• Title/Summary/Keyword: Injection Speed

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ANALYSIS OF IN-CYLINDER FUEL-AIR MIXTURE DISTRIBUTION IN A HEAVY DUTY CNG ENGINE

  • Lee, Seok-Y.;Huh, Kang-Y.;Kim, Y.M.;Lee, J.H.
    • International Journal of Automotive Technology
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    • v.2 no.3
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    • pp.93-101
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    • 2001
  • Distribution of fuel-air mixture has a strong influence on performance and emissions of a compressed natural gas (CNG) engine. In this paper, parametric study is performed by KIVA-3V to investigate fuel-air mixture with respect to injection timing, cycle equivalence ratio and engine speed. With open-valve injection intensive mixing during intake and compression stroke results in relatively homogeneous mixture in the cylinder. Sequential induction of fuel-air mixture and fresh air results in stratification in the cylinder among the test cases at closed-valve injection. There is close similarity in the calculated distributions of the mixture in the cylinder with different cycle equivalence ratios and engine speeds. The results are compared against pressure traces and flame images obtained in a single cylinder engine converted from a 11L six-cylinder heavy duty diesel engine.

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A Study on the Dynamic Characteristics of a Turbocharged Diesel Engine (터보 과급 디젤 기관의 동특성에 관한 연구)

  • Choi, N.J.;Lee, C.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.1
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    • pp.143-154
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    • 1995
  • This study investigates the response characteristics of a four-cylinder four-stroke turbocharged diesel engine by using computer simulation and experiments when a rapid acceleration is applied to the fuelpump rack. In the theoretical analysis, linearization method is used to avoid the difficulty on the complex nonlinear functions. Comppressor exit pressure, pressure and temperature of turbine inlet, and turbocharger speed are chosen as the independent variables of transfer functions which represent the dynamic characteristics of the turbocharger system, and expressed as the functions with respect to the time. Experiments on the same eigine system are also carried out to prove the validity of theoretical study. Further, this study carried an experiment for improving transient response performance by injecting air into the inlet manifold under the rapid accelerating conditions. The effects of air injection on the response performances are also represented at varying conditions such as injection pressure, injection period, accelerating rate, accelerating time, engine speed and load.

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Spray Characteristics of the Rotating Fuel Nozzle with Orifice Geometry (회전연료노즐 형상변경에 따른 분무특성)

  • Jang, Seong-Ho;Choi, Hyun-Kyung;Lee, Dong-Hun;You, Gyung-Won;Choi, Seong-Man
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.05a
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    • pp.240-243
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    • 2008
  • An experimental study was conducted to understand spray characteristics of rotating fuel nozzle by using high speed rotational system. The experimental apparatus consist of a fuel injection system, high speed rotational system, and acrylic case. The test is performed with several diameters and number of injection orifices. Spray characteristics such as droplet size and velocity are measured by PDPA(Phase Doppler Particle Analyzer). From the test results, we could understand the spray characteristics of rotating fuel nozzle with orifice number and diameter.

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Process Control for the Synthesis of Ultrafine Si3N4-SiC Powders by the Hybrid Plasma Processing (Hybrid Plasma Processing에 의한 Si3N4-SiC계 미립자의 합성과정 제어)

  • ;吉田禮
    • Journal of the Korean Ceramic Society
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    • v.29 no.9
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    • pp.681-688
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    • 1992
  • Ultrafine Si3N4 and Si3N4+SiC mixed powders were synthesized through thermal plasma chemical vapor deposition(CVD) using a hybrid plasma, which was characterized by the supersposition of a radio-frequency plasma and arc jet. The reactant SiCl4 was injected into an arc jet and completely decomposed in a hybrid plasma, and the second reactant CH4 and/or NH3 mixed with H2 were injected into the tail flame through double stage ring slits. In the case of ultrafine Si3N4 powder synthesis, reaction efficiency increased significantly by double stage injection compared to single stage one, although crystallizing behaviors depended upon injection speed of reactive quenching gas (NH3+N2) and injection method. For the preparation of Si2N4+SiC mixed powders, N/C composition ratio could be controlled by regulating the injection speed of NH3 and/or CH4 reactant and H2 quenching gas mixtures as well as by adjusting the reaction space.

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Spray Characteristics of the Rotating Fuel Injection System (회전연료 분사시스템의 분무특성)

  • Lee, D.H.;Park, J.B.;Choi, S.M.
    • Journal of ILASS-Korea
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    • v.11 no.2
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    • pp.81-88
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    • 2006
  • The spray characteristics of the rotating fuel injection system were investigated. The special test rig was devised to get the spatial and momentary droplet information. This experimental apparatus consists of a high-speed motor, a shaft, a rotating fuel nozzle and an acrylic case. Spray droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and instantaneous velocity field was measured by 1'IV (Particle Image Velocimetry) system. At the same time, spray visualization was performed by using ND-YAG laser-based flash photography. From these two different laser diagnostic techniques, we could get spatial and instantaneous spray information fur rotating fuel injection system. The results presented in this paper indicate that spray characteristics such as droplet size, velocity and spray pattern were strongly influenced by rotational speed.

