• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1021-1027
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• 2004

Design performances of various configurations of hybrid systems combining an atmospheric pressure molten carbonate fuel cell and a gas turbine have been analyzed. Two different fuel reforming methods (internal and external reforming) were considered. Influences of turbine inflow heating method, location of fuel combustor and associated component arrangements were investigated. In general, internal reforming leads to higher system efficiencies. The optimum design pressure ratio varies among different system configurations. In particular, the design point selection is closely related to the allowable turbine inlet temperature. Configurations with direct heating of turbine inlet flow may realize both higher efficiency and higher specific power than those with indirect heating.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.81-85
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• 2012

In this paper, the typical combustion instabilities in hybrid rocket were studied. To induce combustion instabilities in the combustor with the diaphragms were mounted, on front and rear of the fuel, and combustion experiments were performed. The calculated theoretical frequencies using Longitudinal Acoustic Mode and Helmholtz Mode are compared with experimental frequencies using FFT analysis. The theoretical calculated results showed good agreements with experimental results are compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.9-15
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• 2012

An unsteady internal ballistic performance model was proposed to take account for the variance of local regression rate along the grain port of a hybrid rocket combustor. The characteristic parameters of hybrid rocket motor was investigated. The performance model of concern in the study was fairly comparable with the test result. The combustion coefficients and local burning characteristics of a hybrid rocket motor were evaluated. The local variation of the oxidizer mass flow rate results in the changes of local regression rate, pressure, temperature, and gas velocity to flow direction, which was analyzed quantitatively.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.51-59
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• 2007

The end-burning combustion field using impinging oxidizer injectors are analyzed with tangential type injectors in order to examine their mixing and combustion characteristics. The impinging type showed further improved mixing effect as well as the combustion efficiency compared to the previously studied tangential injector. A novel injector capable of delivering impinging and swirl effect is introduced in this study where it demonstrated that the grain coning effect can be avoided. It was found that the combined impinging and swirling flow would promote the radial mixing rate increasing the residence time and the turbulent intensity. However, the use of the step combustor which may augment the turbulent intensity did not show any notable difference compared to the basic combustor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.526-529
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• 2009

In this study, we analyze the characteristic of burning classified by a propellant according to a flux of an oxidizer to analyze propellant regression distance in accordance with a thrust control and burning time of hybrid rocket using hybrid combustor of Lab-Scale. To control a flux of an oxidizer, we design flow control system to regulate the mount of opening and shutting of a needle valve by a driving of stepping motor by a combination the needle valve with stepping motor. We derive the relationships between mass flow rate and regression rate according to a propellant through the oxidizer flux change. While doing the thrust control, we estimate regression distance through the oxidizer flux in accordance with thrust and confirm the creditability through the actual thrust control burning experimentation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.511-518
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• 1986

본 연구에서는 난류모델로는 기존의 K-.epsilon.모델과 LPS방법으로 수정된 K-.epsilon. 모 델을, 수치적 Scheme으로는 Hybrid Difference Scheme과 Skew-upwind Difference Sc- heme을 사용하여 그 결과를 각각 비교하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.163-166
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• 2012

The hybrid combustion were performed with the different diaphragm position for the experimental studies on characteristic of regression rate and combustion efficiency. The diaphragm was installed in 25% and 50% of fuel length from the front of solid fuel, respectively. As results of experiments, the position of diaphragm has small effect on the regression rate and combustion efficiency. It is considered that the diaphragm has local effect near the diaphragm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.745-751
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• 2012

Hybrid rocket shows interesting characteristics of complicated mixing layers developed by interactions between turbulent oxidizer flow and mass flow from surface due to fuel vaporization. In this study, compressible LES with a ring structure attached at the entrance of the combustor are performed. According to one recent report, adding a ring structure in the middle of the combustor helps increasing regression rate. From the numerical results, it is seen that vortex structures near the wall becomes stronger due to the interaction with surface mass injection, and the local heat flux increases due to the vortices. This phenomenon is obviously related to the generation of dimple structures which are seen in the number of experiments. Also, the ring structure at the entrance induces strong vortex flow which enhances heat transfer to the wall surface and mixing between fuel and oxidizer as well as reaction efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.517-521
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• 2009

A unsteady internal ballistic analysis model was proposed to take account for the variance of local variance of pressure and velocity along the grain surface of a hybrid rocket combustor. The model of concern in the study was fairly comparable with the test result. The local variation of the oxidizer mass flow rate along grain surface results in chamber pressure, regression rate, and gas velocity change along its flow direction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.180-185
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• 2004

Our previous study showed that although the hybrid rocket engine with swirling gaseous oxygen had high performance, a direct injection of LOX with swirl into the combustion chamber of the hybrid rocket engine lowered the performance of the engine, compared to that with gaseous oxygen. In order to clarify this reason, combustion tests of a small PMMA combustor with an inner port diameter of 2 mm were conducted in liquid oxygen flow by comparison with gaseous oxygen flow. Although the oxygen mass fluxes of LOX were about two orders of magnitude larger than those of gaseous oxygen, the fuel regression rate of LOX were remarkably smaller than those of gaseous oxygen. For both liquid and gaseous oxygen, diffusion flames in the port of the grain controlled the combustion process of PMMA in oxygen flow. These results may be explained by the fact that only small amount of LOX vaporized and consumed in the combustion with PMMA while flowing through the port due to relatively larger latent heat of injected liquid oxygen compared to the heat of release by combustion which depended on the burning surface area of PMMA.