• Journal of ILASS-Korea
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• v.5 no.2
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• pp.68-74
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• 2000

A this experimental study is executed to analyze spray characteristics for air-shrouded injector and 4hole 2spray type injector used in a gasoline engine. Since spray parameters including spray penetration and angle, SMD, and atomization characteristics are very important to increase the engine performance, the image processing algorithm for measuring the non-spherical spray diameter is developed. Spray characteristics of the air-shrouded injector(2hole 2spray) and 4hole-2spray injector are analyzed respectively by this digital image processing method. Effective spray characteristics to injectors is derived from this experimentation and obtained the design guide for gasoline injector.

• Journal of ILASS-Korea
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• v.15 no.3
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• pp.109-114
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• 2010

The implementation of gelled propellants systems offers high performance, energy management of liquid propulsion, storability, and high density impulse of solid propulsion. The present study focused on the macroscopic spray characteristics of liquid sheets formed by triplet impinging jets of non-Newtonian liquids which are mixed by Carbopol 941 0.5%wt. The results are compared to experiments conducted on spray images which formed by triplet impinging jets concerning with airassist effect at center orifice. When gel propellants are injected by doublet impinging jets at low pressure and high pressure, closed rim pattern shape appeared by polymeric effect from molecular force and showed inactive atomization characteristics, because of extensional viscosity related by restriction of atomization process and breakup time delay of turbulence transition. As increasing mass flow rate of the air(increasing GAR), spray breakup level is also increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.948-951
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• 2000

This paper presents the analytical and experimental methodology for the prediction of aerosol concentration and size distribution due to cutting fluid atomization mechanism in turnining operation. The established analytical model which is based on atomization theory analyzes the cutting fluid motion and aerosol generation in machining process. The impinging and evaporation experiments were performed to know the particle size and evaporation rate of cutting fluid. The predictive models can be used as a basis for environmental impact analysis on the shop floor. It can be also facilitate the optimization of cutting fluid usage in achieving a balanced consideration of productivity and environmental consciousness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.545-552
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• 2004

The purpose of this study is to improve the prediction ability of the atomization and vaporization processes of GDI spray. Several models have been introduced and compared. The atomization process was modeled using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. The vaporization process was modeled using Spalding model and Abramzon ＆ Sirignano model. Exciplex fluorescence method was used for comparing calculated with experimental results. The experiment and computation were performed at the ambient pressure of 0.1 MPa, 0.5 MPa and 1.0 MPa and the ambient temperature of 293k and 473k. Comparison of calculated and experimental spray characteristics was carried out and the calculated results of GDI spray showed good agreement with experimental results.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.466-471
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• 2003

The purpose of this study is to obtain the accurate prediction for the atomization and vaporization processes of GDI spray. Atomization process is modeled using hybrid model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. Vaporization process is modeled using Spalding model and Abramzon & Sirignano model. To obtain the experimental results for comparing with calculated results, the cross-sectional images of liquid and vapor phases and SMD distribution were acquired by exciplex fluorescence method and Phase Doppler Analyzer respectively. The experiment and computation was performed at the ambient pressure of 0.1 MPa, 0.5 MPa, 1.0 MPa and the ambient temperature of 293K, 473K. The calculated results by modified KIVA-II code show good agreement with experimental results.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.869-874
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• 2003

The atomization characteristics were investigated through the influence of the change of GLR and the change of working fluid on droplet size distribution and mean diameter of drop produced by effervescent atomizer. For simultaneous injection of water and high viscous waste vegetable oil, effervescent atomizer with two aerator tubes was specially designed. From the experimental results, regardless of mass fraction of vegetable oil in working fluids, it is expected that effervescent atomizer will exhibit excellent atomization performance at the high GLR conditions.

• Journal of ILASS-Korea
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• v.14 no.3
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• pp.117-121
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• 2009

Biodiesel fuel has different spray patterns, because viscosity and surface tension of biodiesel fuel are higher than that of diesel fuel. The diesel combustion is strongly controlled by the fuel spray behavior in combustion chamber. So, it was needed to understand the spay characteristics of non-esterification biodiesel fuel. In this study, the spray characteristics of non-esterification biodiesel fuel was investigated to confirm of an effect of WDP. The characteristics of fuel atomization was analyzed with SMD and span factor through laser diffraction particle analyzer (LDPA), and the process of spray injection was visualized through the visualization system composed of a halogen lamp and high speed camera. It was found that injection delay time and SMD of blended fuel with WDP get shoter and smaller than that of non-esterification biodiesel fuel.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.46-47
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• 2004

The microstructure and mechanical properties of the hypereutectic prealloyed Al-Si powders prepared by the gas atomization process were described in this paper. With increasing the gas pressure of the atomization, the average powder size was decreased from about $145{\mu}m\;to\;80{\mu}m$. The primary eutectic Si particles were uniformly distributed in the Al matrix and their size varied in the range of $8-10{\mu}m$. The high densified specimens with above 96% of the theoretical density were fabricated the hot pressing process. The UTS mechanical properties of VN1 specimens were much higher than that of conventional hypoeutectic Al-Si alloys.

• Journal of ILASS-Korea
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• v.7 no.3
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• pp.1-6
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• 2002

In this study numerical and experimental study on the spray atomization characteristics of a GDI injector is performed. To carry out numerical analysis, four hybrid models that are composed of conical sheet disintegration model, LISA model, DDB model, and RT model are used. The experimental results to evaluate the prediction accuracy of hybrid models are obtained by using phase Doppler particle analyzer and spray visualization system. It is shown that the prediction accuracy of hybrid model concerning spray developing process and spray tip penetration is good for all hybrid models, but the hybrid breakup models show different prediction of accuracy in the case of local radial SMD distribution.

• Journal of ILASS-Korea
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• v.4 no.3
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• pp.8-14
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• 1999

The characteristics of the breakup process in supercritical spray is investigated during the injection of supercritical sulfur hexafluoride into dissimilar gases at supercritical pressures and subcritical temperature of the injected fluid. The visualization techniques used are backlighting and shadowgraph methods. The spray angles are measured and the breakup and mixing process are observed at near and supercritical conditions. The results show that spray angles are decreased with the in..ease of the ratio of density $(\frac{\rho_f}{\rho_g})$. At the supercritical temperature, the spray angles in atomization region are kept nearly constant such as the typical spray angle in gas injection. The mixing process is changed radically at the temperature where $\frac{d\rho}{dT}=\frac{1}{2}[\frac{d\rho}{dT}]_{max}$ at given pressure.