• Title/Summary/Keyword: Spray Internal Structure

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Spray Structures and Vaporizing Characteristics of a GDI Fuel Spray

  • Park, Dong-Seok;Park, Gyung-Min;Kim, Duck-Jool
    • Journal of Mechanical Science and Technology
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    • v.16 no.7
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    • pp.999-1008
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    • 2002
  • The spray structures and distribution characteristics of liquid and vapor phases in non-evaporating and evaporating Gasoline Direct Injection (GDI) fuel sprays were investigated using Laser Induced Exciplex Fluorescence (LIEF) technique. Dopants were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to study internal structure of the spray, droplet size and velocity under non-evaporating condition were measured by Phase Doppler Anemometry (PDA). Liquid and vapor phases were visualized at different moments after the start of injection. Experimental results showed that the spray could be divided into two regions by the fluorescence intensity of liquid phase: cone and mixing regions. Moreover, vortex flow of vapor phase was found in the mixing region. About 5㎛ diameter droplets were mostly distributed in the vortex flow region. Higher concentration of vapor phase due to vaporization of these droplets was distributed in this region. Particularly, higher concentration of vapor phase and lower one were balanced within the measurement area at 2ms after the start of injection.

Comparison of Overall Characteristics between an Air-Assisited Fuel Injector and a High-Pressure Swirl Injector-Part I: Flow rate and Macroscopic Spray Characteristics (공기보조 분사기와 고압 선회식 분사기의 특성 비교- Part 1:유량 및 거시적 분무특성)

  • 장창수;최상민
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.20-27
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    • 2000
  • Characteristics of two favorite injection tools for gasoline direct injection application were compared. An air-assisted fuel injector (AAFI) and a high-pressure swirl injector (HPSI) were designed and fabricated for prototype development, and the characterization strategies and processes for both injection tool have been arranged in parallel. Characterization works were carried out mainly through measurements, and in some cases, computational fluid dynamic analysis was utilized. In this paper, overall characteristics defined as flow rate, spray pattern, penetration, internal spray structure and drop size distribution, was discussed. The AAFI was found to be advantageous in flexibility of fuel flow rate, and the HPSI in stability and precision. Spray shape factor was introduced to describe the development of intermittent sprays from both injectors. Axial penetration appeared to be almost linear in the case of the AAFI while its speed continuously decreased with time in the HPSI.

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A Study on Nozzle Flow and Spray Characteristics of Piezo Injector for Next Generation High Response Injection (차세대 고응답 분사용 피에조 인젝터의 노즐유동 및 분무특성에 관한 연구)

  • Lee Jin-Wook;Min Kyoung-Doug
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.6 s.249
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    • pp.553-559
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    • 2006
  • Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(volume of fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response In a piezo-driven injector were reflected to spray development in agreement with the experimental spray images.

The Effect of Flux on the Preparation of Spherical Fine Phosphor Particles (미분의 구형 형광체 제초에 있어서 융제의 영향)

  • 노현숙;강윤찬;서대종
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.570-573
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    • 1999
  • High brightness (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu Phosphor Particles were directly Prepared in the spray Pyrolysis by adding flux materials such as LiCl and HBO$_3$. The (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu particles prepared from solution with flux material had higher PL (photoluminescence) intensities than those prepared from solution without flux. In the spray pyrolysis, the flux acts as promoter of the growth of crystallite and activation of doping material as in the solid state reaction method. Additionally, the flux improved PL intensity of (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu phosphor particles by densifying the internal structure and eliminating the defect existing inside and surface of (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu phosphor particles.r particles.

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Surface Characteristic of Graphene Coated Stainless Steel for PEMFC Bipolar Plate (그래핀이 코팅된 스테인리스강의 고분자전해질 연료전지 분리판 적용을 위한 표면 특성)

  • Lee, Su-Hyung;Kim, Jung-Soo;Kang, Nam-Hyun;Jo, Hyung-Ho;Nam, Dae-Guen
    • Journal of the Korean institute of surface engineering
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    • v.44 no.5
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    • pp.226-231
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    • 2011
  • Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.

