• Proceedings of the KSME Conference
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• 2000.04b
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• pp.899-905
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• 2000

The characteristics of air flow and engine performance with swirl ratio variance of intake port In a turbocharged DI diesel engine was studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer and NOx, smoke were measured by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. And as the swirl ratio is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.86-96
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• 2000

This study is to consider that the helical intake port flow and fuel injection system have effects on the characteristics of engine performance and emissions in a turbocharged DI diesel engine of the displacement 9.4L. The swirl ratio for ports was modified by hand-working and measured by impulse torque swirl meter, For the effects on performance and emission, the brake torque, BSFC were measured by engine dynamometer and NOx, smoke were by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased, And as the swirl is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by the following applied parameter; the swirl ratio is 2.43, injection timing is BTDC $13^{\circ}$CA and compression is 15.5.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.1-13
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• 1993

The three-dimensional numerical analysis for in-cylinder flow of four-valve engine without intake port has been successfully computed. These computations have been performed using technique of the general coordinate transformation based on the finite-volume method and body-fitted non-orthogenal grids using staggered control volume and covariant variable as dependent one. Computations are started at intake valve opening and are carried through top-dead-center of compression. A k-$\varepsilon$model is used to represent turbulent transport of momentum. The principal study is the evolution of interaction between mean flow and turbulence and of the role of swirl and tumble in generating near TDC turbulence. Results for three different inlet flow configuration are presented. From these results, complex flow pattern may be effective for promoting combustion in spark-ignition engines and kinetic energy of mean flow near TDC is well converted into turbulent kinetic energy.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.662-670
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• 1999

A numerical prediction was performed to clarify the air motion in the cylinder of an axisymmet-ric four-stroke reciprocating engine at its intake and compression stage. A scheme of finite volume method is used for the calculation. Modified $k-{\varepsilon}$ turbulence model is adopted and wall function is applied to the grids near the wall. The predicted mean velocity and rms velocity profiles showed a reasonable agreement with an available experimental data at its intake and compression stage. The predicted in-cylinder flow fields show that a strong turbulent twin vortex structure is pro-duced during induction but it commences to decay rapidly around inlet valve closure. The mean velocity continues to fall to a low level during compression but the turbulence intensity attains an approximate constant level.

• Journal of Biosystems Engineering
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• v.28 no.4
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• pp.285-294
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• 2003

This study was carried out to propose a new-concept internal combustion engine which has great potential advantages to the conventional engines. Proposed new-concept engine is a kind of rotary engine. A rotor is rotating concentrically in a cylinder which is divided into two partitioning valves, and it makes four compartments in the cylinder. The volumes of each of four compartments are changing continuously with the rotor movement and performs the functions of intake, compression. expansion and exhaust simultaneously. Expected thermal efficiency for the real cycle is 26 percent at conditions of 1,000 rpm and compression ratio of 8.0, which is 3 to 4 percent higher than that of the conventional engines such as the piston engine, gas turbine and Wankel rotary engine. A simulation procedure proved that the new concept engine is functional, and has many potential advantages compared to the existing conventional engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.178-185
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• 2006

This paper investigates the steady-state combustion characteristics of the Homogeneous charge compression ignition(HCCI) engine with variable valve timing(VVT) and dimethyl ether(DME) direct injection, to find out its benefits in exhaust gas emissions. HCCI combustion is an attractive way to lower carbon dioxide($CO_2$), nitrogen oxides(NOx) emission and to allow higher fuel conversion efficiency. However, HCCI engine has inherent problem of narrow operating range at high load due to high in-cylinder peak pressure and consequent noise. To overcome this problem, the control of combustion start and heat release rate is required. It is difficult to control the start of combustion because HCCI combustion phase is closely linked to chemical reaction during a compression stroke. The combination of VVT and DME direct injection was chosen as the most promising strategy to control the HCCI combustion phase in this study. Regular gasoline was injected at intake port as main fuel, while small amount of DME was also injected directly into the cylinder as an ignition promoter for the control of ignition timing. Different intake valve timings were tested for combustion phase control. Regular gasoline was tested for HCCI operation and emission characteristics with various engine conditions. With HCCI operation, ignition delay and rapid burning angle were successfully controlled by the amount of internal EGR that was determined with VVT. For best IMEP and low HC emission, DME should be injected during early compression stroke. IMEP was mainly affected by the DME injection timing, and quantities of fuel DME and gasoline. HC emission was mainly affected by both the amount of gasoline and the DME injection timing. NOx emission was lower than conventional SI engine at gasoline lean region. However, NOx emission was similar to that in the conventional SI engine at gasoline rich region. CO emission was affected by the amount of gasoline and DME.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.26-33
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• 2007

The intake swirl motion, as one of dominant effects for an engine combustion. is very effective for turbulence enhancement during the compression process in the cylinder of 2-valve engine. Because the combustion flame speed is determined by the turbulence that is mainly generated from the mean flow of the charge air motion in intake port system. This paper describes the experimental results of swirl flow and combustion characteristics by using the oil spot method and back-scattering Laser Doppler velocimeter (LDV) in 2-valve single cylinder transparent LPG engine using the liquid phase LPG injection. For this. various intake port configurations were developed by using the flow box system and swirl ratios for different intake port configurations were determined by impulse swirl meter in a steady flow rig test. And the effects of intake swirl ratio on combustion characteristics in an LPG engine were analyzed with some analysis parameters that is swirl ratio. mean flow coefficient, swirl mean velocity fuel conversion efficiency. combustion duration and cyclic variations of indicated mean effective pressure(IMEP). As these research results, we found that the intake port configuration with swirl ratio of 2.0 that has a reasonable lean combustion stability is very suitable to an $11{\ell}$ heavy-duty LPG engine with liquid phase fuel injection system. It also has a better mean flow coefficient of 0.34 to develope a stable flame kernel and to produce high performance. This research expects to clarify major factor that effects on the design of intake port efficiently with the optimized swirl ratio for the heavy duty LPG engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.10-16
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• 2004

The Homogeneous Charge Compression Ignition (HCCI) engine has advantage for reducing the NOx and P.M. simultaneously. Therefore, HCCI engine is receiving attention as a low emission diesel engine concept. This study was carried out to investigate the characteristics of combustion and exhaust emission for operating conditions in a direct injection type of HCCI engines such as supercharged and naturally aspirated using diesel fuel and additive. From the experimental result, we found that cool flame was always appeared and also it was difficult to control combustion characteristics by changing the injection timing in HCCI. In addition, at the lean air-fuel ratio and high speed range, it was observed that charging air pressure, additive or increasing intake air temperature is effective to increase combustion performance and reduce exhaust emission. We concluded that chemical reaction by the increasing intake air temperature or additive without physical improvement has limitation for reduction of exhaust emission.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.378-384
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• 2012

Higher compression ratio is required in diesel engine to ignite the fuel that leads to better efficiency. For complete combustion inside the cylinder it is important to ensure the clean air flow with free of debris and as cool as possible. In this manner, modification of intake valve arrangements is taken in to consideration importantly. In this paper, the intake valve arrangements are modified with newly designed valve mixer. It causes swirl flow of air through the intake port that mixing with the fuel followed by complete combustion. The use of valve mixer reduces the carbon sediment formation on valve fillet and its face area as the carbon particles gradually take place on it after certain running period. It therefore, helps to increase the valve lifetime. And at the same time it reduces the exhaust elements i.e. soot from the automobiles to a significant level.