• Journal of Advanced Marine Engineering and Technology
• /
• 제18권2호
• /
• pp.97-103
• /
• 1994

This paper describes briefly the simulation program for predicting the performance of a high speed turbocharged four cycle diesel engine. The wave phenomena in the intake and exhaust systems are calculated by the characteristic method. The combustion process in the power cycle is represented by the heat release pattern which is given by the Wiebe's function or the pattern based on measured values. Turbocharger matching for the engine is described by utilizing the characteristic maps of both the compressor and turbine, which are obtained from quasi-steady states. A comparison of experimental and calculated results shows a good agreement. Then the influences of the intake system, the period of valve overlap and the characteristics of the turbine are numerically investigated by the simulation.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
• /
• pp.206-212
• /
• 2004

It is necessary to consider the stability, economic environmental-friendly problems by the development of the road, supply of the automobile, environmental problem as designing the exhaust system. To reduce the noise and the vibration of the automobile, it is needed to consider the pulsation noise, air current noise, vibration of air pipe which generate the intake and exhaust noise of the automobile. Moreover, the discharge sounds, intake sound, radiation sound, transmitted sound are occurred. To reduce this influence, the variable valve is needed and to control these factors, path transformation muffler and active type muffler are needed. While engine efficiency could be reduced with this transformationand resistance by the pressure, thermal property. In this study, how to design exhaust systems yielding higher condversion efficiency, lower backpressure and optimize the performance. this study is recommended for exhaust system and designers and engineers involved in SI engine exhaust system and it will furnish information for you to design more efficient.

• 한국자동차공학회논문집
• /
• 제2권4호
• /
• pp.112-119
• /
• 1994

This study is investigated into the dynamic effect of the manifold configuration during the gas exchange processes using both simulation and experiment, In theoretical study on the flow analysis, the characteristic method is applied to solve the compressible unsteady flow equation, involving the several steady flow boundary conditions. In order to excute the engine experiment efficiently, a data acquisition system is configured by using A/D converter and PC. Good results which coincided experimental data with simulation output were obtained, and it shows that this simulation method can be applied to obtain the optimal design parameters in the intake and exhaust systems.

• 한국자동차공학회논문집
• /
• 제22권7호
• /
• pp.90-97
• /
• 2014

The effects of high pressure and low pressure exhaust gas recirculation (HP/LP EGR) portion on diesel engine combustion and emissions characteristics were investigated in a 2.2 L passenger-car diesel engine. The po3rtion of HP/LP EGR was varied from 0 to 1 while fixing the mass flow rate of fresh air. The intake manifold temperature was lowered with the increasing of the portion of LP EGR, which led to the retardation of heat release by pilot injection. The lowered intake manifold temperature also resulted in low nitrogen oxide (NOx) emissions due to decreased in-cylinder temperature and prolonged ignition delay, however, the carbon monoxide (CO) emission showed opposite trend to NOx emissions. The brake specific fuel consumption (BSFC) was decreased as the portion of LP EGR increased due to lowered exhaust manifold pressure by wider open of turbocharger vane. Consequently, the trade-off relationship between NOx and BSFC could be improved by increasing the LP EGR portion.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.622-625
• /
• 2007

For optimizing the performance of SI engine such as engine torque, fuel consumption, and emissions, systems for variable valve timing were developed by many automotive researchers. In this work, we investigated the relationship between valve timing and intake orifice noise to improve the NVH (Noise, Vibration and Harshness) performance as well as engine torque and power. Two approaches are conducted, which are engine dynamometer testing and 1-D simulation analysis. Experimental data were measured on about 21 different operating conditions. This experiment shows that the intake and exhaust valve timing related to overlap period influence on the NVH performance, especially intake orifice noise of engine at given range of operation conditions. Similar results are achieved by using 1-D simulation analysis. It is concluded that the optimal strategies of controlling valve timing and tuning intake systems, are necessary to develop engines or vehicles with good sound quality.

• 한국자동차공학회논문집
• /
• 제9권5호
• /
• pp.62-74
• /
• 2001

In this study, the prediction of performances and emissions of the gasoline engine of a light passenger car has been accomplished. The method of characteristics including friction, heat transfer, area change and entropy gradients was used to analyze the flow in the intake and exhaust systems. For in-cylinder calculation, the single-zone model was adopted for the periods of the intake, exhaust, compression and the expansion of the burnt gas and the 2-zone expansion model was applied to the period of combustion process. The simulation program was verified by comparison with the experimental values both for the naturally aspirated engine and the turbocharged engine showing good agreements. Using the simulation program, multi-valve system and turbocharging were examined as a means of increasing engine Performances.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.27-33
• /
• 2001

Linear harmonic analysis is a convenient and generally accurate method to use for the acoustic analysis of intake and exhaust silencers for IC engines. The major uncertainty in this form of modelling is the characterisation of the source, which is inherently nonlinear and time-variant. Experimental methods are generally used to determine the source characteristics, and in particular the indirect method is most suitable for an IC-engine source. With reference to an idealised linear time-variant source, it is found that the characteristics of a time-variant source as determined by the indirect method have no physical relevance. The direct method of experimental measurement appears to have some advantage over the indirect method, although in practice it is difficult to apply to an IC engine source. Again, an idealised linear time-variant source can be used to indicate that the characteristics of a time-variant source as determined by the direct method also have no physical relevance. Strangely, these meaningless measured source properties can nevertheless be used to accurately predict the radiated noise from an IC engine and silencer system.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.871-875
• /
• 2001

Evaluation of the contribution of each pass-by noise source to the overall pass-by noise is an important issue for reduction of pass-by noise. A lead-wrapping test for analyzing pass-by noise of motorcycle is used to identify the principal noise sources of the pass-by noise in this study. Lead-wrapping test is employed and the contribution analysis is carried out. Based on the contribution analysis of each pass by noise source from the action of the prior tests, the design modifications of intake/exhaust systems were performed for reducing the pass-by noise. Finally, the pass-by noise test based on ISO362 was carried out to verify the noise reduction.

• 한국분무공학회지
• /
• 제6권1호
• /
• pp.25-34
• /
• 2001

Several efforts to meet the exhaust gas regulation have been undertaken by many researchers in recent years. Main researches are on development of design techniques of intake port and combustion chamber, atomisation of fuel and precise control of air-fuel ratio, post-treatment of exhaust gas and so on. Engine technology is changed from PFI to GDI to correspond with exhaust gas regulation. GDI technique makes it possible to preserve lean air-fuel ratio and control accurate air-fuel ratio. Nevertheless, It is not cleared that information of spray characteristics and atomization process are very dependent on fluctuation of pressure and change of temperature in intake stroke. In this study, a constant volume combustion chamber is manufactured to investigate various fluctuations of in-cylinder pressure for injection duration. It is taken photographs of injection process of conventional GDI injector using PMAS. Then, it was verified experimently that ambient conditions as temperature and pressure of combustion chamber have effects on process of spray growth and atomization of fuel.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2003년도 하계학술대회 논문집
• /
• pp.13-13
• /
• 2003