• Defense and Technology
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• no.12 s.178
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• pp.64-69
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• 1993

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.153-161
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• 2004

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.115-116
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• 2015

In the present approach, the flame-acoustics interaction is represented by FDF (Flame Describing Function) which is a important source term in the Helmholtz' equation. In this study, the combustion instability is analyzed by the forced mode strategy with the measured FDF. Numerical results indicate that the present approach reasonably well predicts the essential features of the combustion instability characteristics in the lean premixed combustor under the gas-turbine like environment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.303-306
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• 2011

An experimental study has been conducted to investigate the effects of an ultrasonic standing-wave field to the behavior of methane/air premixed flame. Visualization technique utilizing the schlieren method was employed for the observation of premixed flame behavior. The shape of flame front and local flame velocity were measured according to the variation of reactants pressure and chamber opening/closing condition. The flame front was distorted and severely deformed to a lotus-type flame by the interaction of ultrasonic standing-wave and the reflection wave coming from an end wall of reactor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.750-756
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• 2002

The effect of equivalence ratio and velocity on the stability of flame in dump combustor was studied in an atmospheric pressure, laboratory scathe dump combustor operating natural gas. Traditionally, peak-to-peak pressure, fluctuation of the heat release rate and Rayleigh index were used to find and control the combustion instability. Cross correlation coefficients, Ci,j which is defined as the normalized value of the integration of the product of two of the mixer pressure, dump plane pressure and heat release rate, are introduced to see whether the flame is stable or not. Ci,j shows more sensitive to combustion status than Rayleigh index in steadily burning flame. Also, the result indicates that the amplitude of Ci,j between heat release and mixer pressure goes up before the flame at the rich de-stabilizing equivalence ratio near $\psi$=0.85. t means Ci:j at this case has a potential to detect the de-stablizing moment in prior to becoming unstable in dump combustor.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.27-36
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• 2013

Linear stability analysis for combustion instability within a cylindrical port of solid rocket motor has been conducted. The analysis of acoustic energy has been performed by a commercial COMSOL code to obtain the mode function associated to each acoustic mode prior to the calculation of stability alpha. An instability diagnosis based on the linear stability analysis of Culick is performed where special interests have been focused on 5 stability factors(alpha) such as pressure coupling, nozzle damping, particle damping and additionally, flow turning effect and viscous damping to take into account the flow and viscosity effect near the fuel surface. The instability decay characteristics depending on the particle size is also analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.262-265
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• 2003

This Study is focused on the instrumenting Hybrid Rocket Motor of ACPL at Konkuk University and researching combustion instability by measuring regression rate versus oxidizer mass flux. In the result of experiment, test fire was moderate and we could acquire data of pressure, thrust, and temperature of combustion chamber. In the future, studying unsteady change of regression rate and pressure characteristic analysis of combustion chamber through hundreds of experiments should be performed. furthermore, researching characteristic velocity by taking a measurement of combustion temperature will be inevitable.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.60-67
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• 2019

To understand the low frequency instability(LFI) characteristics in hybrid rockets combustion, effects of equivalence ratio variations on the phase shift between pressure and heat release oscillations were investigated by using the direct numerical simulation. The change in the equivalence ratio of the main chamber was simulated by the temperature and composition variation of the combustion gas introduced into the post-combustion chamber. In the results, additional combustion appeared along with vortex generation at the backward step, and combustion pressure and heat release oscillations were observed as the vortex moved. In addition, the results confirmed that the phase difference between the pressure and heat release oscillation shifts because of the changes in the propagation velocity of pressure wave as the temperature of combustion gas changes.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.71-84
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• 2007

The review of the liquid propellant rocket engine is presented. The combustion instabilities which were discovered on solid and liquid propellant rocket engines in 1930, have occurred on propulsion devices, such as gas turbine, ramjet, scramjet and rocket, and thus a study on the combustion instability became necessary. However, this problem has not been solved yet. Therefore, we investigated causes and mechanisms of the combustion instability and surveyed the efforts of solving combustion instability in various countries for developing stable liquid propellant rocket engines.

• Journal of KSNVE
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• v.14 no.4
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• pp.16-28
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• 2004

항공우주산업은 항공기나 우주비행체를 생산하는 모든 관련 산업으로 정의할 수 있다. 소음진동측면에서 보면 항공기는 운송수단의 하나로 사용되므로 소음 관련 규제 법률에 따라서 관련기술의 발전이 이루어져 왔다고 볼 수 있으나 우주비행체는 운행공간을 고려 할 때 소음진동기술이 작동효율성 (연소불안정성, 공진파괴 등)을 향상시키기 위한 기술로 사용되어 왔고 그 범위도 매우 제한되어 있다. 따라서 소음진동기술은 주로 항공기 분야에서 많은 응용을 구하고 있는 실정이다. (중략)