• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1744-1759
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• 1992

A multidimensional simulation of turbulent flow and combustion with swirl in the cylinder of SI engine is implemented to clarify the effects of swirl. present simulation employs the ICED-ALE numerical technique, the skew-upwind difference scheme, a modified k_.epsilon. turbulence model, a combustion model of Arrhenius type and turbulence-mixing-control type. First, the calculations for swirling flow in an axisymmetric cylinder are carried out. The results are compared with the experimental data to validate the numerical analysis. Second, the calculations for intake, compression and combustion processes in an axisymmetric cylinder are performed. The effects of swirl on turbulent flow and combustion are examined through the parametric study of swirl number 0.0, 0.6, 1.2 and 2.4. As a result, it is numerically shown that the turbulent kinetic energy and the swirl velocity, which are produced during the intake process, affect the combustion process.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.9
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• pp.826-834
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• 2007

A 7K60MC-S low speed diesel engine in a power plant has frequently experienced high vibration since the unit completed construction works. Up to date, no fundamental vibration solutions were reached. Hence, several vibration tests and analyses were conducted to identify the root cause of this high vibration and to suggest the optimal countermeasures for diesel engine. The 9.25 Hz and 25.4 Hz vibrations have been observed on main body during operation. The magnitude of engine upper structural vibration is generally similar in horizontal transverse direction. However, differences in the 'Fore' and 'After' vibration magnitude with the same vibration phase angle at 9.25 Hz occur due to the explosion pulsations of 7 cylinders and the Inertia momentum added by the SCR (selective catalytic reduction) duct system. It was analyzed that the excess structural vibration occurred when the natural frequency of engine body is affected by the exciting sources due to the explosion pressure and the discharge pulsation of the seven cylinders in resonance range.

• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1588-1598
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• 2001

The effects of recirculated exhaust gas on the characteristics of NOx and soot emissions under a wide range of engine loads were experimentally investigated by using a four-cycle, four-cylinder, sw irl chamber type, water-cooled diesel engine operating at three engine speeds. The purpose of this study was to develop the EGR-control system for reducing NOx and soot emissions simultaneously in diesel engines. The EGR system is used to reduce NOx emissions, and a novel diesel soot removal device with a cylinder-type scrubber for the experiment system was specially designed and manufactured to reduce soot contents in the recirculated exhaust gas to the intake system of the engine. The experiments were performed at the fixed fuel injection timing of 4$^{\circ}$ ATDC regardless of experimental conditions. It was found that soot emissions in exhaust gases were reduced by 20 to 70% when the scrubber was applied in the range of the experimental conditions, and that NOx emissions decreased markedly, especially at higher loads, while soot emissions increased owing to the decrease in intake and exhaust oxygen concentrations, and the increase in equivalence ratio as the EGR rate is elevated.

• Journal of Korea Foundry Society
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• v.24 no.4
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• pp.225-230
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• 2004

Computer simulation of mold filling and solidification has been performed in order to analyze the flow and solidification phenomena for the casting process of cylinder liner. The simulation result of mold filling shows that the molten metal flows into the mold in stable without scattering. The simulation results of solidification indicate that the last solidified area is located in the feeder. The temperature variation in casting is measured in actual casting and the result is compared with calculation result.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.22-30
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• 1996

In-cylinder flow of a purpose-built small HSDI Hydra Diesel engine was investigated by laser Doppler velocimetry(LDV) during induction and compression processes. The flow was quantified in terms of ensemble-averaged axial and swirl velocities, normalized by the mean piston speed, at a plane located 12mm from the cylinder head and corresponding to the mid-plane of the diametrically-opposed quartz windows at an enigne speed of 1000rpm. The formation of toroidal vortices during the intake process and the evolution and decay of swirl motion during the compression process were observed. Turbulence at around TDC of compression became homogeneous and isotropic.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.436-444
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• 1998

Applicability of the RNG k-$\varepsilon$ model to the analysis of unsteady axisymmetric turbulent flow of a reciprocating engine including port/valve assembly is studied numerically. The governing equations based on non-orthogonal including port/valve assembly is studied numerically. The governing equations based on a non-orthogonal coordinate formulation with Cartesian velocity components are used and discretised by the finite volume method with non-staggered variable arrangements. The predicted results using the RNG k-$\varepsilon$ model of the unsteady axisymmetric turbulent flow within a cylinder of reciprocating model engine including port/valve assembly are compared to these from the modified k-$\varepsilon$ model and experimental data. Using the RNG k-$\varepsilon$ model seems the have some potential for the simulations of the unsteady turbulent flow within a port/valve-cylinder assembly over the modified k-$\varepsilon$model.

