• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.163-164
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• 2003

Reaction dynamics plays an essential role in understanding the microscopic mechanism of elementary chemical processes at the molecular level. Detailed studies of the reactions of atomic species such as hydrogen and second-row atoms with small closed-shell molecules have provided important insights into hydrocarbon synthesis, combustion, interstellar space and atmospheric chemistry. Despite its mechanistic significance, however, the investigations of atom-radical reaction dynamics are quite scarce in comparison to the extensive studies of atom-molecule reactions. (omitted)

• Journal of the Korean Society of Combustion
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• v.12 no.3
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• pp.33-39
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• 2007

The present study is mainly motivated to investigate the vaporization, auto-ignition and combustion processes in high-pressure engine conditions. In order to realistically simulate the dimethyl ether (DME) spray dynamics and vaporization characteristics in high-pressure and high-temperature environment, the high-pressure vaporization model is utilized. The interaction between chemistry and turbulence is treated by employing the Representative Interaction Flamelet (RIF) model. The detailed chemistry of 336 elementary steps and 78 chemical species is used for the DME/air reaction. Numerical results indicate that the RIF approach, together with the high-pressure vaporization model, successfully predicts the essential feature of ignition and spray combustion processes.

• Journal of the Korean Society of Combustion
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• v.23 no.1
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• pp.21-27
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• 2018

The effect of swirl flow structures on combustion dynamics of two interacting, lean-premixed flames was experimentally investigated, with a particular emphasis on swirl numbers and swirl rotational directions. Our results show that the amplitude of limit cycle oscillations is very sensitive to the combination of swirl numbers and rotational directions, while the instability frequency remains nearly unchanged. The counter-rotating cases show significantly lower pressure perturbations, and this behavior appears to be related to the formation of compact interacting zone with higher heat release rate, indicating the presence of increased flame surface wrinkling caused by intense turbulence.

• Journal of the Korean Society of Combustion
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• v.13 no.3
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• pp.33-40
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• 2008

Two- and Three- dimensional numerical simulations are carried out to understand the combustion characteristics of LNG-fueled gas turbine combustor for power generation using imported and domestic natural gases. Reacting flow characteristics of the swirl stabilized natural gas combustor were understood from the numerical results with the flow conditions selected from the gas turbine operation data. The thermal influences of different natural gases were very small and the fuel composition and flow rate were considered to be tuned well. The flow structures of the recirculation and combustion region was understood from the comparison of the two- and three-dimensional results. The complexity of the three-dimensional swirl flows inside the gas turbine combustor with multiple swirlers was understood those resulting from the interactions of the stage and pilot burners.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.49-59
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• 1998

The vaporization characteristics and spray combustion processes in the high-pressure environment are numerically investigated. This study employ the high-pressure vaporization model together with the state-of-art spray submodels. The present high-pressure vaporization model can account for transient liquid heating, circulation effect inside the droplet forced convection, Stefan flow effect, real gas effect and ambient gas solubility in the liquid droplets. Computations are carried out for the evaporating sprays, the evaporating and burning sprays, and the spray combustion processes of the turbocharged diesel engine. Numerical results indicate that the high-pressure effects are quite crucial for simulating the spray combustion processes including vaporization, spray dynamics, combustion, and pollutant formation.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.252-257
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• 2010

The availability of the thermal energy has been deeply recognized recently to encourage the cascade usage of thermal energy from combustion. Within the frame work, a 1 kW class Stirling engine based cogeneration system has been proposed for a unit of a distributed energy system. The capacity has been designed to be adequate for the domestic usage, which requires high compactness as well as low emission and noised. To develop a highly efficient system with satisfying these requirements, a premixed slot flame burner has been proposed and a series of numerical simulation has been performed to establish a design tool for the combustion chamber. The thermal radiation model has been found to highly affect the computational results and a proper resolution to analyze the heat transfer characteristics of the high temperature heat exchanger. Finally, the combustion characteristics of the premixed flame with the metal fiber type burner has been studied.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.369-376
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• 2015

Recently KEPCO, KOGAS and other institutions are jointly conducting an R&D for the development and demonstration of the power generation system based on a natural gas/diesel engine on an island. As a preliminary study, co-combustion in the dual fuel engine, which is expected to produce a few mega-watts of electricity, was modeled and calculated using computational fluid dynamics (CFD). The applied key assumptions are 2-dimensional axisymmetric, transient and static volume chemical reaction. Based on the selected blending ratio, which is the key operating condition, natural gas is substituted instead of diesel fuel (basis of high heating value). Results showed that as the blending ratio increases, the reaction rate of the combustion increases and thus maximum temperature is reached more rapidly. For the optimal performance, various geometric or operational studies will further be conducted.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.103-111
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• 2019

The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.15-23
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• 2019

In this study, an extinguishment model of a three-dimensional solid propellant rocket was developed by combustion and fast depressurization to control the thrust of a solid rocket. Computational fluid dynamics simulation was carried out to ascertain the change in flow patterns in the combustion chamber and the extinguishment process by using a pintle. An ammonium perchloride was used as the target propellant and the dynamic behavior of its major parameters such as temperature, pressure, and burning rate was predicted using the combustion model. The dynamic behavior of the combustion chamber was confirmed by fast depressurization from an initial pressure of 7 MPa to a final pressure of 2.5 MPa at a depressurization rate of approximately -912 MPa/s.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.37-43
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• 2011

The present study conducted computational simulation for multiphase flow in the flame spray coating process with commercially available Ni-Cr powders. The flows in a flame spray gun is characterized by very complex phenomena including combustion, turbulent flows, and convective and radiative heat transfer. In this study, we used a commercial computational fluid dynamics (CFD) code of Fluent (ver. 6.3.26) to predict gas dynamics involving combustion, gas and particle temperature distributions, and multi-dimensional particle trajectories with the use of the discrete phase model (DPM). We also examined the effect of particle size on the flame spray process. It was found that particle velocity and gas temperature decreased rapidly in the radial direction, and they were substantially affected by the particle size.