Comparison of Overall Characteristics between an Air-Assisted Fuel Injector and a High-Pressure Swirl Injector- Part II: Microscopic Spray Characteristics (공기보조 분사기와 고압 선회식 분사기의 특성 비교 - Part II: 미시적 분무특성)

  • 장창수;최상민
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.28-35
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    • 2000
  • As a second part of the comparison study, microscopic features of an air-assisted fuel injector(AAFI) and a high-pressure swirl injector (HPSI) were characterized. They consist of the internal spray structure in terms of fuel mass and drop diameter, the overall atomization performance with respect to operating parameters and the drop size distribution. Large droplets are concentrated in around the head part of a spray field of the HPSI, while in the case of the AAFI, they were distributed in the tail part. Although the AAFI showed the better atomization performance, the feasible ranges of operating parameters such as injection and ambient pressure were found to be wider in the HPSI. Drop size distribution of the AAFI sprays was more dispersed than that of the HPSI. Drop size distribution of the AAFI sprays was more dispersed than that of the HPSI. However, at the well-atomized condition, it appeared to be very uniform.

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Correlations of Internal Nozzle Flow in Circular and Elliptical Nozzles with External Flow (원형 및 타원형 노즐 내부유동과 외부유동의 상관관계)

  • Ku, Kun-Woo;Hong, Jung-Goo;Park, Cheol-Won;Lee, Choong-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.3
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    • pp.325-333
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    • 2012
  • An experimental study was carried out to determine the correlation between the internal flow in a circular nozzle and elliptical nozzles with the external flow. The flow rate, spray angle and drop size were measured under various conditions of the injection pressure. Numerical simulations were attempted to investigate the internal flow structure in the elliptical nozzles, because the experimental study was limited in its measurements of flow velocity and pressure distributions in the relatively small orifice. In the case of the elliptical nozzles, the disintegration characteristics of the liquid jet were significantly different from those of the circular nozzle. Surface breakup was observed at the jet issued from the elliptical nozzles with injection pressure. This is due to the internal flow structure, which is reattached to the orifice wall at the minor axis plane of the elliptical nozzle, unlike that observed with the circular nozzle.

Experimental Study on Evaluation of Bond Strength after Ozone Treatment and Ozone Resistance of Concrete Metal Spray Coating for Advanced Water Treatment (고도정수처리용 콘크리트 금속용사 피막의 내오존성 및 오존처리 후 부착강도 평가에 관한 실험적 연구)

  • Park, Jin-Ho;Jang, Hyun-O;Lee, Han-Seung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.68-75
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    • 2018
  • The introduction of advanced water treatment facilities has increased as the conventional purification method cannot remove the substance clearly. However, the internal waterproofing and Anticorrosion materials of the advanced water treatment facility using ozone deteriorate due to the oxidation power of ozone and affects the concrete, which causes a decrease in durability. This study is to evaluate the ozone resistance according to the type of spray metal and the surface treatment method of the coating, and the bond strength after ozone treatment in order to develope a finishing method to prevent deterioration of concrete structure of water treatment facility using metal spraying method as a way to construct metal panel with excellent ozone resistance and chemical resistance by an easier way than the previous. The Experimental results show that spray metal Ti has superior ozone resistance even after spraying. It is considered to be the most suitable method for ozone resistance and bond performance by finishing using Teflon sealing as surface treatment method.

Atomization Characteristics of 2-Phase Atomizer with the change of Mixing Chamber Structure (혼합실 구조 변경에 의한 2상 노즐의 미립화 특성)

  • Ha, M.H.;Kim, K.C.;NamKung, J.H.;Lee, S.G.;Rho, B.J.;Kang, S.J.
    • Proceedings of the KSME Conference
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    • 2001.11b
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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.

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An Elementary Study on the Combustion Mechanism of Levitated Droplet Clusters by Ultrasonic Wave (초음파를 이용한 부상유적군의 연소기구에 관한 기초연구)

  • Jung, Jin-Do;Kim, Seung-Mo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.8
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    • pp.1191-1199
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    • 2003
  • This paper describes to observe the combustion process of only one droplet cluster. In this study, liquid fuel was atomized by ultrasonic wave to form an acoustically levitated droplet cluster. In order to elucidate the detailed structure of burning process of the droplet cluster, laser tomography method was applied. Time-series planar images of fuel droplets were processed and diameter of the each droplet was calculated based on the Mie-scattering theory. Using these data, the modified droplet group combustion number was estimated in time-series. As the result, when the internal droplet group combustion occur, the modified group combustion number dose not decrease monotonically, but show a tow-staged decreasing process. In all case of combustion process, combustion reactions were measured two types that combustion speed was fast and slow. It was casued by difference of concentration degree and droplet size distribution.