• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.122-125
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• 2003

For Lab-scale Hybrid Rocket's Ignition, It is needs of heat source to vaporize solid fuel. We used Nichrome wire which has a electric resistance for ignition. But Ignition system by using Nichrome wire is not only the disposable system, but also the system which has an affect on the Hybrid rocket's structures(nozzle throat diameter). The new Ignition system composed of Butane+propane gas' supply devices and spark plug. RPL(Rocket Propulsion Lab.) perform the hybrid rocket experiments over 50 times by using new ignition system. The fact that is possible to throttle the Thrust in hybrid rocket is confirmed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.640-647
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• 2002

An experimental investigation or the sonic and supersonic air ejector systems has beer conducted to develop design and prediction programs for practical ejector system. Five different primary nozzles have been employed to operate the ejector systems in the ranges of low and moderate operating pressure ratios. The ejector operating pressure ratio for the secondary chamber pressure to be minimized has a strong influence of the ejector throat ratio. The pressure inside the ejector diffuser is not dependent on the primary nozzle configurations employed but only a function of the ejector operating pressure ratio. Experimental results show that a supersonic ejector system is more desirable for obtaining high vacuum pressure of the secondary chamber than a sonic ejector system.

• 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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• 2012.05a
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• pp.262-267
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• 2012

For DACS system which controls pintle position to change nozzle throat area, one actuator has been used for each modulatable pintle thruster. This ten actuator system drove to complex system structure and complicated control mechanism. In order to overcome this shortcomings, international patents were reviewed, analysed and presented.

• 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 Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.31-38
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• 2014

Ejector is a simple device which can transport a low-pressure secondary flow by using a high-pressure primary flow. The efficiency of the ejector system is relatively very low, compared to other fluid transport devices driven mainly by the forces acting on the normal direction. However, its major advantage is a simple structure with no moving parts, and it transports a large amount of fluid with a small driving energy. In this study, the performance of side-type liquid ejector commonly used in ships; is analyzed by using experimental and CFD methods under steady and incompressible flow condition by varying the length of the throat and diffuser, the flow pattern and suction phenomenon were studied in detail.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.107-113
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• 2005

A calorimeter of 2-ton thrust level rocket engine chamber has been developed to measure the wall heat flux. The liner of the chamber is made of copper-chromium alloy to maximize the heat transfer performance and structural strength. 1-D design code based on empirical correlations has been used for the prediction of the global thermal characteristics while 3-D CFD has been applied for the verification of local cooling performance. The predicted average wall heat flux at the throat is 43 $MW/m^{2}$ for the combustion chamber pressure of 53 bar. The chamber structure is confirmed to be safe at the pressure of 150 bar through 2-D stress analysis and measurement of the strain of the test species. Finally, the test of pressurizing the calorimeter chamber has been performed with water at the pressure of 150 bar in room temperature environment. No thermal damage has been detected after the hot-fire test in the test nozzle of same cooling performance with the developed calorimeter though the measured throat heat flux is higher than the design value by 10%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.64-70
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• 2005

The overall results of hot firing tests of fuel-rich gas generator with impinging injector at design and off-design points are described. The gas generator consists of an injector head with impinging injector, a water cooled combustor wall, a turbulence ring to enhance mixing, an instrument ring measuring temperature and pressure and a nozzle. The combustion tests were successfully performed without damage of gas generator. Test results show that the outlet temperature is not dependent on residence time of hot gas within 4～6msec but dependent on chamber pressure. The relation between outlet temperature and combustion efficiency resulting from measured pressure, mass flow rate and area of nozzle throat is shown. The overall O/F ratio is the critical parameter to determine the outlet temperature and the linear correlation between two parameters is established.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.156-160
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• 2007

Ejector system is a device to transport a low-pressure secondary flow by using a high-pressure primary flow. Ejector system is, in general, composed of a primary nozzle, a mixing section, a casing part for suction of secondary flow and a diffuser. It can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejector system is simple in construction and has no moving parts, so it can not only compress and transport a massive capacity of fluid without trouble, but also has little need for maintenance. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an applicable model and operating conditions for an ejector in the condition of sonic and subsonic, which can be extended to the hydrogen fuel cell vehicle. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Optimization technique and numerical simulation was adopted for an optimal geometry design and satisfying the required performance at design point of ejector for hydrogen recirculation. Also, some sonic and subsonic ejectors with the function of changing nozzle position were manufactured precisely and tested for the comparison with the calculation results.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.1
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• pp.31-37
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• 2009

An ejector is a machine utilized for mixing fluid, maintaining a vacuum, and transporting fluid. The Ejector enhances system efficiency, are easily operated, have a mechnically simple structure, and do not require a power supply. Because of these advantages, the ejector has been applied to a variety of industrial fields such as refrigerators, power plants and oil plants. In this work, an ejector was used to safely recycle anode tail gas in a 5 kW Molten Carbonate Fuel Cell system at KEPRI(Korea Electric Power Research Institute). In this system, the ejector is placed at mixing point between the anode tail gas and the cathode tail gas or the fresh air. Commercial ejectors are not designed for the actual operating conditions for our fuel cell system. A new ejector was therefore designed for use beyond conventional operating limits. In this study, the entrainment ratio is measured according to the diametrical ratio of nozzle to throat in the designed ejector. This helps to define important criteria of ejectors for MCFC recycling.