• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.2
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• pp.31-37
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• 2004

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.665-670
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• 2004

This paper reviews the latest studies of the expander cycle Air Turbo Ramjet engine (ATREX) conducted in JAXA. First, a system analysis including the vehicle and trajectory was conducted to optimize the engine cycle and turbo-machine configuration. We selected the precooled turbo-jet cycle for a prototype engine using the near term technologies. Second, a system ground-firing test was conducted to verify a defrosting system for the precooler. Methanol injection with its particles atomization could compensate 80 % of pressure loss caused by the frost. Thirdly, a feasibility of carbon/carbon composites for the engine components was investigated by making complex shapes such as a heat exchanger and a plug nozzle. Basic technologies on the gas leakage, the junction and bonding were also studied. The end of the paper, some basic studies such as wind tunnel tests of a new type air inlet and a plug nozzle are described.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.361-366
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• 2001

A mim turbo-shaft engine of 50HP for UAV, which can be easily modified to turbo-prop and turbo-jet engine by sharing the core engine and has many applications to civilian demands and munitions, will be developed This kind of micro gas turbine engine has been developed mostly by the corporations which have special technology but are small in its scale. Especially, the gas turbine engine can be easily applied to other fields and developed by domestic technology, so that the sharing of technology is planed to realize through the cooperations with academies and research institutes. In this paper, the gas turbine engine, which has the compressor ratio of 3.8, the turbine inlet temperature of l180K and the engine speed higher than 100,000 rpm, is composed of centrifugal compressor, combustor, gas generator turbine, free power turbine and gear box. The competitiveness of the gas turbine engine can be obtained from minimizing its cost by the utilization of domestic infrastructure for the performance test and the decisive outsourcing.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.15-23
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• 2008

A numerical method based on the prediction of total pressure loss of major components of the engine has been developed for prediction of the windmilling start performance of micro-turbojet engine. The start performance in on/off design region has been analysed by applying this method to predict windmilling start-able regions of the centrifugal-type engine. The results of this analysis have been validated by comparing with the test data. The effect of each design parameters on windmilling start performance has been analysed for the enlargement of start-able regions.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.1-8
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• 2016

Micro turbojet engine test and infrared signal measurement were conducted to understand the characteristics of the engine performance and infrared signal with the variants of the exhaust nozzle configuration. A cone type nozzle and five rectangle type nozzles which has aspect ratio from one to five were used for the experimental work. The results show that there are not much difference between cone and rectangle nozzles of the thrust and specific fuel consumption. However infrared signal from exhaust gas become smaller as increasing aspect ratio.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.583-586
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• 2017

Infrared signal measurement are conducted from a micro-turbo jet engine with different nozzle configurations. The conventional cone type, a S-shaped type with aspect ratio 5.2 and five rectangular type nozzle with different aspect ratios are used for this experiment work. The result show that infrared signal from the exhaust gas decrease as the aspect ratio increase. In case of S-shaped nozzle, the maximum infrared signal is reduced about 28.4% when compared of rectangular nozzle with aspect ratio 5(AR5).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1869-1878
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• 2001

Experiments are carried out to investigate the effect of pulsations on the flow and heat transfer characteristics of an axisymmetric impinging jet on a flat plate heated by using a gold coated aim. Vertex motion in the impinging jet is visualized using a fog generator, and a thermochromatic liquid crystal (TLC) technique is used to measure the time averaged local temperature distributions on the impingement plate. In addition, the quantitative data for mean velocity and turbulence intensity are obtained employing hot-wire anemometer. Parameters such as pulsating frequency (f = 0, 10 and 20 Hz) and the nozzle-to-palate spacing (H/D = 2, 10) are considered at the jet Reynolds number of 20,000. Consequently, the significant changes of flow structure and local Nusselt number distribution due to pulsations are observed. In the case of H/D = 2, the enhanced heat transfer coefficient exceeding 30 % is observed at the stagnation point. At the high H/D, heat transfer rate increases with pulsation frequency.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.434-443
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• 2014

A turbo fan engine performance analysis and the optimization using particle swarm optimization(PSO) algorithm have been conducted to investigate the effects of major performance design parameters of an aircraft gas turbine engine. The FJ44-2C turbofan engine, which is widely used in the small business jet, CJ2 has been selected as the basic model. The design parameters consists of the bypass ratio, burner exit temperature, HP compressor ratio, fan inlet mass flow, and nozzle cooling air ratio. The sensitivity analysis of the parameters has been evaluated and the optimization of the parameters has been performed to achieve high net thrust or low specific fuel consumption.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.23-23
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• 2000

대표적인 잠수함 발사 유도탄의 수중에서의 발사 개념에 대한 기술 동향을 분석하였다. 세계 각 국의 수중 발사 유도탄 중 발사 형태가 특히 다른 Tomahawk, Sub Hapoon, Exocet SM39 유도탄에 대하여 그 발사 방법에 따른 기술 동향과 장단점을 비교 분석하였다. 대표적인 서방 세계 수중 발사 유도탄인 Tomahawk는 여러 가지 다른 형태가 있지만 잠수함 발사는 Wet Capsule에 의해 보호되며 어뢰 발사관을 이용하여 압축수에 의해 수중으로 배출되는데 잠수함과의 안전거리에서 견일줄이 유도탄 진행에 따라 장력을 발생 부스터를 점화시킨다. 이 부스터에 의해 수면까지 부상하며 부스터에 설치되어 있는 수중궤적 제어용 Jet-Tab이 수중운동을 제어한다. 수면에서 부스터의 추진력에 의해 대기로 진입하는데 일정속도 이상으로 가속된 후 부스터를 분리시키며 Turbo 엔진이 점화되어 계속 비행하게 된다.(중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.354-358
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• 2007

An experimental study was performed to understand spray characteristics of the slinger injector. system for the micro turbojet engine. In this fuel injection system, fuel is sprayed and atomized in the combustor by centrifugal forces of engine shaft. This experimental apparatus consist of a high speed rotating Spindle, slinger injector, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the droplet size(SMD) is largely affected to rotational speed, mass flow rate and the number of injection orifice. From the this experimental study, we could understand the spray characteristics of the slinger injection system and obtain the optimum shape of the slinger injector nozzle which is suitable for the micro turbojet engine.