• 한국연소학회:학술대회논문집
• /
• 2014.11a
• /
• pp.343-344
• /
• 2014

Ethanol as fuel of Spark Ignition Direct Injection (SIDI) engine has become a feasible alternative due to its better anti-knock characteristics and lower nano-particle emission level. There are a number of studies on the emission characteristics from SIDI engine fuelled with various ethanol contents. In general, increase of ethanol contents leaded to decrease of nano-particle discharge, but the other researches showed reversed result at a singular range of ethanol contents. This study focused on the engine combustion performance and nano-particle emission characteristics of SIDI engine fuelled with intermediate ethanol contents.

• International Journal of Automotive Technology
• /
• v.7 no.4
• /
• pp.459-468
• /
• 2006

The objective of this paper is the development of the forward-looking dynamic simulation model of a hybrid electric vehicle(HEV) for a fuel economy study. The specification of the vehicle is determined based on two factors, engine peak power to curb weight ratio and specific engine power. The steady state efficiency models of the powertrain components are explained in detail. These include a spark ignition direct injection(SIDI) engine, an integrated starter alternator(ISA), and an infinitely variable transmission(IVT). The paper describes the integration of these models into a forward facing dynamic simulation diagram using the AMESim environment. Appropriate vehicle and driver models have been added and described. The controller was designed in Simulink and was combined with the physical powertrain model by the co-simulation interface. Finally, the simulation results of the HEV are compared with those of a baseline vehicle in order to demonstrate the fuel economy potential. Results for the vehicle speed error and the fuel economy over standard driving cycles are illustrated.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.9
• /
• pp.722-727
• /
• 2009

The effect of the intake flow on the spray structure of a high pressure 11-hole fuel injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing and in-cylinder charge motion were investigated using the 2-dimensional Mie scattering technique. It was confirmed that in the homogeneous charge mode, the in-cylinder swirl charge motion played a major role in the fuel spray distribution during the induction stroke rather than the tumble flow. But, in the stratified charge mode, the effect of the in-cylinder charge was not so large that the injected spray pattern was nearly maintained and the increase of in-cylinder pressure by the upward moving piston reduced the fuel spray penetration.

• International Journal of Automotive Technology
• /
• v.6 no.6
• /
• pp.555-561
• /
• 2005

This experimental study was executed to obtain basic data for actual engine operation using radical induced ignition method (RI) which can achieve emission reduction and high efficiency due to the rapid bulk combustion. In this study, a direct injection diesel engine was converted into SI type engine with a sparkplug. The modified SI type engine can be divided into two classes. One is the SI engine with a sparkplug only at the cylinder head, and the other is the SI engine with the sparkplug which is enveloped in a sub-chamber. Also, a basic experimental was conducted in order to investigate combustion mechanism of radical induced injection before the experiment execution for actual engine using the modified SI engine. The bulk combustion phenomenon of radical induced ignition method was analyzed from the basic experiment by using a constant volume chamber. Volume value of sub-chamber used in this experiment is approximately $0.2\%$ of one of the main combustion chamber. In this paper, combustion characteristics using radical induced injection method was compared with that of using spark ignition method according to change in the engine speed and equivalence ratio. As a result, in the case of the radical induced injection engine, the combustion duration and cycle variation were respectively reduced ranged from $\Phi$(equivalence ratio)=0.8 (lean mixture ratio) to $\Phi$=1.0 (stoichiometric ratio).

• Journal of ILASS-Korea
• /
• v.23 no.2
• /
• pp.96-101
• /
• 2018

The purpose of this study is to investigate the effect of water injection on combustion characteristics of gasoline direct injection (GDI) engine with turbo-charger under low-load operating condition. The test engine used in this study has four-cylinder and 10.2 of compression ratio. In order to study the effect of water injection ratio on combustion characteristics, the water was injected into the intake port from 10% to 50%, based on fuel injection quantity. From the experiment, it revealed that the water injection induced the improvement of fuel economy because of the advance of spark-timing by the reduction of in-cylinder temperature. In addition, the water injection caused the prolong of extension of the ignition delay and slight increase of burn duration.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.9
• /
• pp.1317-1324
• /
• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.1
• /
• pp.19-27
• /
• 2005

The spray characteristics of DISI injector has a great role in engine efficiency and emission. Thus, many researchers have been studied to investigate the spray characteristics of hollow cone type and slit type injector which are used in DISI engine. In this study, we tried to provide spray parameters which effect on the spray characteristics such as injection pressure, ambient pressure and ambient temperature. In addition, we calculated $t_b\;and\;t_c$ to investigate the break up mechanism of test injectors and also obtained $C_v$ to evaluate the spray characteristics. From this study, As the ambient pressure increases in case of slit injector, $C_v$ decreases.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.5
• /
• pp.54-66
• /
• 2000

A gasoline direct injection single cylinder engine has been developed to study operational characteristics for highly stratified conditions. Parameters related to design and experiment were also studied to understand the characteristics of combustion and emissions at some part load conditions. It was found that optimal timings between the end of fuel injection and spark ignition were existed for stable combustion under the stratified modes, In a low engine speed, fuel spray behavior around piston bowl was important for stable combustion. The in-cylinder air motion affecting fuel spray behavior was found to be a dominant factor at higher engine speed as fuel injection timing had to be advanced to secure enough time for fuel evaporation and mixing with surrounding air. As swirl ratio increased, spark timing could be advanced for stable combustion and a higher compression ratio could be used for improved fuel consumption and stable combustion at the stratified mode. It was also observed that electrode geometry and piston bowl shape played an important role for combustion and emission characteristics and some results were shown for comparison.

• Journal of ILASS-Korea
• /
• v.28 no.4
• /
• pp.198-206
• /
• 2023

In this study, visualization of in-cylinder spray behavior and spark channel stretching by air flow characteristics depending on engine operating conditions were investigated. For in-cylinder spray behavior, increase in engine rpm did not alter the counter-clockwise air flow direction and location of in-cylinder dominant air flow but increased average air flow velocity, which hindered spray propagation parallel to the piston surface. When injection timing was retarded, direction of in-cylinder dominant air flow was changed, and average air flow velocity was reduced resulting in an increase in spray penetration length and change in direction. For spark channel stretching, increase in air flow speed did not affect spark channel stretch direction but affected length due to increase in spark channel resistance and limitation of energy ignition coil can handle. Change in air flow direction affected spark channel stretch direction where the air flow was obstructed by ground electrode which caused spark channel direction to occur in the opposing direction of air flow. It also affected spark channel stretch length due to change in air flow speed around the spark plug electrode from the interaction between the air flow and ground electrode.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.32 no.11
• /
• pp.878-883
• /
• 2008

The spray characteristics of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played a major role in the fuel spray distribution during the induction stroke while the propagation of fuel spray was restrained during the compression stroke by the increasing pressure and the upward moving piston. In additions, it was confirmed that the liquid fuel droplets existing at the sprays edges were vaporized by the increase of the coolant temperature.