• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.198-203
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• 2005

The LES-based level-set flamelet model has been applied to analyze the turbulent propane/air premixed bluff-body flame with a highly wrinkled flame fronts. The present study has been motivated to investigate the interaction between the flame front and turbulent eddies. Special emphasis is given to study the effect of G equation filtering treatment on the precise structure of turbulent premixed flames as well as the effect of sub-grid scale (SGS) eddies on the wrinkling of the flame surface. The level-set/flamelet model has been adopted to account for the effect of turbulence-flame interaction as well as to properly capture the flame front. Numerical results indicate that the present LES-based level-set flamelet approach has a capability to realistically simulate the highly non-stationary turbulent premixed flame.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.75-82
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• 2004

The conditional moment closure(CMC) model has been implemented in context with the unstructured-grid finite-volume method which efficiently handle the physically and geometrically complex turbulent reacting flows. The validation cases include a turbulent nonpremixed $CO/H_2/N_2$ Jet flame and a turbulent nonpremixed $H_2/CO$ flame stabilized on an axisymmetric bluff-body burner. In terms of mean flame field, minor species and NO formation, numerical results has the overall agreement with expermental data. The detailed discussion has been made for the turbulence-chemistry interaction and NOx formation characteristics as well as the comparative performance for CMC and flamelet model.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.139-140
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• 2012

In laminar non-premixed flame situation, the flamelet model is not suitable for simulating slow processor like soot and radiation. Thus in this study, we overcome this limitation by using the transient flamelet model. Also, for soot formation on laminar non-premixed flame, transient flamelet coupled with two-equation soot model has been adopted due to its inherent advantages in terms of accuracy and availability. Based on numerical results, the detailed discussion has been made for the precise structure and soot formation processes in the pressurized methane air flames.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.137-138
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• 2012

The two-equation soot model based on the transient laminar flamelet model is implemented for soot formation of laminar non-premixed $CH_4/Air$ flame with detailed chemical reaction mechanism and complex thermodynamic properties. The soot model represents nucleation, growth and oxidation with gas-phase chemistry. This represented unsteady flamelet soot model has been tested and compared using well verified reference calculation result obtained solving the Full Transport Equations method.

• Proceedings of the KSME Conference
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• 2001.06d
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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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• 2003.05a
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• pp.195-199
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• 2003

The stoichiometric methan/air premixed turbulent flames at the axisymmetric Bunsen burner situation are numerically investigated. To account for the chemistry-turbulence interaction in the turbulent premixed flames, the steady laminar flamelet library method has been adopted. The flame front is tracked by using the Level-Set Approach. Turbulence is represented by the ${\kappa}-{\varepsilon}$ modeling with a Pope's correction. The detailed comparison between prediction and measurement has made for the flame field in terms of velocity, turbulent kinetic energy, and normarlized temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.150-155
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• 2010

Liquid rocket injectors play crucial roles on propulsive performance, combustion stability, and heat transfer characteristics. Nevertheless, their developments have mainly relied on empirical methods and expensive hot-firing tests due to lack of fundamental understanding of high pressure combustion phenomena in the near-injector regions. The present study was motivated by recent efforts to develop reliable modeling of liquid rocket combustion. The turbulent combustion model based on the flamelet concept has been extended to take into account real-fluid behaviors occurred at supercritical pressures, and validated against measurements for a cryogenic nitrogen injection, a non-premixed turbulent jet flame at atmospheric pressure, and a LOx/$GH_2$ coaxial shear injector at a supercritical pressure.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.24-32
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• 2002

The autoignition and subsequent flame propagation of initially nonpremixed turbulent system have been numerically analyzed. The unsteady flamelet modeling based on the RIF (Representative Interactive Flamelet) concept has been employed to account for the influences of turbulence on these essentially transient combustion processes. In this RIF approach, the partially premixed burning, diffusive combustion and formation of pollutants(NOx, soot) can be consistently modeled by utilizing the comprehensive chemical mechanism. To treat the spatially distributed inhomogeneity of scalar dissipation rate, the multiple RIFs are employed in the framework of EPFM(Eulerian Particle Flamelet Model) approach. Computations are made for the various initial conditions of pressure, temperature, and fuel composition. The present turbulent combustion model reasonably well predicts the essential features of autoignition process in the transient gaseous fuel jets injected into high pressure and temperature environment.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.81-89
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• 2002

The autoignition and subsequent flame propagation of initially nonpremixed turbulent system have been numerically analyzed. The unsteady flamelet modeling based on the RIF (representative interactive flamelet) concept has been employed to account for the influences of turbulence on these essentially transient combustion processes. In this RIF approach, the partially premixed burning, diffusive combustion and formation of pollutants(NOx, soot) can be consistently modeled by utilizing the comprehensive chemical mechanism. To treat the spatially distributed inhomogeneity of scalar dissipation rate, the multiple RIFs are employed in the framework of EPFM(Eulerian particle flamelet model) approach. Computations are made for the various initial conditions of pressure, temperature, and fuel composition. The present turbulent combustion model reasonably well predicts the essential features of autoignition process in the transient gaseous fuel jets injected into high pressure and temperature environment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.237-240
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• 2006

Hybrid propulsion systems provide many advantages in terms of stable operation and safety. However, classical hybrid rocket motors have lower fuel regression rate and combustion efficiency compared to solid propellant rocket motor. Accordingly, the recent research efforts are focused on the improvement of engine efficiency and regressionrate in the hybrid rocket engine. The present study has numerically investigated the combustion processes and the flame structure in the hybrid rocket engine. The turbulent combustion is represented by the flamelet model and Low Reynolds number $k-{\varepsilon}$turbulent model is employed to reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect. Numerical results suggest that the present approach is capable of realistically simulating the combustion characteristics of the hybrid rocket engines.