• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.233-239
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• 2003

The present study has numerically investigated the combustion processes in the solid propellant rocket engine. The two step global reaction model for condensed phase and five step global reaction mechanism for gas phase are adopted to predict the detailed flame structure near double-base solid propellant surface. The turbulence-chemistry interaction is represented by the PaSR(Partially Stirred Reactor) model. To reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect, the Low Reynolds number k-$\varepsilon$ turbulent model is employed. Based on numerical results, the detailed discussion has been made for the turbulent combustion processes and transient behavior of pressure and temperature fields in the solid propellant rocket engine.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.105-112
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• 1996

A linear acoustic analysis for baffled rocket combustion chambers has been developed. This study provides the comprehensive theoretical background for the baffle as one of the stabilizing devices in a liquid rocket propulsion system. Several specific effects of baffles are presented as mechanisms by which baffles eliminate instability. Included are longitudinalization of transverse waves inside baffle compartments, severe restriction of velocity fluctuations near the injector face, and decreased normal mode frequency of the chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.267-273
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• 2004

This paper targets to define controlling factors of pressure-coupled combustion response and estimate their effects on droplet evaporation process. Dynamic characteristics of hydrocarbon propellant vaporization perturbed by acoustic pressure are numerically simulated and analyzed. 1-D droplet model including phase equilibrium between two phases is applied and acoustic wave is expressed by harmonic function. Effects of various design factors and acoustic pressure on combustion response are investigated with parametric studies. Results show that driving frequency of acoustic perturbation and ambient pressure have important roles in determining magnitude and phase of combustion response. On the other hand, other parameters such as gas temperature, initial droplet size and temperature, and amplitude of acoustic wave cause only minor changes to magnitude of combustion response. Resultant changes in phase of heat of vaporization and thermal wave in droplet highly influence magnitude and phase of combustion response.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.43-49
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• 2014

This experimental study has been conducted to scrutinize the effects of an ultrasonic standing wave (USW) on the propagating velocity and structure of methane/air premixed flame. Propagating flame was caught by high-speed Schlieren photography, and the variation of flame-behavior was analyzed in detail. It is revealed that horizontal splitting in burnt zone is resulted by the USW, and the flame propagation velocity is augmented due to the strengthened chemical reaction. Evolutionary feature of the flame perturbed by USW, maintaining a pseudo-symmetry of top and bottom flame-front about the propagation axis tends to be free from buoyancy effect.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.548-553
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• 2011

The device for studying combustion characteristic of aluminum powder and water was developed. The device has ability to adjust temperature, pressure, and equivalent ratio to some specified value which effect on combustion characteristic of aluminum and water mixture. Methane combustor, water supply device, aluminum powder feeder, and linear combustor are assembled to aluminum combustion test device. Each device has the ability to supply matter to combustor on steady and quantitatively controlled manner and test sequence specified by user can be automatically controlled. The combustion of aluminum powder was observed when integrated device was operated normally.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.6
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• pp.34-40
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• 2009

The present study describes the methods and standards for the combustion stability assessment of a thrust chamber and a gas generator as parts of a liquid rocket engine. The first method uses a statistical approach through typical static combustion tests and the second one a dynamic assessment identifying decaying characteristics of pressure fluctuations excited by a pulse generating device. Based on accumulated test results, it is concluded that the maximal values for combustion stability are 3% of a chamber static pressure with a Root-Mean-Square value of pressure fluctuations, and 10 msec with a decay time.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.318-323
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• 2012

This study is conducted to scrutinize agitation effects of an ultrasonic standing wave on the dynamic behavior of methane/air premixed flame. The propagating flame is caught by high-speed schlieren images, through which flame front and local flame velocity are analyzed and obtained, too. It is revealed that the propagation velocity with ultrasonic standing wave is larger than the case without excitation except around the flammability limits. Also, vertical locations of distortions and depth of dents of the front are constant, unless the ultrasonic standing wave characteristics are not changed.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.16-23
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• 2013

An experimental study has been conducted to investigate the effects of equivalence ratio on the propagation characteristics of $CH_4$-air premixed flame intervened by an ultrasonic standing wave. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in detail throughout the post-processing analysis. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancement of combustion reaction and flame propagation velocity. Effectiveness of the standing wave on the flame velocity decreases as the equivalence ratio increases. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratios.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.60-67
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• 2022

A study was conducted to analyze the behavioral change of the kerosene flame ultrasonically-atomized under an ultrasonic standing-wave. Combustion region was visualized through DSLR, ICCD camera and the Schlieren photography with high-speed camera. The fuel consumption was measured by a precise scale. As a result, in the case of ultrasonic standing-wave excitation, it was observed that the intensity of OH radical(OH^*) was enhanced and optimal combustion condition was formed around the upper edge of the standing-wave field.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.155-160
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• 2002

연소시 발생하는 오염물질 중 NOx는 심각한 대기오염의 원인이 되는 것으로 알려져 있어, 각종 연소기 등에서 발생하는 NOx 저감을 위한 연구가 중요하게 대두되었다. 특히 확산화염은 예혼합화염 및 부분예혼합화염에 비해 NOx, Soot 등 오염물질이 발생할 가능성은 높으나 화염 안정성이 좋아 산업용 연소기에 많이 이용되고 있어 보다 다양한 NOx 저감 기술의 필요가 요구되고 있다.(중략)