• Title/Summary/Keyword: 5공 인젝터

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A Study on Relation of Needle-Nozzle Flow of Piezo-driven Injector by using Eulerian-Lagrangian Multi-phase Method (Eulerian-Lagrangian 다상 유동해석법에 의한 피에조인젝터의 니들-노즐유동 상관성 연구)

  • Lee, Jin-Wook;Min, Kyoung-Doug
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.108-114
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    • 2010
  • The injection nozzle of an electro-hydraulic injector is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the effects of needle movement in a piezo-driven injector on unsteady cavitating flows behavior inside nozzle were investigated by cavitation numerical model based on the Eulerian-Lagrangian approach. Aimed at simulating the 3-D two-phase flow behavior, the three dimensional geometry model along the central cross-section regarding of one injection hole with real design data of a piezo-driven diesel injector has been used to simulate the cavitating flows for injection time by at fully transient simulation with cavitation model. The cavitation model incorporates many of the fundamental physical processes assumed to take place in cavitating flows. The simulations performed were both fully transient and 'pseudo' steady state, even if under steady state boundary conditions. As this research results, we found that it could analyze the effect the pressure drop to the sudden acceleration of fuel, which is due to the fastest response of needle, on the degree of cavitation existed in piezo-driven injector nozzle.

Effect of Injection Conditions on the Spray Behaviors of the Multi-hole GDI Injector (분사 조건이 다공형 GDI 인젝터의 분무 거동에 미치는 영향)

  • Park, Jeong-Hwan;Park, Su-Han;Lee, Chang-Sik;Park, Sung-Wook
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.2
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    • pp.116-122
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    • 2012
  • The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fuel. In a constant volume chamber, the injected spray was visualized by the spray visualization system, which consisted of the high-speed camera, the metal-halide lamp, the injector control device, and the image analysis system with the image processing program. It was revealed that the injection quantity was mainly affected by the difference between the injection pressure and the ambient pressure. For low injection pressure conditions, the injection quantity was decreased by the increase of the ambient pressure, while it nearly maintained regardless of the ambient pressure at high injection pressure. According to the increase of the ambient pressure in the constant volume chamber, the spray development became slow, consequently, the spray tip penetration decreased, and the spray area increased. In additions, the circular cone area decreased, and the vortex area increased.

Comparison of Supersonic Jet Characteristics between Hydrogen and Helium injected by Small-cone-angle Pintle-type Hydrogen Injector (수소 및 헬륨을 이용한 작은 원추각 핀틀형 수소인젝터의 초음속 제트 특성 비교)

  • Gyuhan Bae;Juwan Lim;Jaehyun Lee;Seoksu Moon
    • Journal of ILASS-Korea
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    • v.29 no.2
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    • pp.83-90
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    • 2024
  • Understanding the fundamental characteristics of supersonic hydrogen jets is important for the optimization of combustion in hydrogen engines. Previous studies have used helium as a surrogate gas to characterize the hydrogen jet characteristics due to potential explosion risks of hydrogen. It was based on the similarity of hydrogen and helium jet structures in supersonic conditions that has been confirmed using hole-type injectors and large-cone-angle pintle-type injectors. However, the validity of using helium as a surrogate gas has not been examined for recent small-cone-angle pintle-type injectors applied to direct-injection hydrogen engines, which form a supersonic hollow cone near the nozzle and experience the jet collapse downstream. Differences in the physical properties of hydrogen and helium could alter the jet development characteristics that need to be investigated and understood. This study compares supersonic jet structures of hydrogen and helium injected by a small-cone-angle (50°) pintle-type hydrogen injector and discusses their differences and related mechanisms. Jet penetration length and dispersion angle are measured using the Schlieren imaging method under engine-like injection conditions. As a result, the penetration length of hydrogen and helium jets showed a slight difference of less than 5%, and the dispersion angle showed a maximum of 10% difference according to the injection condition.

Atomization Characteristics of Fuel Spray in Fuel Injector in Gasoline Direct-Injection Engine (가솔린 직분식 엔진 인젝터의 연료 분무 미립화 특성)

  • Lee, C.S.;Lee, K.H.;Choi, S.C.;Kwon, S.I.
    • Journal of ILASS-Korea
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    • v.4 no.2
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    • pp.33-39
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    • 1999
  • This paper presents the spray atomization characteristics of the high-pressure gasoline injector for the direct-injection gasoline engine. The gasoline sprays of the injector were minted into a pressurized spray chamber with a optical access at various ambient pressures. The atomization characteristics of fuel spray such as mean diameter, mean velocity of droplet were measured by the phase Doppler particle analyzer system. In order to investigate the effect of fuel injection pressure on the quantitative characteristics of spray, the global visualization and experiment of particle measurement in the fuel spray were investigated at 3, 5 and 7 MPa of injection pressure under different ambient pressure in the spray chamber. Based on the results of this work, the fuel injection pressure of fuel injector in gasoline direct-injection engine have influence upon distribution of the mean velocity and droplet size of fuel spray. Also, the influence of injection pressure on the velocity distribution at various measuring location were investigated.

