• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.63-70
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• 2013

To analyze flow characteristics of the side jet thruster with 4 shutters and rectangular nozzles, a 3-D simulation has been implemented. Numerical calculations for two rotation angles of the shutter, have been conducted. Internal recirculation in a chamber and asymmetric flow structure in a nozzle were observed. In addition, the more shutter rotated, the more asymmetries of flow increased, and this phenomena resulted in thrust bias. The degrees of thrust bias and thrust performance with the rotation angles of the shutter were predicted and compared with theoretical thrust.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.116-123
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• 2002

This paper describes the development of gimbals engine actuation system for KSR(Korean Sounding Rocket)-III which performs the attitude control of pitch and yaw axes by thrust vector control of liquid propellant gimbals engine. The development requirements of configuration, performance and environment are introduced, and the principles and details of components and system development are discussed. The developed system successfully fulfilled its own performance and environmental evaluation. It will be planned to perform verification of interface and integration compatibility with other related systems, and then mounted on KSR-III as a flight hardware system.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.151-160
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• 2008

In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF (Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.164-170
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• 2007

In this paper, the development results of electromechanical TVC actuation system is described in the aspect of design, analysis, manufacturing and test. The kinds of prime power for TVC actuation system is classified by the variety of propulsion system of launch vehicle. The electric power by battery is the sole candidate for prime power of TVC actuation system at the view point of feasible domestic infra technologies for the present. The characteristic analysis study is performed between electromechanical and electrohydraulic actuation system with respect to power efficiency, performance and weight efficiency. The electromechanical actuation system has superiority of power and weight efficiency according to less opportunity of power conversion process.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.171.2-171.2
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• 2012

위성 개발에서 추력기는 위성의 경사각 및 고도 등의 궤도 제어 용도 이외에 위성 동작 초기 혹은 비상 상황에서 안정적인 전력 공급을 위한 자세 제어용 구동기로 사용되어야 하므로 매우 높은 신뢰성을 필요로 한다. 국내의 실용위성을 위해 개발되어 사용되고 있는 출력기는 1 파운드의 작은 용량으로 위성 운영에 일부 제약을 주게 된다. 본 논문은 위성 운영에 있어 반드시 필요한 궤도 천이 절차와 관련하여 기존에 사용된 절차를 보완하기 위한 방법에 대해 기술한다. 기존에 개발된 위성에서는 궤도 조정을 위한 자세 변화에 추력기를 사용하였다. 그러나 위성의 무게가 커짐에 따라 자세 변환을 위한 시간이 오래 걸려 궤도 조정 효율이 떨어지는 요인이 되고 있다. 뿐만 아니라, 자세 변화 과정에서 벡터 방향의 추력으로 인해 원하지 않는 궤도 변화가 생기므로 정밀 궤도 결정에도 영향을 주게 된다. 최근에 개발된 위성의 경우, 위성의 기동 성능을 높이기 위해 고성능 반작용 휠을 사용하므로 이를 이용하여 궤도 천이 전에 자세 변화를 하도록 하고 있다. 이러한 방법을 적용한 결과, 정밀 궤도 결정에 도움이 될 뿐만 아니라 자세 변화로 인한 연료 소모를 줄이는 효과도 있어 위성의 수명 연장에 도움이 되는 것으로 확인되었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.82-89
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• 2006

This paper describes the development results of electrohydraulic actuation system which performs the attitude and trajectory control of pitch and yaw motion using thrust vector control for high altitude launching vehicle operated in high vacuum environment (altitude higher than 300 km). As compared with electrohydraulic actuation system for low altitude launch vehicle which operated under altitude of stratosphere, the intensified development requirements, newly adopted design and manufacturing technologies, newly developed test equipments and test results are summarized in this paper. The development test and evaluation of actuation system were successfully accomplished. The developed actuation system will be installed on KSLV-I after finishing verification of interface and integration compatibility with related other systems.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.592-597
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• 2003

Thrust vector control using a coflow-counterflow concept is achieved by suction and blowing through a slot adjacent to a primary jet which is shrouded by a suction collar. In the present study, the flow characteristics of thrust vectoring is investigated using a numerical method. The nozzle has a design Mach number of 2.0, and the operation pressure ratio is varied to obtain various flow features of the nozzle flow. Test conditions are in the range of the nozzle pressure ratio from 6.0 to 10.0, and a suction pressure from 90kPa to 35kPa. Two-dimensional, compressible Navier-Stokes computations are conducted with RNG ${\kappa}-{\varepsilon}$ turbulence model. The computational results provide an understanding of the detailed physics of the thrust vectoring process. It is found that an increase in the nozzle pressure ratio leads to increased thrust efficiency but reduces the thrust vector angle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.913-914
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• 2017

Structural analyses of a engine system is required in development stage for increasing structural reliability and reducing weight. Attitude of a launch vehicle during flight is controlled by combustion chamber rotation varying with TVC (thrust vector control) actuator displacements. In this study nonlinear static analysis is performed for a 75 tonf-class liquid rocket engine using before and after the TVC actuation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.136-152
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• 2004

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.129-136
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• 2004