• Journal of the korean Society of Automotive Engineers
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• v.2 no.1
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• pp.51-60
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• 1980

Experiments about engine performance using alcohol-gasoline blend as a fuel are studied. A conventional 4cycle 4cylinder gasoline engine is used. Measurements on torque, output, specific fuel consumption, and emissions are made over ignition timing and mixing ratio. Up to vol. 15% of alcohol, torque and output using alcohol-gasoline blend are almost same with using only gasoline, and specific fuel consumption is improved about 7%. In emissions alcohol-gasoline blend is more effective than gasoline.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.18-25
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• 2000

Ion current in an S.I engine cylinder is measured with the spark plug as a probe. The peak values are confirmed to show a fair correlation with local air-fuel ration and engine speed which implies that the ion current measured at the spark plug may provide a signal for the local mixture strength which is the key parameter in precise fuel control for future engines especially of gasoline direct-injected lean burn engines.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.209-220
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• 2001

This study was carried out to investigate the usability of the used frying oil, which was extracted from soybean, as one of the alternative fuel of a small diesel engine. For the experiment, NO. 2 diesel oil [D], used frying oil [UF], and their volumetric blends were applied and analysis of the properties and compositions of the experimental fuels were conducted. A four cycle diesel engine with single cylinder, water cooling system, maximum output 8.1 ㎾/2,200 rpm was selected and a direct injection chamber and a precombustion chamber were attached alternately. The results obtained were as follows: 1. Engine power (BHP) were increased from 4.13~4.27㎾ to 9.08~9.15㎾ for diesel oil, from 4.05~4.19㎾ to 8.44~8.92㎾ for UF, and from 4.01~4.48㎾ to 8.69~9.16㎾ for blend fuel, as the engine speed increased from 1,000 rpm to 2,200 rpm. The BHP in case of the direct combustion chamber were fluctuated higher than those of the pre-combustion chamber. 2. With the engine speed increased, torque of the engine were increased from 39.50~40.80 N.m to 42.89 N.m, then decreased to 39.44~39.77 N.m for diesel oil, and increased from 38.73~40.04 N.m to 40.12~40.82 N.m then decreased as 36.53~38.76 N.m for UF. Torque of the blend fuels were increased from 38.75~41.76 N.m to 40.47~42.89 N.m then decreased to 37.73~39.78 N.m. There is no significant difference of torque between the type of combustion chambers. 3. The specific fuel consumption of the UF was increased about 20 percent depending on the engine speed variations. And in case of direct injection chamber, about 12 percent lower fuel consumption was observed than that of precombustion chamber. 4. NOx emission of the UF was higher than that of diesel oil at above 1,800rpm of the engine speed. In case of the direct injection chamber, NOx emission was revealed higher about 59 percent than that of the precombustion chamber, depending on the range of the engine speeds. 5. Smoke emission was decreased in case of UF compared with diesel oil on direct injection chamber. When using precombustion chamber smoke emission was a little higher than that of the direct injection chamber were showed at the engine speed range. 6. At all the engine speed range, exhaust gas temperatures were decreased 2~3$^{\circ}C$ for UF used engine compared with those of the diesel oil. The exhaust gas temperature of the direct injection chamber was higher than that of the precombustion chamber by 72$^{\circ}C$. 7. Unburnt materials remained in the cylinder in case of the pre-combustion chamber was smaller and softer than that of the direct combustion chamber. 8. The feasibility of the blend fuel B-1 and B-2 were verified as a direct combustion chamber was attached to the diesel engine, with respect to the power performance of the engine.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2030-2038
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• 1995

In this study, three turbulent flame propagation models are compared using experimentally measured data of a 4 valves/cylinder spark-ignition engine. First two conventional models are B.K model and GESIM combustion model. The burning rates calculated from the two models are compared with the burning rates calculated from measured pressure data using the one-zone heat release analysis. GESIM combustion model predicts burning rates closer to the data acquired from the experiment in wide operating ranges than B-K model does. The third model is refined based on GESIM combustion model by including the effect of flame stretch, turbulent length scale band pass filter and a variable that considers flame size and the area of flame contacting the cylinder wall surface. The refined combustion model predicts burning rates closer to experimental results than GESIM combustion model does. Also, the refined combustion model predicts flame radius close to the experimental result measured by using optical fiber technique.