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Kim, Byong-Kwon,Ra, Jin-Hong,Ann, Soo-Kil 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
Optically accessible D.I Diesel engine with a rectangular combustion chamber was constructed to visualize the behaviors of sprays and flames in the combustion chamber with the close conditions of pressure and temperature of the actual engine. The behaviors of sprays and flames in the combustion chamber in accordance with various operating conditions were photographed with high speed camera by both back illumination scattering method and schlieren method. With the photographs taken by these methods, the behaviors of the evaporating sprays and the spray droplets, ignition points, and the flame patterns were compared and analyzed with temporal spatial faction by image processor.
Diesel Spray-Wall Interation Model and Spray Characteristics of a High Pressure Injection System
Park, Kweonha,Choi, J. S.,Jeon, H. J. 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
This paper describes a new mathematical model for the calculation of a diesel spray impacting onto a wall, and its implementation in to a computational fluid dynamics computer code for the calculation of engine flows, then the model applies to get numerical results for the high pressure effects on spray characteristics in wide space or limited space with near walls. The discrete droplet model is used for the spray calculation. The gas phase is modelled m terms of the Eulerian equations. These equations are transformed into general non-orthogonal coordinates and solved in a finite volume manner. Lagrangian equations are used for the liquid phase. The sets of algebraic equations are solved by a non-iterative implicit solution scheme.
Measurement of Indicated Mean Effective Pressure
TSUCHIYA, Kazuo,AOKI, Mitsuhiko,Tetsuji, KOYAMA,KAWA, Tsunemichi,KAMIMOTO, Takeyuki 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
A convenient new type digital Pmi meter using a personal computer with A/D and PIO cards was developed. The Pmi meter takes an attention to low frequency harmonics in the range of 10-300 Hz in pressure wave form. It has advantage in the number of computations and accuracy as compared with a conventional method. The accuracy depends on the number of pressure data sampled per cycle, however if the sample numbers more than thirty-six for four cycle engines are selected, the error is kept approximately within 1.2%. It is accurate enough for practical usage. For monitoring Pmi, it is possible to use smaller sample numbers. The Pmi meter developed has possibility as onboard apparatus for engine control.
Technical Trends and Issues in Regard to Automotive Clean Energy Vehicles
KIM, YONG KIL 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
Reviewing technical development of automotive new clean energy vehicles such as Natural Gas Engine, methanol Engine and EV/Hybrid since 1960 years, for 21 century, I would like to describe the technical issues must be solved.
Analysis of Mixture Formation and Combustion Process in a DISC Engine
Yasuo, Moriyoshi 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
In this report, the author has, briefly introduced research summary on the stratified charge combustion system that has a possibility of simultaneous reduction of exhaust emissions and fuel' consumption rate. Firstly, the effect of spatial distribution of mixture stratification on combustion characteristics was investigated using a constant volume chamber. Secondly, the break-up process of fuel spray was examined to control the mixture formation process. Thirdly, turbulence and combustion modeling was discussed as a tool to clarify the physical phenomena. Finally, a model GDI engine was employed to evaluate a new concept.
Yu, Chul Ho,Noh, Seok Hong 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
The change of spray shape under different ambient pressure and the size distribution of fuel droplets from swirl Injector were investigated. And for the stratified mixture operation in the vicinity of spark plug , fuel distribution after impingement on piston in motoring engine was examined in the cases of two different injector positions. Also, the influence of intake port geometry and piston top shape on in cylinder air flow during intake to compression stroke was investigated. This paper concludes that , in tumble based combustion strategy , locating swirl injector at intake side of cylinder head and making counter rotating tumble increased in intake port geometry and conserved on bowel piston surface very effective for Stratified combustion of spark-ignited direct injection engine.
YUKIO, MATSUI,SHUJI, KIMURA 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
Nitrogen oxide (Nox) and particulate matter (PM) emissions of diesel vehicles are regarded as a source of air pollution, and there is a global trend to enforce more stringent regulations on these exhaust gas constituents in the early years of the-21st century. On the other hand, the excellent thermal efficiency of diesel engines is certainly a welcome attribute from the standpoints of conserving energy and curbing global warming. Recently, many research institutes around the world have been using high-efficiency direct-injection (DI) diesel engines to research emission control technologies. The authors have also been researching emission control technologies using a high-efficiency Di diesel engine. As a result of this work, we have developed a new combustion concept, called Modulated Kinetics (MK), that reduces NOx and smoke simultaneously through low-temperature combustion and premixed combustion, respectively This paper describes the combustion and emission characteristics obtained when this new combustion concept was applied to a single-cylinder engine and a multi-cylinder engine. It also shows the possibility of obtaining high-efficiency, ultra-clean internal combustion engines for the 21 st century.
Global Trends in Internal Combustion Engines
Takeyuki, Kamimoto 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
Global wanning, energy saving and local pollution issues demand more advanced propulsion systems for automobiles for the future. These demands are accelerating the development of new systems such as fuel-cell and hybrid vehicles. This article describes first the state-of-art of these new technologies and relevant factors such as fuel cost and customers needs, and then introduces several estimates on the time schedule of possible introduction of these technologies. The performances of the conventional piston engines are being significantly improved recently so as to be competent to these new systems. The current trends in internal combustion engines are also explained in the latter half of the article.
Two-Dimensional Imaging of Ignition Processes in a Transient Fuel Spray
Hidenori, Kosaka,Takeyuki, Kamimoto 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
To investigate the ignition processes in a diesel spray, the to-dimensional techniques of silicone oil particle scattering imaging (SSI) and laser induced fluorescence (LIF) were used. The sequential and two-dimensional images of SSI reveal that the first ignition occurs in the periphery of spray head vortices, not in spray tip. The fluorescent images of intermediate products which arc formed during the ignition reaction were taken by the LIF method with the laser sheet of the of the 3rd harmonics of ND:YAG laser. We conducted these visualization techniques and measured the chamber pressure under the same conditions. Then the ignition delay obtained by each technique was compared. This comparison showed that both the time when the first local heat release is. detected by SSI method and the time when the first fluorescence is by LIF method are nearly equal to the time when the total heat release due to ignition reaction exceeds the heat absorption of fuel evaporated.
BAE, Myung-whan,HA, Jeong-ho,IM, Gi-chang,CHO, Nam-in,JIN, Seong-gyu 경상대학교 공과대학 항공기계공학부 1999 WORKSHOP 자료집 Vol.1999 No.1
The effects of recirculated exhaust gas on the characteristics of NO_x and soot emissions under a wide range of engine loads are experimentally investigated using a four-stroke, four-cylinder, indirect injection, water-cooled marine diesel engine operating at two engine speeds. The aim of this study is to develop the EGR control system for NO_x and smt emissions simultaneously in diesel engines. The EGR system is used to reduce NO_x emissions. And a novel diesel soot removal device with a cylinder-type scrubber for the experiment system is specially designed and manufactured to reduce soot contents in the recirculated exhaust gas to the intake system of the engine. It is found that NO_x emissions decrease markedly, especially at higher loads, while soot emissions increase owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as the EGR rate is elevated.