• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.35-35
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• 1998

고체 로켓 추진기관의 노즐을 개발하기 위해서는 주어진 체계 제한 조건내에서 기본적인 가스의 동력학, 내탄도에 의한 형상 설계, 재료 개발 및 적용 기술, 열전달 계산에 의한 열설계 및 해석 등이 종합적으로 적용되며 수많은 반복과정을 거쳐야 한다. 특히 최근에는 알루미늄 함유량을 증가시켜 연소가스의 온도가 300$0^{\circ}C$ 이상이 되는 고성능 추진제가 일반적으로 적용되고 있으므로 고온에 의한 열적문제가 심각하게 대두되고 있으며 이에 견디는 신뢰도가 높은 노즐 설계개발이 요구되고 있다. 노즐목을 노즐내에서 열부하가 가장 심한 곳으로 노즐목 확대에 의한 추력 손실을 최소화하기 위해 내삭마성이 강한 재료를 선정하여야 하며, 그래파이트는 이러한 조건을 만족시키는 소재의 하나로 많이 적용되고 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.379-382
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• 2017

Flow characteristics of dual bell nozzle with pintle were investigated. Thrust and thrust coefficient were compared with the pintle-bell nozzle of the same condition, and difference according to the pintle stroke was investigated. At stroke 0 mm, the thrust of the dual bell nozzle was about 13.18% higher than the bell nozzle, and when the pintle was backward, it was similar to the bell nozzle. The change in expansion ratio with stroke was considered to be more advantageous for a dual bell nozzle that performs altitude compensation through separation and transition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.13-13
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• 1999

본 논문에서는 해석영역의 형상변화, 즉 로켓노즐 내열재의 삭마로 인해 야기된 경계 면의 이동을 고려하면서 2차원 비정상 비등방성 재료의 열전달 문제를 해석할 수 있는 수치해석에 대해 기술하였다. 수치해석 알고리즘은 유한요소법이며 열해석시 경계면 이동으로 인한 격자계의 절점 좌표점이 계산과정 동안에 이동하는 변형 가능한 유한요소격자(transformable finite-element grid)를 사용하였다. 본 수치해석기법의 타당성 입증을 위해 극심한 열하중이 부여된 조건하에서 엄밀해가 존재하는 비정상 축대칭문제 및 고체로켓 노즐내열재에 대해 열해석을 수행하였으며, 그 결과 수치해는 엄밀해 또는 실험치와 잘 일치함을 보이었다. 여러 가지 복합재로 구성된 내삽노즐 또는 외삽노즐에 대해서도 안정된 수치해를 얻을 수 있었다. 아울러 노즐목삽입재로 탄소-탄소 복합재를 적용한 고체추진기관 내삽노즐을 해석모델로 택하여 열전달 해석을 수행하고 해석결과를 분석하였다. 노즐의 표면산화반응에 대한 열반응상수, 즉 Arrhenius 형태로 표시된 식에서 pre-exponential factor 및 activation energy 변화가 탄소-탄소 복합재 및 탄소-페놀릭 복합재의 삭마량에 미치는 영향에 대해서 고찰하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.495-499
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• 2005

The INHA Rocket Research Institute changed the Ceramic nozzle material of their developed Solid Composite Propellant Motor with Teflon nozzle material. Static firings of the new Solid Rocket Motors was conducted on Thurst Tester to validate the increase in performance. The new enhanced Solid Roket Motor increased the total impulse by 18.3 percent while improving its reliability. The new process of manufacture reduced the time to produce a nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.32-32
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• 2000

3단형 과학로켓의 고체모타의 내부 유동을 추진제의 연소에 따라 내부형상이 변화하는 과정에 대해 수치해석 하였다. 추진제는 표면에서 균일하게 연소된다고 가정하였으며 연소거리가 0.1mm, 30mm, 60mm, 90mm인 경우의 고체모타 내부 물리량 변화를 관찰하였다. 연소가 진행되며 잠입형 노즐의 위 부분에 큰 재순환 영역이 생기는 것이 관찰되었으며 노즐에 작용하는 압력 힘을 구하여 본 결과 노즐부의 모멘트 힘은 크지 않은 것으로 판명되었다.(중략)

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.8-14
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• 2008

Solid Rocket Motor(SRM) has advantages such as - high specific impulse, operational safety and simplicity in design and manufacturing process but thrust magnitude can't be controlled. For studying of pintle nozzle that can control the thrust magnitude of SRM, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, pintle tip's shape and nozzle contour were important design parameters because thrust performance and variable thrust range of pintle nozzle depend on them. Especially, the thrust of needle typed pintle nozzle adopted in this test was predicted 13% higher than normal nozzle without pintle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.289-294
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• 2007

Solid Rocket Motor(SRM) has advantages such as - high specific impulse, operational safety and simplicity in design and manufacturing process, but thrust magnitude can't be controlled. For studying of pintle nozzle that can control the thrust magnitude of SRM, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, pintle tip's shape and nozzle contour were important design parameters because thrust performance and variable thrust range of pintle nozzle depend on them. Especially, the thrust of needle typed pintle nozzle adopted in this test was predicted 13% higher than normal nozzle without pintle.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.70-77
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• 2000

Supersonic Dual Bell Nozzle (SDBN) is an altitude-adaptive propulsion nozzle achieved only by a nozzle wall inflection. In order to investigate the altitude adaptive capability and the effectiveness of this nozzle concept, the present study addresses a computational work of the flow through SDBN. Several types of the SDBNs are tested for a wide range of the pressure ratio which covers from an over-expended flow to a fully under-expended flow at the exit of the SDBN. Axisymmetric, compressible, Wavier-Stokes equations are numerically solved using a fully implicit finite volume differencing scheme. The present computational results reveal that the base nozzle length affects the shock wave system occurring inside SDBN. For a quit wide range of the pressure ratio the flow separation occurs at the nozzle inflection point. It is found that the maximum thrust coefficient is obtainable for the correct expansion state at the exit of SDBN.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.497-500
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• 2011

The experimental study of thermal stress in the solid rocket engine nozzle with two different materials, SCM-440 and STS-630, was evaluated. SCM-440 has lager temperature increasing rate and higher temperature at the nozzle expansion region than STS-630. Thermal barrier efficiency and endurance of Zirconia coating were evaluated after making two more nozzles coated by Zirconica. Both coated materials showed about 70 percent higher thermal barrier efficiency than uncoated nozzles. Therefore, Zirconia coating using plasma spray method was useful in thermal safety at supersonic nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.487-490
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• 2005

The thrust Control in Solid Propellant Rocket is incomparably limited than that in Liquid Propellant Rocket. Because it is fixed that section to relate a combustion, that is a natural result. The control of a thrust directions in a Solid Propellant Rocket is not efficient for the purpose of a Solid Propellant Rocket. But it is a problem to solve that a weight on board should increase through the maximization of the thrust in a Solid Propellant Rocket.