• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.24-25
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• 2000

실제 추진기관에서 비추력 성능에 미치는 열/유동현상은 이상 유동(ideal flow)과는 달리, 추진기관의 특성에 따라 다양한 열/유동손실이 나타나며, 연소시험 시에는 이러한 성능 손실 인자들이 복합적으로 작용하여 나타나는 추력이 측정된다. 따라서 임의의 추진기관을 새롭게 성능 설계할 때에 부딪히는 문제중의 하나는 추력 손실 양을 정량화 시키는 일이다. 그런데 고체 추진기관은 복잡한 물리적인 현상들이 복합되어 작동되기 때문에 lump parameter로 간단히 추력 손실을 예측하는 것은 매우 어려운 일이다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1108-1111
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• 2017

The nozzle exit shape is scarfed according to the external shape of missile when the nozzle axis should be canted from missile axis due to missile system application. There is inevitable thrust loss for the scarfed nozzle comparing to non-scarfed nozzle. The numerical analysis is necessary to calculate the thrust loss in design process, and ground tests of rocket motor were performed to verify the calculation results. From the comparison of non-scarfed nozzle and scarfed nozzle experiment results, the thrust loss from calculation was about 16.6% and that from experiments was about 15.0%.

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.3 s.153
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• pp.238-247
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• 2007

This paper presents the thrust loss suppression algorithm in the electric propulsion ship. The thrust loss due to cavitation can be regarded as the disturbance torque. The disturbance torque is estimated by means of the disturbance observer. Considering the estimated disturbance torque, the speed reference of the propeller is modified to suppress the thrust loss. The experimental results which performed in the cavitation tunnel with electric machine operating system and its controller will be shown to verify the proposed algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.72-78
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• 2005

We conducted the performance test of micronozzle having nozzle throat diameter of 1.0, 0.5, 0.25 mm in an ambient pressure. We used N2 gas as a cold gas propellant. We varied chamber pressure from 2 to 20 bar and measured the thrust and mass flow rate. Through the test, we concluded that viscous losses were increased with decreasing chamber pressure. We found that micronozzle performance was higher than orifice performance through thrust comparison.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.1-7
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• 2017

The performance of a MEMS solid propellant thruster was predicted and analyzed through internal ballistics model and CFD analysis. The nozzle throat was $416{\mu}m$, and the area ratio of the nozzle was 1.85. As a result of the internal ballistics model, chamber pressure increased up to 197 bar and the maximum thrust was 3,836 mN. In CFD analysis, the chamber pressure of the internal ballistics model was applied as the operating pressure, and the CFD model was divided into an adiabatic and a heat loss model. As a result, the maximum thrust of the adiabatic model was 14.92% lower than that of the internal ballistics model, and the effect of heat loss was insignificant.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.934-939
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• 2007

Thrust vector control(TVC) is the method which generates the side force and moment by controlling the exhausting gas directly from the supersonic nozzle to change the trajectory of a missile quickly. In this paper, performance study on the tapered ramp tabs asymmetrically installed in the supersonic nozzle exhaust for the thurst vector control has been carried out using the supersonic cold flow system. To study the shock wave structure and location of the oblique shock wave produced by the ramp tab, the flow field visualization using the schlieren system is conducted. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.215-218
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• 2007

Internal Ballistic modeling and performance prediction for solid propellant micro thruster was performed with heat loss to the chamber wall as an important factor of miniaturization. Simple l-D end-burner type thruster and general HTPB-AP type composite propellant were selected for computation model. The results showed that the performance loss with the heat loss to the surroundings becomes larger as the surface-to-volume ratio is increased. In this case, the total impulse was reduced about 3% of the case in adiabatic condition.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.368-372
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• 2011

The aerodynamic characteristics of the L-type side jet thruster are examined by using computational fluid dynamics methods. The critical design points of L-type side jet thruster with bent nozzle by 90degrees are studied in terms of the relation between side jet nozzle geometry and thrust efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.202-202
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• 2016

홀 플라즈마 엔진은 인공위성의 궤도유지 및 자세제어 등의 임무수행이나 우주선의 심우주 활용에 있어 필수적인 핵심 우주 부품이다. 홀추력기 연구개발의 최근 큰 관심사는 추력기의 장시간 운전성 확보 및 방전효율 향상이다. 최근 고리형 홀추력기에서 방전 영역 내 플라즈마와 유전체 벽 간의 충돌을 줄임으로써 전극 손상 및 전자온도 손실을 감소시키기 위한 연구가 활발히 진행되고 있다. 특히 전자석 코일을 활용해 방전 채널 벽면과 평행한 방향의 자기장을 형성하여 플라즈마와 유전체 벽 간의 상호작용을 감소시키는 연구들이 소개되고 있으며, 이러한 방법을 자기차폐(magnetic shielding)라 한다. 본 연구에서는 자기차폐 개념이 적용된 방전 소모전력 500 W급 고리형 홀추력기의 방전 및 추력 발생 특성을 연구하였다. 자기장구조 제어를 통해 유전체 벽과 플라즈마 간 상호작용을 감소시킨 결과, 500 V 수준의 방전 전압에서도 유전체 벽에서의 이차전자 발생에 의한 방전전류의 급격한 증가없이 안정적인 방전이 가능하였으며, 이러한 방전 형태는 기존의 자기차폐 개념이 적용되지 않은 일반 고리형 홀 추력기에서 구현하기 어려운 방전 상태이다. 추력기의 자기장 구조 최적화 조건에서 제논 가스 방전을 통해 얻은 최대 추력은 $22{\pm}1mN$, 비추력 $2200{\pm}70s$, 양극효율 $51{\pm}2%$로 매우 우수한 성능을 보여 주었다