• 한국분무공학회지
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• 제15권2호
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• pp.74-82
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• 2010

In order to understand the behavior of transient gaseous injection used in an LPG (Liquefied Petroleum Gas) engine, turbulent incompressible transient jets with butane and propane were measured and analyzed at pressures of 1.5 bar and 2.0 bar with injector diameters of 3 mm and 5 mm. Mie-scattering method with a tracer was used, and images were processed to investigate the behavior of butane and propane jets. Distances from the nozzle to transition region were measured as $L_e/d_{inj}$=4.35~19.4, where $L_e$ and $d_{inj}$ indicate respectively a distance from nozzle to transition point and nozzle diameter. Slits and tubes around jet at near-field were introduced to measure the effect of entrainment and the diameter of jet, which revealed that the entrainment of surrounding air is significant for developing jet diameter. When the entrainment is restricted, the behavior of jet became deviating from the baseline. It was found that the virtual origin located outside of a nozzle towards jet tip within the conditions of this work, and its location was estimated as $x_o/d_{inj}$=0.56~7.25, where $x_o$ is a distance from nozzle to virtual origin.

• 한국분무공학회지
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• 제23권3호
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• pp.128-135
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• 2018

In this study, the following conclusions could be obtained from the analysis of emissions contribution rates and features for contaminated emissions by 13,456 gasoline vehicles passed in the vehicle load test (ASM-idle) under the inspection year 2013 to 2017. It was confirmed that the contamination of the CO, HC, NOx by the displacement is reduced on over 3L engine. As a result of comparing the exhaust gas in the low speed idle mode and the AS2525 mode, the exhaust gas in the low speed idle mode was measured high. It is estimated that if ISG function is applied, emissions from idle condition will be reduced. NOx emissions were reduced when the engine power was above 200HP. It has been confirmed that the amount of exhaust emissions are significantly reduced for vehicles manufactured after 2004. As a result of analyzing the exhaust gas according to the season, it is judged that there is a correlation between HC and NOx according to the ambient temperature. The concentration of exhaust emission in vehicles with high accumulated distance increases, which is considered to be the result of aging of the vehicle.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.341-346
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• 2011

To study the effects of salinity-sodicity on bacterial population and enzyme activities, soil samples were collected from the Bay of Yellow Sea, Incheon, South Korea. In the soils nearest to the coastline, pH, electrical conductivity ($EC_e$), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were greater than the criteria of saline-sodic soil, and soils collected from sites 1.5-2 km away from the coastline were not substantially affected by the intrusion and spray of seawater. Halotolerant bacteria showed similar trends, whereas non-tolerant bacteria and enzymatic activities had opposite trends. Significant positive correlations were found between EC, exchangeable $Na^+$, and pH with SAR and ESP. In contrast, $EC_e$, SAR, ESP, and exchangeable $Na^+$ exhibited significant negative correlations with bacterial populations and enzyme activities. The results of this study indicate that the soil chemical variables related with salinity-sodicity are significantly related with the sampling distance from the coastline and are the key stress factors, which greatly affect microbial and biochemical properties.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.59-63
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• 2006

횡단류 아음속유동장에서 연료의 수직 분사시 나타나는 액적영역의 액적들을 직접사진촬영으로 측정하고 PLLIF 실험을 통하여 얻은 강도 값으로 SMD분포를 측정하였다. 본 연구의 목적은 정상유동에서의 액적들의 크기 및 분포를 관찰하고, 캐비테이션 및 수력튀김 현상에 대한 액적들의 차이를 확인하는 것이다. 실험을 통하여 정상유동의 액적들은 분사차압, 공기의 유속, 침투거리, 인젝터 지름에 대한 하류방향 거리비(x/d)에 의하여 결정되며, 캐비테이션에 의한 난류강도, 유효지름에 따라 차이가 있음을 확인하였다.

• 한국분무공학회지
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• 제18권3호
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• pp.155-160
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• 2013

Worldwide harmonized light-duty vehicle test procedure (WLTP) for emission certification has been developed in WP.29 forum in UN ECE since 2007. The test procedure is expected to be applied to Korean light-duty diesel vehicles at the same time of adoption in Europe. The air pollutant emissions from light-duty vehicles have been regulated with weight per distance travelled which means the driving cycles can affect the results. The six Euro-5 light-duty diesel vehicles including sedan, SUV and truck have been tested with WLTP, NEDC which is used for emission certification for light-duty diesel vehicles, and CVS-75 to estimate how much particle number emission can be affected by different driving cycles. The averaged particle number emissions have not shown statistically meaningful difference. The maximum particle number emission have been found in Low speed phase of WLTP which is mainly caused by cooled engine conditions. The amount of particle number emission in cooled engine condition is much different as test vehicles. It means different technical solution is required in this aspect to cope with WLTP driving cycle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.699-704
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• 2001

