• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.37-42
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• 2001

This paper computes the bluff-body stabilized jet and flame. This study numerically investigates the nonpremixed $C_{2}H_{4}-air$ jet for the nonreacting case and the nonpremixed $CH_{3}OH-air$ turbulent flames for the reacting case using the laminar flamelet model on modified KIVA2 code. And this study predicts $NO_{x}$ formation characteristics using Eulerian Particle Flamelet Model. In the present study, the turbulent combustion model is applied to analyze both nonreacting and reacting case. And both standard $k-{\varepsilon}$ model and modified $k-{\varepsilon}$ model are used in nonreacting case. Calculations are compared with experimental data in terms of velocity, mixture fraction, mixture fraction Root Mean Square and Temperature. The present model correctly predicts the essential features of flame structures and $NO_{x}$ formation characteristics in the bluff-body stabilized flames.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
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• pp.165-170
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• 1998

Turbulent nonpremixed $H_2$-air jet flames are numerically investigated using the joint PDF model. The reaction progress variable is derived by assuming the radicals 0, H, and OH to be in partial equilibrium and additional species $HO_2$ and $H_2O_2$ in steady state. The model is extended to npnadiabatic flame by introducing additional variable for the transport of enthalpy and radiative source term is calculated using a local, geometry independent model. In terms of flame structure and NO formation, the predicted results are favorably agreed with experimental data. The effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• 한국연소학회지
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• 제14권2호
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• pp.32-41
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• 2009

The transported probability density function model combined with the consistent finite volume (FV) method has been applied to simulate the turbulent bluff-body reacting flows. To realistically account for the non-isotropic turbulence effects on the turbulent bluff-body reacting flows, the present PDF transport approach is based on the joint velocity- turbulent frequency-composition PDF formulation. The evolution of the fluctuating velocity of a particle is modeled by a simplified Langevin equation and the particle turbulence frequency is represented by the modified Jayesh - Pope model. Effects of molecular diffusion are represented by the interaction by exchange with the mean (IEM) mixing model. To validate this hybrid FV/PDF transport model, the numerical results are compared with experimental data for the turbulent bluff-body reacting flows.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.167-172
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• 2004

The present study has focused on numerical investigation on the flame structure, flame lift-off and stabilization in the partially premixed turbulent lifted jet flames. Since the lifted jet flames have the partially premixed nature in the flow region between nozzle exit and flame base, level set approach is applied to simulate the partially premixed turbulent lifted jet flames for various fuel jet velocities and co-flow velocities. The flame stabilization mechanism and the flame structure near flame base are presented in detail. The predicted lift-off heights are compared with the measured ones.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.220-220
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• 2003

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2372-2377
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• 2007

Characteristics of turbulent lifted flames in coflow jets with the varying initial temperature have recently been investigated about only propane case diluted by nitrogen. The investigation has firstly improved a premixed flame model and a large scale mixing model among competing theories on the stabilization mechanism of turbulent flame to be suitable for a high temperature condition. In this research, about methane with good availability to apply for a practical combustor as clean fuel, its characteristics of turbulent nonpremixed flame have been studied experimentally. The results have shown an effectiveness of the premixed flame model and the large scale mixing model considered initial temperature variation. Additionally, considering the axial distance where the mean fuel concentration falls below the stoichiometric level along the center line of the jet according to diluting nitrogen, the premixed flame model have more accurately been improved.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.219-222
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• 2014

The flame chemiluminescence is a good tracer of flame statement. In this study, the characteristics of flame chemiluminescence($OH^*$, $CH^*$, ${C_2}^*$) according different measuring locations using photomultiplier(PMT), spectrometer and CCD camera. Measurements are made for $OH^*$, $CH^*$, ${C_2}^*$ radicals in gas & light oil diffusion flames. At turbulent nonpremixed combustion mode, the equivalence ratio is varied. The experimental results showed that measuring location affects the result of flame chemiluminescence.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.88-97
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• 2001

The present study numerically investigates the fuel-air mixing characteristics, flame structure, and pollutant emission inside a double-swirler combustor. A PSR(Perfectly Stirred Reactor) based microstructural model is employed to account for the effects of finite rate chemistry on the flame structure and NO formation. The turbulent combustion model is extended to nonadiabatic flame condition with radiation by introducing an enthalpy variable, and the radiative heat loss is calculated by a local, geometry-independent model. The effects of turbulent fluctuation are taken into account by the joint assumed PDFs. Numerical model is based on the non-orthogonal body-fitted coordinate system and the pressure/velocity coupling is handled by PISO algorithm in context with the finite volume formulation. The present PSR-based turbulent combustion model has been applied to analyze the highly intense turbulent nonpremixed flame field in the double swirler combustor. The detailed discussions were made for the flow structure, combustion effects on flow structure, flame structure, and emission characteristics in the highly intense turbulent swirling flame of the double swirler burner.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.61-62
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• 2012

The present study has numerically investigated the effects of fuel-side dilution and pressure on flame structure and extinction scalar dissipation rate of turbulent syngas nonpremixedd flames. Numerical results indicate that for highly diluted case, peak temperature is decreased and stoichiometric mixture fraction is increased. By decreasing the pressure and the nitrgen dilution levelcreased, the extinction scalar dissipation rate is increased.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.71-79
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• 1999

Numerical analysis on the characteristics of nitrogen oxides (NOx) formation in turbulent nonpremixed hydrogen-air flames was carried out. Lagrange IEM model and Assumed PDF model were applied to consider turbulence-chemistry interaction known to affect the production of NOx. Partial equilibrium assumption was used to predict nonequilibrium effect to which one-half power dependence between EINOx normalized by flame residence time and global strain rate is attributed. As a result. such one-half power dependence could be reproduced only by reaction model including $HO_{2}$and $H_{2}O_{2}$, which means its dependence on Damkohler number; nonequilibrium effect. This dependence was shown better in the region of higher global strain. Besides, the improvement of turbulence model is required to predict mean flow properties quantitatively in the radial direction.