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Effects of the Intake Valve Timing and the Injection Timing for a Miller Cycle Engine

  • Han, Sung-Bin;Chang, Yong-Hoon;Choi, Gyeung-Ho;Chung, Yon-Jong;Poompipatpong, Chedthawut;Koetniyom, Saiprasit
    • Journal of Energy Engineering
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    • v.19 no.1
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    • pp.32-38
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    • 2010
  • The objective of the research was to study the effects a Miller cycle. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. Miller Cycle without supercharging can increase brake thermal efficiency 1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency.

An Experimental Study of the Micro Turbojet Engine Fuel Injection System

  • Choi, Hyun-Kyung;Choi, Seong-Man;Lee, Dong-Hun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.1-5
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    • 2008
  • An experimental study was performed to develop the rotational fuel injection system of the micro turbojet engine. In this system, fuel is sprayed by centrifugal forces of engine shaft. The test rig was designed and manufactured to get droplet information on combustion space. This experimental apparatus consist of a high speed rotational device(Air-Spindle), fuel feeder, rotational fuel injector and acrylic case. To understand spray characteristics, spray droplet size, velocity and distribution were measured by PDPA (Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the length of liquid column from injection orifice is controlled by the rotational speeds and Sauter Mean Diameter(SMD) is decreased with rotational speed. Also, Sauter Mean Diameter is increased as increasing mass flow rate at same rotational speeds.

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Effect of Injection Parameters on Combustion and Exhaust Emission Characteristics in a Small Common-rail Diesel Engine (분사 조건의 변화가 소형 커먼레일 디젤 엔진의 연소 및 배기 특성에 미치는 영향)

  • Kim, Myung-Yoon;Lee, Doo-Jin;Roh, Hyun-Gu;Lee, Je-Hyung;Lee, Chang-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.9-15
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    • 2004
  • The characteristics of combustion and emissions were investigated in a single cylinder DI diesel engine equipped with a common rail injection system. This study presents an experimental study of the effect of engine speed, injection timing, injection pressure and pilot injection timing on the combustion and exhaust emissions. The engine speeds were 1000 and 2000rpm and the corresponding injection pressures were 50 and 100MPa. Experimental results show that NOx emissions decrease with retarded injection timing, while HC and CO emissions increases. Higher injection pressure increases NOx with lower soot emissions. For the case with the pilot injection prior to main injection, the ignition delay is shortened and the premixed combustion ratio decreases. Also NOx and soot emissions are decreased with increase of pilot injection advance.

Fabrication Process of Aluminum Bipolar Plate for Fuel Cell using Vacuum Die Casting (진공 다이캐스팅 공법을 이용한 연료전지용 알루미늄 분리판의 제조 공정)

  • Jin, Chul-Kyu;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.31 no.2
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    • pp.71-78
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    • 2011
  • This study aims to investigate the formability of bipolar plates for fuel cell fabricated by vacuum die casting of ALDC 6. Cavity shape of mold is thin walled plate (size: $200mm{\times}200mm{\times}0.8mm$) with a serpentine channel (active area: $50mm{\times}50mm$). Before bipolar plate was made by HPDC, computational filling behavior and solidification was performed by MAGMA soft. The final mold design for location and direction of channel was determined by computational simulation. Also, according to injection speed conditions, simulation result was compared to actual die casting experimental result. When vacuum pressure, injection speed of low and high region is 350 mbar, 0.3 m/s and 2.5 m/s respectively, products had few casting defects. On the other hand, at the same as injection speed, without vacuum pressure, products had many casting defects between end of the channel and overflow.

Experimental Research of Multi-Stage Axial Compressor Stability Enhancement by Air Injection (다단 축류압축기의 안정성 개선을 위한 실험적 연구)

  • Lim, Young-Cheon;Lim, Hyung-Soo;Song, Seung-Jin;Kang, Shin-Hyoung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.378-381
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    • 2009
  • A rotating stall, an instable phenomenon of compressor, brings about reducing the pressure rise, the efficiency of compressor and a mechanical demage. In order to improve instability and extend operating range, it was performed that a stability enhancement experiment applying air injection method at the 4-stage low-speed axial compressor. The coanda nozzle was used to inject air in axial direction at rotor tip and 8 injectors were set up at regular interval at the upstream of 1st stage rotor. At 80% speed, injectors were worked before rotating stall happened. As injecting the 5.4% air of mode inception flow rate, the stability of compressor operation enhanced about 4%.

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