• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.265-272
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• 1999

A thrusters modulation method is suggested for spacecraft attitude control with asymmetric configured thrusters during orbit adjustment maneuvers. Attitude is controlled by thrusters off-modulation during orbit maneuvers. Usual control method for symmetric configured thrusters cam not be applied for asymmetric configured thrusters. Disturbance induced from thrusters asymmetricity shall be compensated during pulsing. In this paper, a thrusters control method using null solution is suggested, which is shown working well without inducing disturbance.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.44-53
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• 2022

The depressurization rate in a thrust variable solid rocket motor is the major factor that has the greatest influence on the thrust termination performance. In this study, the depressurization rates range of model solid rocket motor was identified and major factors affecting the depressurization rate were found. It is important for actual system design to understand the depressurization rate of the system that can satisfy the target performance as well as the extinguishing characteristics of the solid propellant. The methodology for obtaining the depressurization rate model in this study is considered to be applicable to the optimal design of the thrust terminable propulsion system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.616-617
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• 2010

Nemerical analysis was carried out for a patented SNECMA modulatable thrust device. By adopting aerospike-like nozzle and a moving needle, proposed modulatable thrust device are capable of delivering optimal thrust according to the altitude.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.189-192
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• 2011

In solid rockets, a pintle thruster is a modulatable thrust device which controlls nozzle throat area. In this study, effect of bore on aerodynamic loads in a SNECMA modulatable thruster was carried out. Existence of bore resulted in reduced aerodynamic load.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.392-398
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• 2009

Theoretical thrust equations for the diverse nozzle expansion condition were derived. By using the obtained thrust equations, parametric studies were carried out to estimate the effect of pressure exponent, minimum operation pressure, ambient pressure and extinguishment pressure on thrust modulation performance in pintle-nozzle solid rocket motors. Analysis results showed that thrust turndown ratio can be easily attained by small nozzle-throat area variation at high pressure exponent, low minimum operation pressure, high ambient pressure and high extinguishment pressure condition. At those conditions, the highest chamber pressure to obtain the intended thrust turndown ratio can be minimized.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.225-229
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• 2012

대기가 희박한 고고도 환령이나 급격한 선회를 위해 2차분사에 의한 추력벡터제어를 사용한다. 8개의 2차분사구를 갖는 고체로켓모터를 대상으로, 2차분사의 유량을 조절하는 밸브의 개도가 추력, 측추력 및 롤 모멘트에 미치는 영향을 해석적으로 연구하였다. 정상 상태의 3차원 Reynolds Averaged Navier-Stokes 식의 해를 구하였으며, 난류를 위해 Spalart-Almaras 모델을 사용하였다. 수치해석의 타당성을 평가하기 위해 실험 결과와 해석결과를 비교하였다. 밸브의 개도가 증가함에 따라 추력은 감소하나 측추력은 증가한다. 반면, 롤 모멘트의 경우, 밸브와 2차분사 파이프의 상호작용에 의해 개도에 비례하지 않는다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.14-15
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• 2002

기체역학 이론에 의하면, 노즐의 공급압력과 노즐의 상세형상이 주어지는 경우에 추진 노즐로부터 방출되는 제트유동의 추력을 예측할 수 있으며, 최대추력은 노즐 출구에서 유동이 적정팽창 상태로 될 때 얻어진다. 실제의 추진 로켓에서나 다른 비상체에서는 추력의 예측뿐만 아니라, 얻어지는 추력의 방향을 적절하게 조절하여 제어하는 것이 요구된다. 종래 추력벡터 제어를 위해서 많은 연구들이 수행되었다. 일례로 추진노즐 내부에 베인(vane) 등을 삽입하여, 추력벡터를 조절하거나, 추진 노즐을 가변(movable nozzle)으로 하는 방법, 그리고 노즐내부에 2차 유동을 분사(secondary flow injection)하여 평균 추력벡터를 제어하는 방법 등이 제안되어 응용되어 왔다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.392-394
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• 2017

In this study, the surface heat transfer coefficient of the 3D model of a thruster regulator in the high temperature and high pressure environment was estimated using the CFD. The thermal barrier coating (TBC) on the surface of the thruster regulator was modeled and the effect of the thickness of the TBC on the temperature of the thruster regulator was investigated. The thickness of the TBC was varied from $100{\mu}m$ to $500{\mu}m$. Results showed that the temperature of the surface and the inside the thruster regulator was lower for the thicker TBS case.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.43-53
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• 2022

In this study, analysis of the flow characteristics of pintle-controlled nozzle with split-line TVC system and the thrust performance prediction was performed. The numerical computation was verified by comparing the thrust coefficient derived from the analysis results with the experimental data. By applying the same numerical analysis technique, the flow characteristics of nozzle were confirmed according to operating altitude, pintle stroke position and TVC angle with the 1/10 scale. As the TVC angle increased, thrust loss occurred and the tendency of AF was different depending on the position of the pintle stroke. Based on the analysis results, the relation of thrust coefficient was derived by applying the response surface methods. The thrust performance model with a slight difference of 1.2% on average from the analysis result was generated.

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.15-21
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• 2017

In this study, the surface heat transfer coefficient of the 3D model of a thruster regulator in the high temperature and high pressure environment was estimated using the commercial CFD code. The thermal barrier coating (TBC) on the surface of the thruster regulator was modeled and the effect of the thickness of the TBC on the temperature of the thruster regulator was investigated. The thickness of the TBC was varied from $100{\mu}m$ to $500{\mu}m$. Results showed that the temperature of the surface and the inside the thruster regulator was lower for the thicker TBC case.