• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.285-288
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• 2007

Numerical study of the influence of the boundary layer of micro-supersonic jet impinging on a flat plate with a hole was performed, to investigate the role of gas jet to eject melted materials from the cut zone in the laser machining. The detailed shock structures and the information of the mass flow rate through the hole were compared to the results of the previous study, in which the effects of boundary layer inside nozzle was not accounted. It was found that the boundary layer inside the micro- nozzle introduced stronger Mach disc over the machining zone, and thus that the mass flow rate through the hole decreased.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.6
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• pp.30-37
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• 2008

Many theoretical and experimental studies have been conducted to investigate elements of swirl injector hydrodynamics, such as variations in liquid film thickness or air core diameter. From these studies, some theoretical relationships have been established through an approximate analytical solution of flow hydrodynamics in a swirl nozzle. However, experimental studies on elements such as the stability of internal flow have not produced conclusive results. In this study, the stability of the internal flow under tangential entry conditions was examined by visualizing the formation of the air core in the swirl chamber and measuring the liquid film thickness in the orifice.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.93-95
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• 2005

VASIMR (Variable Specific Impulse Magnetoplasma Rocket: JSC, NASA)의 개념을 바탕으로 하는 K2H (KBSI-KAIST-Hanyang University)라고 이름 붙여진 우주 추진체 모사장치 (Space Propulsion Simulator)를 개발하였다. 이 장치는 헬리콘 플라즈마 소스, 이온 가열부 (ICRH: Ion Cyclotron Resonance Heating), 자기노즐 부분으로 이루어져 있다. 헬리콘 플라즈마 소스는 m=+1 형태의 Right-helical 안테나를 사용하여 발생하였다. 본 연구에서는 K2H 장치의 기본적인 설계 개념 및 초기에 발생한 헬리콘 플라즈마의 물성을 RF 보상탐침을 이용하여 측정하였다. 그 결과 900 W, 13.56 MHz rf파워를 사용하여, 아르곤 7 mTorr하에서 전자밀도 = $10^{12}-10^{13}cm-3$, 전자온도 = 4-6 eV의 헬리콘 플라즈마를 안정적으로 발생시켰다.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.23-29
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• 2006

In an annular injection supersonic ejector, the supersonic primary flow is injected along the side wall, therefore a funnel-shaped shock wave is generated by the contraction angle of the mixing chamber. In the present study, we developed a simple funnel shock wave model using 2-D wedge and conical shock wave relations. In result, the secondary flow pressure can be predicted more accurately than using a simple 2-D wedge shock wave model. Through the same analysis, the compression ratio and the adiabatic efficiency according to the entrainment ratio were calculated.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.38-43
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• 2006

In the present study, preliminary design and analysis for a jet pump, which is able to transfer fuel from the tank to the engine, were performed as an aerospace component technology development project. The jet pump is a core part, which is normally installed in the fuel tank, to supply the fuel from the tank to the engine feed pump, or to transfer the feed between tanks. In order to design preliminarily installed in the jet pump, equations for design were modelled using SIMULINK, and the design was carried out based on the simulation model.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.44-53
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• 2006

In this study, the non-destructive computed tomography was adopted to observe the density profile of the needle-punched Carbon/Carbon(C/C) composites nozzle throat. The density profile of C/C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.3
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• pp.30-37
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• 2003

Spray angle of dual swirl injector is established according to the velocity ratio at orifice exit. Due to the internal mixing at recess and lack of correlation for the combined two fluid injection, prediction of spray angle is very difficult. This study deal with experimental work and numerical simulation on spray angle with different recess length. Among the multiphase flow models, the VOF model was selected to simulate the spray angle. Feasibility of numerical analysis are confirmed by comparing the results with the experimental data, and the effect of recess on spray angle are analyzed for single and combined spray case.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.62-72
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• 2012

Divert and attitude control system(DACS) plays an important role for orbit transfer and attitude control, and therefore becomes important subject for recent space vehicle and Precision Guided Missile(PGM) development. To develop DACS system, main research areas include shape combination of pintle and nozzle to maximize thrust change, and reduction of aerodynamic pintle load to minimizle pintle driving force, and development of multi-axis control algorithm. In this paper, introduction, classification, and overseas/domestic research and development program, and prospects of DACS are reviewed and summarized.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.16-22
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• 2012

Performance of a liquid rocket thrust chamber with regenerative cooling scheme has been numerically analyzed using in-house CFD code which can predict combustion/cooling performance and provide nozzle design parameters. This paper investigates trade-offs between combustion and cooling performance with varying amount of fuel directly injected into the chamber wall to form cooling films and mixture ratios for the peripheral injectors. Further efforts to verify/improve the simulation methodology including comparison with the firing test results are planned to make it a reliable tool to optimize the film cooling and other major design parameters.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.726-728
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• 2010

A subscale gas generator was designed and manufactured to investigate the effect of design parameters on discharge coefficients of injectors for a 75 ton-class gas generator and hot-firing tests were successfully performed. The test results showed that discharge coefficients of fuel and liquid oxygen injectors remained nearly constant irrespective of variations of a mixture ratio and a chamber pressure. When the post diameter of the liquid oxygen injector was reduced, the discharge coefficient was increased as the pressure drop of the injector was decreased.