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Effects of Particle Size and Injector Geometry on Particle Dynamics (입자크기와 노즐형상이 입자유동특성에 미치는 영향)

  • 전운학;김종철;황승식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.5
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    • pp.97-103
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    • 1998
  • The flow structure of particles for two different injectors has been investigated experimentally by means of a Phase Doppler Particle Analyzer(PDPA). Two injectors used in the present study are the pipe and contraction nozzle. Particles of 0.8${\mu}{\textrm}{m}$, 30${\mu}{\textrm}{m}$, 60 ${\mu}{\textrm}{m}$, and 100${\mu}{\textrm}{m}$ diameter were injected with a constant mass loading ratio of 0.01 and a Reynolds number of 13200. The initial mean velocity and turbulent intensity of particle are strongly influenced by the particle size and the injector geometry. The flow angles of particle at nozzle exit are sensitive to the particle size rather than the injector geometry.

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A Study on the Atomization and Combustion Characteristics of Air-assisted Injector in MPI Engine (MPI 엔진용 공기 보조 인젝터의 분무 미립화 및 연소 특성에 관한 연구)

  • 서영호;이창석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.52-58
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    • 1998
  • The spray characteristics of air-assisted fuel injection and its effects on the engine combustion was investigated in this study. The atomization characteristics of a Bosch fuel injector inserted into the air-assist adapter were measured using particle motion analysis system. Droplet size decreased with air supplied and fine spray with below $60\mu\textrm{m}$ of SMD was acquired under the conditions of air-assist pressure over 0.5bar. The lean combustion performance of a 1.8L DOHC engine equipped with air-assist adapters was tested on the dynamometer. When the assistant air pressure is 1.0bar, lean limit recorded the highest value, and CO, HC emissions were decreased at the pressure over 1.0bar.

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A study on the Velocity Distribution of the Liquid Sheet Formed by Two Impinging Jets at Low Velocities (저속 충돌제트에 의해 형성되는 액막의 속도 분포에 관한 연구)

  • Choo, Yeon-Jun;Kang, Bo-Seon
    • Journal of ILASS-Korea
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    • v.5 no.1
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    • pp.41-48
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    • 2000
  • In this research, the velocity distribution of the liquid sheet formed by two impinging jets at low velocities are measured using LDV. The spatial distribution of the sheet velocity as well as the effects of impinging anlge and jet velocity on the sheet velocity are examined. The sheet velocity is highest along the sheet axis and it decreases with the increase of the azimuthal angle. With the increase of the impinging angle, the average sheet velocity is decreased due to the increased impact momentum. The average sheet velocity is proportional to the jet velocity but it is always higher than the jet velocity. This result is against the fact that the sheet velocity can be assumed to be equal to the jet velocity in the previous researches.

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Macroscopic Breakup Characteristics of Water Gel Simulants with Triplet Impinging Spray Jet (젤 모사 추진제 삼중 충돌 분사 제트의 거시적 분열 특성 연구)

  • Hwang, Tae-Jin;Lee, In-Chul;Koo, Ja-Ye
    • 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.

Visualization of Gasoline Sprays Via a Simultaneous Inaging of Fluorescence and Scattering Lights (형광, 산란광 동시 촬열법을 이용한 가솔린 분무의 거동에 관한 연구)

  • 원영호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.6
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    • pp.167-174
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    • 1997
  • The penetration depth and the size distribution of the droplets of fuel sprays are important in the operation of spark-ignition MPI engines. A fluorescence/scattering image technique for droplet sizing was applied to measure th edroplet size distribution in non-evaporating gasoline sprays. The fluorescence and scattering lights were imaged simultaneously by the two-dimensional visualization system composed of a laser sheet, a doubling prism, optical filters, and a CCD camera. Quantitative droplet size distributions were extracted from evaluating the ratio of the two light densities. The mean droplet size measured by the fluorescence/scattering technique was compared with the result obtained by the enlarged photographs of droplets. The fluorescence/scattering image technique also gives the useful information of the characteristics of droplet impingement in a inclined wall.

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Development of Flow Rate Model of a Liquid Phase LPG Injector (액상 LPG 인젝터의 유량 모델 개발)

  • 조성우;민경덕
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.5
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    • pp.22-28
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    • 2003
  • Flash boiling mechanism in the injector interferes with fine fuel metering in a liquid phase LPG injection engine. This study presents a mathematical model to precisely predict an injection quantity. A calibration procedure of injection quantity, which is very prompt and precise in measuring, is developed using a gas analyzer. According to this procedure, injection quantity can be obtained under various fuel compositions, temperatures and injection pressures. The release pressure of liquid phase LPG is estimated based on these experimental data. Although the release pressure is much lower than the saturation pressure, it is linearly proportional to the saturation pressure.