• 한국연소학회:학술대회논문집
• /
• 2012.11a
• /
• pp.229-231
• /
• 2012

A numerical analysis of a lean premixed combustor in a micro gas turbine was carried out to investigate the correlation between the turbulent mixing and emission characteristics on the combustor geometries. The interaction between the burners, by flow direction and momentum, significantly influenced on the turbulent mixing and combustion characteristics. The vortex which was generated by thermal expansion was observed during the combustion process, this was distinguished from the combustor geometries. The results showed that these characteristics can affect the NOx emission.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.493-495
• /
• 2005

This paper proposes a swarm-based fuzzy system modeling technique for coke oven combustion control diagnosis. The coke plant produces coke for the blast furnace plant in steel making process by charging coal into oven and supplying gas to carbonize it. A conventional mathematical model for coke oven combustion control has been used to control the amount of gas input, but it does not work well because of highly nonlinear feature of coke plant. To solve this problem, swarm-based fuzzy system modeling technique is suggested to construct a diagnosis model of coke oven combustion control. Based on the measured input-output data pairs, the fuzzy rules are generated and the parameters are tuned by the PSO(Particle Swarm Optimizer) to increase the accuracy of the fuzzy system is operated. This system computes the proper amount of gas input taking the operation conditions of coke oven into account, and compares the computed result with the supplied gas input.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.2186-2191
• /
• 2003

This study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in diesel engine. The effects of water induction through the air intake port were considered in IDI diesel engine in this study. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased with increased water amount. Also, NOx significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions can be obtained when water is injected into the combustion chamber by retarding the fuel injection timing more than without water injection.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.3
• /
• pp.763-770
• /
• 1995

Gas flow characteristics within the cylinder is important factors in impoving lean combustion stability. This paper shows the effects of various flow fields generated by a swirl control valve(SCV) on combustion process in a 4-valve spark ignition engine. An impulse swirl/tumble meter was used to elucidation the steady-state flow characteristics, and a rotating grating type LDV was developed to measure the mean velocity and tunbulence intensity in relation to the crank angle. These methodologies were applied to clarify the correlation between gas flow characteristics and combustion stability at a lean air fuel ratio. An analysis of the correlation revealed the gas flow conditions required to optimize a lean-burn system.

• 한국전산유체공학회:학술대회논문집
• /
• 1998.05a
• /
• pp.117-122
• /
• 1998

A numerical study is carried out to investigate the transient process of combustion phenomena associated with hypersonic propulsion devices. Reynolds averaged Navier-Stokes equations for reactive flows are used as governing equations with a detailed chemistry mechanism of hydrogen-air mixture and two-equation SST turbulence modeling. The governing equations are discretized by a high order accurate upwind scheme and solved in a fully coupled manner with a fully implicit time accurate method. At first, oscillating shock-induced combustion is analyzed and the comparison with experimental result gives the validity of present computational modeling. Secondly, the model ram accelerator experiment was simulated and the results show the detailed transient combustion mechanisms. Thirdly, the evolution of oblique detonation wave is simulated and the result shows transient and final steady state behavior at off-stability condition. Finally, shock wave/boundary layer interaction in combustible mixture is studied and the criterion of boundary layer flame and oblique detonation wave is identified.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.2
• /
• pp.225-231
• /
• 1998

Flame propagation speed characteristics of methante-air mixtures were experimentally investigated in combustion chamber modelled engine. Flame propagation process was known as a funtion of equivalence ratio initial pressure and initial temperature. Ion probe and schlieren photograph were applied to measure the local flame speed and flame radius in quiescent mixtures. Pressure was also measured to make sure of the reproducibility and to apply combustion analysis. Burning velocity was calculated from the flame propagation speed and combustion analysis. Flames were developed faster with higher initial pressure and initial temperature but showed maximum propagation speed at equivalence ratio 1.1 regardless of initial pressure and temperature. Local flame speed was maximum values at near midpoint between center and wall.

• Journal of ILASS-Korea
• /
• v.19 no.3
• /
• pp.109-114
• /
• 2014

The main purpose of this study is to provide basic information of droplet burning, extinction process and flame behavior of methanol fuel and improve the ability of theoretical prediction of these phenomena. For the improved understanding of these phenomena, this paper presents the experimental results on the methanol droplet combustion conducted under various initial droplet diameters ($d_0$), ambient pressure ($P_{amb}$), and oxygen concentration ($O_2$) conditions. To achieve this, the experimental study was conducted in terms of burning rate (K) with normalized droplet diameter ($d/d_0$), flame diameter ($d_f$) and flame standoff ratio (FSR) under the assumptions that the droplet combustion can be described by both the quasi-steady behavior for the region between the droplet surface and the flame interface and the transient behavior for the region between the flame interface and ambient surrounding.

• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.159-165
• /
• 2003

This paper describes numerical efforts to characterize the flame-holding and air-fuel mixing process of model SCRamjet engine combustor, where a hydrogen jet injected into a supersonic cross flow and in a cavity. Combustion phenomena in a model SCRamjet engine, which has been experimentally studied at University of Queensland and Australian National University using a free-piston shock tunnel, was observed around separation region of upstream of the normal injector and inside of cavity. The results show that the separation region and cavity generates several recirculation zones, which increase the fuel-air mixing. Self ignition occurs in the separation-freestream and cavity-freestream interface.

• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.57-61
• /
• 2003

In the combustion modeling of non-premixed flames, the mixture fraction conserved scalar approach is widely utilized because reactants are mixed at the molecular level before burning and atomic elements are conserved in chemical reactions. In the mixture fraction approach, combustion process is simplified to a mixing problem and the interaction between chemistry and turbulence could be modelled by many sophisticated combustion models including the flamelet model and CMC. However, most of the mixture fraction approach is restricted to one mixture system. In this study, the flamelet model based on the two-feed system is extended to the multiple fuel-feeding systems by the two mixture fraction conserved scalar approach.

• Journal of the Korean Society of Combustion
• /
• v.7 no.2
• /
• pp.42-48
• /
• 2002

Experiments on burning process of the industrial wastes were performed on a nozzle-type grate in the industrial waste incinerator with a capacity of 160 kilograms per hour. The temporal variations of temperatures and concentrations of the exhaust gas were measured and analyzed. The synthetic leather waste with the moisture content less than 2% was used. The experimental results show that the CO concentration in the exhaust gas exceeds the limit, 600 ppm, and the gas temperature fluctuates too much when 8 kg of waste was supplied every 3 minutes, equivalent to the capacity of 160kg per hour. That is a typical burning mode of this high-calorific industrial waste. When the smaller unit waste input, 6kg per every 2 min 15 seconds was supplied, we could reduce the fluctuations of the furnace temperature and improve the exhaust emissions, especially the CO concentration.