• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.189-193
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• 2005

Thermal effect of finite-rate chemistry on linear combustion stability and film cooling effect are investigated in sample rocket engine. The flow variables required to evaluate stability limits are obtained from CFD data with finite-rate chemistry adopted in three dimensional chamber. Major flow variables are affected appreciably by finite-rate chemistry and thereby, the calculated stability limits are modified. It is found that finite-rate chemistry contributes to stability enhancement in thermal point of view. And film cooling also has the effect of combustion stabilization.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.75-81
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• 2006

Thermal effect of finite-rate chemistry on linear combustion stability and film-cooling effect are investigated in sample rocket engines. The flow variables required to evaluate stability limits are obtained from CFD data with finite-rate chemistry adopted in three dimensional chamber. Major flow variables are affected appreciably by finite--rate chemistry and thereby, the calculated stability limits are modified. It is found that finite-rate chemistry contributes to stability enhancement in thermal point of view. And film cooling also has the effect of combustion stabilization.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.37.2-37.2
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• 2005

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.114-123
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• 2002

A supersonic rocket plum flowfield of kerosene/liquid-oxygen based propulsion system has been analysed using the Reynolds-averaged Navier-Stokes equations coupled with a 9-species 14-reaction finite-chemistry model. The result were compared with chemically frozen flow solution to investigate the effect of finite-rate chemistry on the plume flowfield. The computations were performed using a commercial CFD software, FLUENT 5. The finite-rate chemistry solution exhibited higher temperature caused by the reactions within the nozzle. All the chemical reactions within the plum were dominated only in the shear layer and behind the barrel shock reflection region where the temperatures are high and the effect of finite-rate chemical reactions on the flowfield was found to be insignificant. However, the present plume computation including the finite-rate chemical reaction within the plume has revealed major reactions occurring in the plum and their reaction mechanisms.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.401-405
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• 2010

An efficient performance model for scramjet engines has been proposed for scramjet performance design. In supersonic air intake design, the compression angles of the wedge were determined to maximize the total pressure recovery of the intake based on Oswatisch criterion. Both combustion models of chemical equilibrium and finite-rate chemistry model are implemented, and compared each model with the results by Starkey for Waverider engine configuration. Finally, the performance model of concern has been confirmed by conducting performance analysis with hypothetical mission profile and design conditions.

• Journal of the Korean Society of Combustion
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• v.6 no.2
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• pp.15-22
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• 2001

A pressure-based, unstructured finite volume method has been applied to couple the chemical kinetics and fluid dynamics and to capture effectively and accurately the steep gradient flame field. The pressure-velocity coupling is handled by two methodologies including the pressure-correction algorithm and the projection scheme. A stiff, operator-split projection scheme for the detailed nonequilibrium chemistry has been employed to treat the stiff reaction source terms. The conservative form of the governing equations are integrated over a cell-centered control volume with collocated storage for all transport variables. Computations using detailed chemistry and variable transport properties were performed for two laminar reacting flows: a counterflow hydrogen-air diffusion flame and a lifted methane-air triple flame. Numerical results favorably agree with measurements in terms of the detailed flame structure.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.692-698
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• 1991

The reaction path Smoluchowski equation approach developed in a recent work to calculate the rate constant for a diffusive multidimensional barrier crossing process is extended to incorporate the configuration-dependent diffusion matrix. The resulting formalism is then applied to the investigation of stilbene photoisomerization dynamics. Adapting a model two-dimensional potential and a model diffusion matrix proposed by Agmon and Kosloff [J. Phys. Chem.,91 (1987) 1988], we derive an eigenvalue equlation for the relaxation rate constant of the stilbene photoisomerization. This eigenvalue equation is solved numerically by using the finite element method. The advantages and limitations of the present method are discussed.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.92-97
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• 2007

Numerical simulations were carried out to investigate the base drag characteristics of a base bleed projectile with a central propulsive jet by considering the base burning process. Overall fluid dynamic process is modeled by Navier-Stokes equations for reacting flows with two-equation $k-{\omega}$ SST turbulence closure. The combustion process is modeled by finite-rate chemistry with a given partially burned exit condition of the BBU (base-bleed unit). Besides the demonstrating the capability of the present CFD solver for the base drag and the interaction of the base flow with a rocket plume, present study gives an insight into the fluid dynamics and the combustion process of the hybrid-propulsion projectile.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.569-574
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• 1991

Methyl red diffusion in polymer solutions was studied by a transient holographic method, forced Rayleigh scattering. In semi-dilute solutions of a polystyrene, where no specific interaction with the probe exists, we found within experimental uncertainty that the retardation of diffusion rate of methyl red is independent of the solvents used. This indicates that the hydrodynamic interaction in polymer coils is not affected by the nature of solvents enough to exhibit a detectable change in the diffusion rate of the probe. On the other hand, a substantial reduction of diffusion rate was observed in poly(methyl methacrylate) solutions in toluene. Together with the similar observation reported with poly(vinyl acetate), it is confirmed that hydrogen bond between the probe and the polymer is responsible for the retarded diffusion. The decay-growth-decay profile found in this system reveals a finite difference in diffusion coefficients of cis and trans isomer of methyl red. We estimate the difference and suggest that the cis isomer interacts with the polymer more strongly than the trans isomer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.327-330
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• 2006

Numerical simulations were carried out to investigate the base drag characteristics of a base bleed projectile with a central propulsive jet by considering the base homing process. Overall fluid dynamic process is modeled by Wavier-Stokes equations for reacting flows with two-equation $k-\omega$ SST turbulence closure. The combustion process is modeled by finite-rate chemistry with a given partially burned exit condition of the BBU (base-bleed unit). Besides the demonstrating the capability of the present CFD solver for the base drag and the interaction of the base flow with a rocket plume, present study gives an insight into the fluid dynamics and the combustion process of the hybrid-propulsion projectile.