• 한국연소학회:학술대회논문집
• /
• 2000.12a
• /
• pp.24-32
• /
• 2000

A brief introduction is given on the conditional moment closure model for turbulent nonpremixed combustion. It is based on the transport equations derived through a rigorous mathematical procedure for the conditionally averaged quantities and appropriate modeling forms for conditional scalar dissipation rate, conditional mean velocity and reaction rate. Examples are given for prediction of NO and OH in bluffbody flames, soot distribution in jet flames and autoignition of a methane/ethane jet to predict the ignition delay with respect to initial temperature, pressure and fuel composition. Conditional averaging may also be a powerful modeling concept in other approaches involved in turbulent combustion problems in various different regimes.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.5
• /
• pp.86-96
• /
• 2007

A direct-injection stratified-charge(DISC) engine has been considered as a promising alternative in spite of high unburned hydrocarbon emission levels during light load operation. In this paper investigation is made to characterize formation and combustion processes of stratified mixture charge in a simple constant volume combustion chamber. Both experimental and numerical analyses are performed for fluid and combustion characteristics with 3 different induction types for rich, homogeneous and lean mixture conditions. The commercial code FIRE is applied to the turbulent combustion process in terms of measured and calculated pressure traces and calculated distributions of mean temperature, OH radical and reaction rate. It turns out that the highest combustion rate occurs for the rich state condition at the spark ignition location due to existence of stoichiometric mixture and timing.

• International Journal of Automotive Technology
• /
• v.8 no.3
• /
• pp.275-281
• /
• 2007

GTL (Gas To Liquid) has the potential to be used in diesel engines as a clean alternative fuel due to advantages in emission reduction, particularly soot reduction. Since the physical properties of GTL fuel differ from those of diesel fuel to some extent, studying how this difference in characteristics of GTL and diesel fuels affects spray and combustion in diesel engines is important. In this study, visual investigation of sprays and flames from GTL and diesel fuels in a vessel simulating diesel combustion was implemented. The effects of various parameters and conditions, such as injection pressure, chamber temperature and pilot injection on liquid-phase fuel length and auto-ignition delay were investigated. It was determined that GTL has a somewhat shorter liquid-phase fuel length, which explains why there is less contact between the fuel liquid-phase and flame for GTL fuel compared to diesel fuel.

• Journal of the Korean Society of Safety
• /
• v.19 no.4 s.68
• /
• pp.60-68
• /
• 2004

Consequence analysis of flammable materials that affect to a risk of facilities was studied at the risk based inspection using API-581. We found that consequence areas (damage area of equipment and fatality area) by release accident of flammable materials showed high value for the case of liquid phase and auto-ignition likely, and that consequence areas of flammable gases decreased as temperature increased and the pipe diameter and pressure decreased at continuous release.

• Journal of Powder Materials
• /
• v.5 no.4
• /
• pp.312-318
• /
• 1998

The effect of the mechanical alloying of elemental Mo and Si powders on the combustion densification behavior of MoSi$_2$ was investigated. The ignition temperature of the combustion reaction of the mechanically alloyed powder was measured to be significantly lower than that of the powder mixture prepared by the low energy ball milling process. The densification of the products after the combustion reaction under compressive pressure from the mechanically alloyed powders, however, was found to be poorer than that of the products from the ball milled powder.

• 한국연소학회:학술대회논문집
• /
• 2001.06a
• /
• pp.127-132
• /
• 2001

A numerical study was carried out to investigate the combustion phenomena in a model Scramjet engine, which had been experimentally studied in the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was 2.0 in Mach number and the total temperature of hot flow was 1800K. Equivalence ratio was set to be rather higher value of 0.26 than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• Aerospace Engineering and Technology
• /
• v.11 no.2
• /
• pp.122-128
• /
• 2012

Many of the liquid rocket engines use a hypergolic igniter with rupture disc ends located in the combustion chamber ignition line. In this study, the flow coefficient tests of the igniter, which have a solenoid valve upstream, were performed. The tension-type rupture discs for radial and circumferential scores and the igniter with them were tested using water at room temperature. The effects of the score, flow rate, the disc thickness, gas pocket and the solenoid valve on the coefficient were analyzed.

• Journal of the Korean Ceramic Society
• /
• v.23 no.2
• /
• pp.1-6
• /
• 1986

The mixture of (opalit+Al) powder was ignited by electric shock for the preparation of sialon powder by changin the contents of Al. The formation reaction of sialon was investigated by heating the specimens of ignited mixture (opalit+Al) in nitrogen atmosphere at various temperature. The phases existing inthe specimens nitrided between 1400 and 1$600^{\circ}C$ were found $\beta$-sialon 15R-sia-lon $Al_2O_3$ and AlN but the mixture $\beta$-sialon and 15R-sialon was finally acquired by heating the ignited mixture of (Al 50%+opalit) at 175$0^{\circ}C$ for 3hours in nitrogen atmosphere.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.10
• /
• pp.3381-3386
• /
• 1996

The engine performance and combustion characteristics of methanol blended fuel in spark ignition engine were discussed on the basis of experimental investigation. The effects of methanol blending fuel on combustion in cylinder were investigated under various conditions of engine cycle and blending ratio. The results showed that the engine performance was influenced by the methanol blending ratio and the variations of operating conditions of test engine. The increase of fuel temperature brought on the improvement of combustion characteristics such as cylinder pressure, the rate of pressure rise and heat release in an engine. The burning rate of fuel-air mixture, the exhaust emissions and the other characteristics of performance were discussed also.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.153-156
• /
• 2000

This paper presents an PID type fuzzy based method for nohnear engine idle controller The output is a duty cycle(DC) for driving a idle speed cont개l valve(1SCV). For precise control of SI engine, the CPS sensor and coolant temperature are used. Visual C* language is used to make simulation panel for the fast and precise idle speed control. The dSPACE board and supported Control desk program is used in experiment ta the same purpose as simulation. The experimental results have a good agreement with simulation ones.