• 한국분무공학회지
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• 제21권1호
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• pp.13-19
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• 2016

Atmospheric spray characteristics were experimentally compared between liquid-gas and liquid-liquid sprays of a pintle injector. In order to study spray characteristics, water and air were used as the simulants and the visualization technic was adopted. Spray images were acquired by using a backlight method by a high-resolution CMOS camera. As a result, when the pintle opening distance increased, liquid sheets became unstabled and fluttering droplets increased. In the liquid-gas case, the breakup performance increased as the pressure of gas injected from the annular orifice increased. In the liquid-liquid case, atomization efficiency decreased as the pressure of liquid injected from the annular orifice increased. Spray angles presented a similar trend between two cases. At the same momentum ratio, the spray angle of liquid-liquid case was lower than the angle of liquid-gas case.

• 한국분무공학회지
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• 제25권1호
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• pp.1-7
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• 2020

In the common rail fuel injection system, which is the core of diesel high efficiency and NO_X reduction, injection strategies such as high pressure injection of fuel, accurate injection rate control, and multistage injection are important to increase fuel atomization. In this study, the bypass type piezo injector for the electronic control based common rail injection system applied to diesel fuel vehicle was studied. In particular, the injection rate and internal fuel flow characteristics of the high-pressure injector according to the piezo stacking number and applied voltage were analyzed by theoretical numerical method. When the applied voltage changes, it is determined that additional fuel flow through the bypass compensates for the reduced valve driving force due to the change in the driving voltage.

• 한국자동차공학회논문집
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• 제2권6호
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• pp.50-56
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• 1994

This is an experimental study on the performance characteristics of Diesel Automobile with ultrasonic fuel feeding system. For this purpose, ultrasonic fuel feeding system was made and atomization characteristics was measured. Base on this result, carried out engine dynamometer test to investigate the performance characteristics of diesel automobile with ultrasonic fuel feeding system in comparison with conventional diesel fuel injector. The results are as follows. 1) In the spray characteristics test, fuel particle sizes were decreased about 11%~21%. 2) In engine dynamometer test, -The power was increased about 5%~11%. -The thermal efficiency was improved about 6%~11%. -The specific fuel consumption was improved about 6%~19%. -The smoke concentration was decreased about 11%~50%.

• 한국분무공학회지
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• 제7권1호
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• pp.21-28
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• 2002

The mixing of propellant and its mass distribution of unlike-doublet impinging injector, which is known to affect the combustion efficiency significantly, have been studied using PLIF(Planar Laser Induced Fluorescence). The results show that fuel jet penetrates considerably into the oxidizer jet at impinging point as variation of momentum ratio. and then stream flows inclined because of variation of momentum ratio. Consequently, the mixing efficiency shows that maximum efficiency is at MR=3. after MR=3, mining efficiency decreases slightly.

• 한국분무공학회지
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• 제9권3호
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• pp.15-21
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• 2004

The removal of the dusts in the subway stations, tunnels, factories and buildings becomes issue for comfortable indoor and outdoor conditions. There has been used an automatic self-cleaning filter system to collect the dusts. In general, the collected particles are removed by water spray nozzles. The new design for improving the cleaning efficiency of collected dusts and reducing the supplied water is the concept of the plane array of demister filters and the twin-fluid nozzle for mixing compressed air and water in the automatic self-cleaning filter system. Results show that the cleaning efficiency of twin-nozzle filter systems is 99.1%, compared to 47% in the conventional filter system. Therefore the automatic self-cleaning filter system using twin-fluid nozzle filter systems reduces water supplied in the filter system, and increases cleaning efficiency and drying efficiency.

• 한국유체기계학회 논문집
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• 제7권6호
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• pp.7-14
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• 2004

A new electrostatic rotary atomizing painting equipment using air turbine was developed for high transfer efficiency. Based on the overall design requirements of painting equipment, basic design specifications of the equipment parts such as air turbine and atomizing disk ate defined from the present conceptual design model. Air turbine is designed with the section profile of NACA airfoil, and its internal flow field is analyzed by commercial CFD code. Atomizing disk is designed to achieve the ligament type spray of paint with the use of visualization technique. Various experiments and tests are conducted to investigate the spray and the transfer characteristics of newly-designed painting equipment, and the measurement results are compared with the those of conventional painting equipments. The comparison results show the present painting equipment is superior to the conventional ones in the aspects of transfer efficiency and coating surface characteristics.

• 한국분무공학회지
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• 제15권4호
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• pp.177-181
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• 2010

This paper has designed a mixing enhancement apparatus called Lobed-plate and Step-plate and comparatively calculated desulfurization efficiency of when its shape was changed. The parameters used at this time were the shape, SR ratio and the number of nozzles of the mixing enhancement apparatus and comparatively analyzed desulfurization efficiency according to these parameters. As a result, the Step-plate appeared as more highly by around 4% than Lobed-plate in desulfurization efficiency according to the shape of the mixing promotion apparatus, and when the desulfurization efficiency as a SR ratio is considered, it appeared highly by an average of 5% when the SR ratio is 3 rather than 2. As a result of comparing desulfurization efficiency by fixing the SR ratio and setting the number of nozzles as 4 pieces and 6 pieces, there was no big change in desulfurization efficiency when the SR ratio is 2, but it could be confirmed to improve by around 5% when the SR ratio is 3 when time passed 8 seconds.

• 한국분무공학회지
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• 제14권1호
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• pp.1-7
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• 2009

This study carried out numerical analysis of flow field of combustion gas and sorbent to test sorbent efficiency of DSI process. To provide rapid mixing for increase utilization rate of sorbent, streamwise vorticity can be introduced into the flowing streams by other means; for example, by installing vortex generators immediately downstream of the wavy trailing edge. Computing results show that the degree of sorbent dispersion depends strongly on duct structure. Highest dispersion efficiency received when vortex generator was installed inside of duct. The results presented in this study a optimum condition for the development of practical DSI process.

• 한국분무공학회지
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• 제21권1호
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• pp.7-12
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• 2016

In this study, to research in-cylinder flow characteristics of spark-ignited engine with intake valve closing timing change for Miller cycle. 3D simulation study were used 6 different intake valve profile with $CAD10^{\circ}$ gap for retard intake valve closing timing. Comparison of In-cylinder flow pattern characteristic were accompanied between Base and LIVC. And the efficiency of volume and the work of compression were analyzed with simulation study. When intake valve closing angle was retarded in $CAD50^{\circ}$, the pressure in cylinder was decreased about 12~13 bar and volume efficiency was reduced about 16%. The efficiency of volume and the work of compression were reduced on LIVC.

• 한국분무공학회지
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• 제27권2호
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• pp.101-108
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• 2022

Performance and emissions with different diesel injection methods were analyzed in a natural gas-diesel, dual-fuel engine under low-load conditions. Natural gas was supplied to intake port during the intake stoke to form a natural gas-air premixed mixture for all methods. Diesel was injected directly into the cylinder during the compression stroke in three ways: early injections, late injections, and a combination of early and late injections. The early injections had the highest thermal efficiency among the three methods owing to its highest combustion efficiency. The wide dispersion of diesel before the combustion initiation also allowed superior emissions characteristics.