• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.371-376
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• 2007

Pan and rayon materials, two types of carbon fabric/phenolics composites, are using as thermal protectors for SRM's nozzle. After burning tests, It was required to analyze the performance of nozzles by ablated shape because ablative patterns were different from each other. For studying of performance on supersonic nozzles that have ablated shape, 1-dimensional analysis and numerical analysis were performed and results were presented in this paper. As the results of this study, in case of the thrust loss, rayon was predicted about 0.53% higher than pan and in case of total impulse loss, rayon was predicted about 0.4% higher than pan.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.230-237
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• 2012

The ultrasonic resonance method was applied to detect the disbond interface and empty layer between steel and FRP of the exit cone. The ultrasonic resonance method can easily detect the disbond interface and empty layer by amplifying the ultrasonic signal, but pulse echo method is difficult to distinguish adhesive interface from disbond interface or empty layer. The resonance frequency was predicted using the pressure reflection coefficient of 3-layered medium, and measured from ultrasonic signal of the test block using Fast Fourier Transform. The ultrasonic resonance proved that the predicted resonance frequency was in good agreement with the measured resonance frequency.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.33-40
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• 2020

A sturdy on the adhesion properties of solid propellants, liners, and insulation was carried out according to the types of barrier coats. A barrier coats were used to prevent migration of the plasticizer or curative between the propellant/liner/insulation, and the barrier coat was selected out of Isocyanates with different molecular weight and number of -NCO in one molecule. As a result, it was found that the more the -NCO group and the larger molecular weight, the stronger adhesion. In addition, as a result of experiments about effects of the pot life after applying the barrier coat on bond strength, the adhesion strength was shown to increase as the pot life was short.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.1
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• pp.11-19
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• 2001

기능경사재(FGM)는 구성 물질의 체적분율(volume fraction)이 복합재 전체에 걸쳐 연속적 그리고 기능적으로 분포되어 있어, 기존의 이종물질 접합식(bi-material-type) 복합재보다 현저히 우수한 열기계적 특성을 가진다. 하지만, 기능경사 내열복합재의 열-탄소성 거동은 체적분율의 분포형태와 경사층이 차지하는 상대두께비에 따라 절대적으로 좌우된다. 본 연구는 기능경사 내열복합재의 열-탄소성 특성의 이들 두 설계인자에 대한 파라메트릭 FEM해석을 다룬 것이다. 열-탄소성 이론과 유한요소 근사화에 따라 연구용 2차원 FEM 프로그램을 개발하고, 대표적인 3층 구조의 2차원 기능경사 내열복합재의 열-탄소성 특성을 설계변수의 다양한 조합에 따라 분석하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.59-71
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• 2019

The numerical analysis of ablative thermal protection systems (TPS) for solid rockets has been carried out with various in-house codes since the 1960s. However, the application scope of commercial codes has been expanded by adding subroutines and user-defined functions (UDF) to codes such as Fluent, Marc, and ABAQUS. In the past, the flow, thermal response and structural analysis of TPS have been performed using separate approaches. Recently, research has been conducted to interrelate them. In this paper, the thermal response characteristics of thermal protection materials, the in-house codes for thermal response analysis, and the research trends of flow-thermal-structure analysis of TPS using commercial codes were reviewed.

• Defense and Technology
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• no.10 s.164
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• pp.30-31
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• 1992

• Composites Research
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• v.15 no.1
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• pp.53-60
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• 2002

Composite ablative tubes required capabilities of ablative and structural characteristics were fabricated through filament winding technique and several experiments were conducted to evaluate the structural performance of composite ablative tubes. For this purpose, manufacturing procedures were briefly described and then resin digestion method was applied to measure the fiber volume fraction and the void content of composite ablative tubes. The configuration of tensile specimen fur composite ablative tubes with not losing the continuity of reinforced fibers was suggested by evaluating mechanical properties of several types of the specimen with different widths. Also, suitable processing variables for composite ablative tubes were determined by evaluating mechanical properties of several types of the specimen with different processing variables. In addition, acoustic emission signals were obtained during the proof test and could be applicable to study the crack initiation and the damage mode of composite ablative tubes. Finally, the structural reliability of composite ablative tubes could be verified to satisfy design requirements through the proof and burst tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.68-77
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• 2019

C/SiC composites were developed by a liquid silicon infiltration(LSI) method for use as heat-resistant parts of solid and liquid rocket propulsion engines. The heat resistance characteristics according to the composition ratio (carbon / silicon / silicon carbide) were evaluated by specimen test through arc plasma, supersonic torch test. An ablation equation for oxidation reactions was presented. Through the combustion test it was verified that various parts such as nozzle insert, exit cone and combustion chamber heat resistant parts for rocket propulsion can be manufactured and proved high ablation performance and thermal structure performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1282-1291
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• 1989

본 연구에서는 이러한 연구의 시작단계로 노즐내의 열 경계층 방정식을 정리하고 압축성 와점도모델을 도입하여 유한 차분법을 이용한 전산프로그램을 작성 하였다. 한편 실제로 추진모테에서는 고온 고속의 열기류가 분출되기 때문에 추진 하고 있는 동안 노즐벽을 형성하고 있는 내열재가 심하게 손상되어 표면의 상태가 매우 거칠게 된다. 더구나 경우에 따라서는 내열재가 용발(ablation)하게 된다. 이러한 상태를 감안하여 마찰계수와 열전달 계수를 합리적으로 추정해야만 노즐의 설계와 주변장치를 합리적으로 수행할 수 있다. 따라서 본 연구에는 주로 경계층 내의 압력구배, 압축성의 효과, 물성치의 변화를 고려한 기존 난류모델에 근거하여 프로그램을 작성하고, 이것을 토대로 노즐표면 조도의 영향 및 분출(blowing)의 영 향을 중점적으로 고려하여 그 특성을 연구하였다. 노즐벽에서 분출을 고려한 이유는 표면이 용발할 때 표면의 온도가 거의 일정하게 유지된 상태로 노즐표면이 화학작용을 수반하면서 가스화됨을 초보적으로 고려해보기 위함이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.305-308
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• 2005

This paper presents a fabrication of a full-stale combustion chamber of a liquid rocket engine for a ground hot firing test. Engine drawings for manufacturing were prepared after conceptual and detail designs. The combustor is composed of a head and a chamber. SUS316L is used for materials of the head because of the good quality in low temperature. Inner materials of the ablative cooling chamber is silica/phenolic and outer case materials is the SUS316L. Materials of the regenerative cooling chamber are C18200 and SUS316L. After lathe, general milling and MCT machinings, components were finished by electrolytic polishing. A brazing method was applied for bonding the injectors and the injector plate, the regenerative cooling chamber because of structure configurations.