RCS, gives rise to some aerodynamic problems such as flow separation and distortion due to vortices which deteriorate the performance of both inlet and engine. In this study, pressure recoveries at inlet exit plane were evaluated through numerical analyses of 3D turbulent flow for various inlet shapes and flight conditions. Inlet shape was controlled by changing ramp angle and width of throat, and effects of mass flow rate and angle of attack were investigated.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.130-136
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• 2008

The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations(parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to 130 $kg/m^2s$ and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.9-21
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• 1999

The waterjet is very widely used today in propulsion system of high speed vessel but manufacturer is limited because of an efficiency and a difficulty of a manufacture on the inlet configuration of the waterjet. The importancy in designing the inlet configuration of the waterjet lies on the minimization of the cavitation which is largely affecting the efficiency. In this paper, the configuration analysis is carried out to find a optimum shape which is minimizing the cavitation using a two dimensional potential-based panel method with an inlet configuration of a flush type. Also, it is developed a direct design method finding an inlet configuration by a given pressure distributions. The numerically obtained optimum shape using this configuration analysis method show a good agreement compared to the Kashiwadani's results. It is carried out a direct design method over a lip and a ramp of an inlet configuration wish pressure distributions obtained a result of the configuration analysis and the results show a good agreement compared to original configuration.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1123-1128
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• 2009

The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations (parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to $130\;kg/m^2s$ and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.595-598
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• 2007

Urban storm water collection and conveyance systems are critical components of the urban infrastructures. During a storm event, street grate inlets are usually loaded with debris by the first-flush runoff volume. Grate inlets are subject to clogging effects. Effective interception area of grate inlets was decreased by clogging. It also decreased the interception capacity of grate inlets and increased the inundation area in street. Therefore, it is necessary to analyze the clogging characteristics and interception capacity change by clogging for appropriate design and management of grate inlets. In this study, field survey was executed to investigate debris and clogging pattern of grate inlet in 9 areas. The clogging factor with consideration of urban area characteristics was estimated with the field survey results.

• Journal of Korean Society on Water Environment
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• v.33 no.4
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• pp.474-480
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• 2017

This study was to estimate the reduction effect of nonpoint source pollutants according to the rainfall intensity and drainage of infiltration grate inlet. Soil infiltration flow was measured on-site and SS load by the filter part was calculated by the experimental data in laboratory reactor test. Soil infiltration flow was measured to be about $1m^3/hr$ in soil condition saturated with water. The filter part of the infiltration grate inlet was a hydraulic equipment unhindered by soil infiltration on the bottom of the storage tank, because the infiltration flow was measured to be about $3m^3/hr$ continuously in the closing infiltration hole condition. Infiltration flow and SS load were over about $1m^3/hr$ and 1.71 kg according to laboratory results by the filter part using the artifical sample. Therefore, the above values could be presented as the limitted value to start the reduction of filtration effect. Reduction efficiencies of SS load by the filter part for the rainfall intensity were about 87 % at 5 mm/hr and about 61 % at 10 mm/hr in consideration of one infiltration grate inlet got the drainage area about $200m^2$. The reduction efficiency of nonpoint source pollutants was very effective in the first flush rainfall. However, the reduction efficiency by rainfall density was higher than by flow.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.557-564
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• 2009

A combined sewer system can quickly drain both storm water and sewage, improve the living environment and resolve flood measures. A combined sewer system is much superior to separate sewer system in reduction of the non-point source pollutant load. However, during rainfall. it is impossible in time, space and economic terms to cope with the entire volume of storm water. A sewage system that exceeds the capacity of the sewer facilities drain into the river mixed with storm-water. In addition, high concentration of CSOs by first-flush increase pollution load and reduce treatment efficiency in sewage treatment plant. The aim of this study was to develope a processing unit for the removal of high CSOs concentrations in relation to water quality during rainfall events in a combined sewer. The most suitable operational design for processing facilities under various conditions was also determined. With a designed discharge of 19.89 m/min, the removal efficiency was good, without excessive overflow, but it was less effective in relation to underflow, and decreased with decreasing particle size and specific gravity. It was necessary to lessen radius of vortex separator for increasing inlet velocity in optimum range for efficient performance, and removal efficiency was considered to high because of rotation increases through enlargement of comparing height of vortex separator in diameter. By distribution of influent particle size, the actual turbulent flow and experimental results was a little different from the theoretical removal efficiency due to turbulent effect in device.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.55-65
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• 2006

The air and water flow distribution are experimentally studied for a round header - flat tube geometry simulating a parallel flow heat exchanger. The number of branch flat tube is thirty. The effects of tube outlet direction, tube protrusion depth as well as mass flux, and quality are investigated. The flow at the header inlet is identified as annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted configuration, most of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, however, most of the water flows through rear part of the header. The protrusion depth, mass flux, or quality does not significantly alter the flow pattern. Possible explanations are provided based on the flow visualization results. Negligible difference on the water flow distribution was observed between the parallel and the reverse flow configuration.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.22 no.3
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• pp.79-84
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• 2016

A kimchi container actively controlling $CO_2$ concentration by timely flushing of $CO_2$ gas was structured and tested in its capability and effectiveness because high $CO_2$ concentration enhances the sensory flavor of the product. The inlet and outlet valves of $CO_2$ gas were programmed to open and close allowing synchronous vent/$CO_2$ flush according to the requirements of its dissolution in the contained kimchi. During the chilled storage, the headspace of container could be maintained at desired high $CO_2$ concentration providing the preferred kimchi in sensory quality compared to control of the conventional container. However, there was no significant difference between the high $CO_2$ container and control (container simply closed with air) in kimchi quality attributes of pH, titratable acidity, total viable bacterial count, Lactobacillus sp. count and Leuconostoc sp. count. The flow rate and time interval of $CO_2$ flushing need to be adjusted considering the kimchi amount, headspace volume and ripening time. The designed system has potential to be applied in refrigerator appliances in homes and food service industry.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.888-898
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• 1998

The present study investigated the effects of the experimental parameters on the cooling characteristics of the multichip module cooled by the indirect liquid cooling method using water and paraffin slurry. The experimental parameters are mass fraction of 2.5 ~ 7.5% for paraffin slurry, heat flux of 10 ~ 40 W/cm$^{2}$ for the simulated VLSI chips and Reynolds numbers of 5,300 ~ 15,900. The apparatus consisted of test section, paraffin slurry maker, pump, constant temperature baths, flowmeter, etc. The test section made of in-line, four-row array of 12 heat sources for simulating 4 * 3 multichip module which was flush mounted on the top wall of a horizontal rectangular channel with the aspect ratio of 0.2. The inlet temperature was 20 deg. C for all experiments. The size of paraffin slurry was constant as 10 ~ 40 .mu.m befor and after the experiment. The chip surface temperatures for paraffin slurry with the mass fraction of 7.5% showed lower by 16 deg. C than those for water when the heat flux is 40 W/cm$^{2}$. The local heat transfer coefficients for the paraffin slurry with the mass fraction of 7.5% were larger by 17 ~ 25% than those for water at the first and the fourth row. The local heat transfer coefficients reached to a row-number-independent, thermally fully developed value approximately after the third row. The local Nusselt numbers at the fourth row for paraffin slurry with the mass fraction of 7.5% were larger by 23 ~ 29% than those for water.