The purpose of this study is to present the atomization characteristics of 2-phase internal mixing nozzle. The obtained results are considered as the essential information of understanding the spray characteristics from the nozzle exit of an aerated nozzle. In this study, SMD and AMD are mainly measured at the distance of Z=10, 20, 50, 80, 120 and 170mm from the nozzle tip. The liquid flow rate was kept at 1.8g/s and the air feeding pressure was changed from 10kpa to 100kpa increasingly. The analysis of the acquired data was performed by 2-D PDPA system and in order to get the realibility, the number of data used in calculating the SMD & AMD were 10,000 samples.

• 한국분무공학회지
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• 제8권4호
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• pp.9-16
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• 2003

The Purpose of this study is to investigate the relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames. And simultaneous CH and OH PLIF(Planar Laser Induced Fluorescence) measurement has been also conducted for lean premixed flame as well as for laminar flames. Numerical simulations are conducted for laminar premixed flames and turbulent ones by using PREMIX in CHEMKIN and two dimensional DNS code with GRI mechanism version 2.11, respectively. In the case of laminar premixed flame, the distance between the peak of heat release rate and that of CH concentration is under $91{\mu}m$ for all equivalence ratio calculated in present work. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements in the laminar premixed flame burner, CH fluorescence intensity as a function of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism. Simultaneous CH and OH PLIF measurement gave us useful information of instantaneous reaction zone. In addition, CH fluorescence can be measured even for lean conditions where CH mole fraction significantly decreases compared with that of stoichiometric condition. It was found that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the engine combustion.

• 대한기계학회논문집B
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• 제21권5호
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• pp.691-699
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• 1997

The effects of concave hemispherical surface curvature on the local heat transfer from a turbulent round impinging jet were experimentally investigated. The liquid crystal transient method was used for these measurements. This method, which is a variation on the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystals for the measurement of the surface temperature. The Reynolds number ranges from Re=11,000 to 50,000, the nozzle-to- surface distance from L/d=2 to 10, and the surface curvature from D/d=6 to 12.The present results are also compared to those for the flat plate case. In the experiment, the local Nusselt numbers tend to increase in all regions with an increasing surface curvature. The maximum Nusselt number for all Reynolds numbers occurred at L/d .ident. 6 and a second maximum in the Nusselt number occurred at R/d .ident. 2 for both Re=23,000 and Re=50,000 in the case of L/d=2 and for Re=50,000 only in the case of L/d=4. Meanwhile, as the surface curvature increases, the value of the secondary maximum Nusselt number decreases. All the other cases exhibit monotonically decreasing values of the Nusselt number along the curved surface. The stagnation point Nusselt numbers are well correlated with Re, L/d, and D/d.

• 한국분무공학회지
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• 제19권2호
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• pp.75-81
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• 2014

Swirl flow in the gun type burner has a decisive effect on the stabilization of the flame, improvement of the combustion efficiency, and also a reduction of NOx. This swirl flow is created by the spinner which is inside the airtube that guide the combustion air. Gun type burner has generally the inner devices composed nozzle adapter, spark gap ignitor, and spinner. These inner components change the air flow behavior passing through air tube. Meanwhile, turbulent characteristics of this air flow are important to understand the combustion phenomena in the gun type burner, because the mixture of fuel and air are depended on. However, nearly all of the studies have been analyzed the turbulent flow of simplified combustion formation without the inner devices. So, this study conducted the measurement using by hot-wire anemometer and analyzed turbulent flow characteristics of the swirl flow discharged from the air tube with inner devices. Turbulence characteristics come up in this study were turbulence intensity, kinetic energy and shear stress of the air flow with the change of the distance of axial direction from the exit of the air tube.

• 에너지공학
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• 제13권4호
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• pp.235-241
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• 2004

본 연구는 초음파 개질 바이오 디젤유의 점도와 표면장력에 대한 연료의 물리적 특성, 분무 미립화 특성에 관한 심층적이고 체계적인 연구에 중점을 두었다. 이를 규명하기 위하여 초음파 재질 연료와 개질 되지 않은 연료의 상대 비교 분석을 통한 연료특성과 연료분사펌프의 회전수 및 노즐선단 거리변화에 의한 입경측정의 상관성을 정립하였다.