• Proceedings of the KSME Conference
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• 2001.11b
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• pp.788-793
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• 2001

Test experience with a micro-turbine jet engine is introduced. The engine provides us with valuable opportunities to experience know-hows essential for engine development. It consists of a single radial compressor and a single stage turbine. Engine starting procedure has been established after many trials and errors. Static and dynamic engine performance tests were conducted. Static performance was found to be inferior to that advertised by the manufacturer. Further improvement is needed. Dynamic performance revealed that engine thrust overshoots unfavorably for the purpose of UAV control.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.389-394
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• 2014

In this paper, we report a new manufacturing method for friction reduction using micro-AAJ (abrasive air-jet) machining. AAJ machining employs compressed air to accelerate a jet of high-speed particles to mechanically machine features, including micro-channels and micro-holes, into glass, metal, or polymer substrates for use in microfluidics, MEMS (micro electromechanical systems). And we introduce the micro-AAJ machining system, which consists of a micro-AAJ nozzle and a five-axis positioning system. Various micro-AAJ nozzles can be used, depending on the required surface structure, and three-dimensional machining is possible. We machined samples under six different conditions and describe machining results obtained while using it. We also measured the coefficient of friction of micro-textured surfaces. We report the coefficient of friction of micro-textured surfaces patterned using micro-AAJ machining for engine piston ring.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.319-322
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• 2007

A numerical method for prediction of the Windmilling start performance of micro-turbojet engine has been developed. The method incorporates the available loss correlations and analyses for the estimation of the performance of the major engine components. It has been applied to the micro turbojet engine with the mixed type compressor. The starting performance characteristics on the on/off-design regions have been analysed. Additionally, the sensitivity of each design parameter which has an effect on Windmilling start performance has been analysed.

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.130-136
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• 2019

Spray visualization of a vaporizer fuel injection system of a micro turbo jet engine was experimentally studied. The fuel heating by combustion was simulated by the high pressure steam generator and combustor inlet air from the centrifugal compressor was simulated by compressed air stored in the high pressure air tank. Spray visualization was performed with single vaporizer, and then six vaporizers which are same number of micro turbojet engine were used. As a results, the spray characteristics of the vaporizer were understood with pressure difference of the combustor inlet air and the fuel supply pressure. Spray angles with three types of vaporizer configuration were measured. In the results, guide vane configuration has a wider spray angle than the straight tube and smooth curve tube with a swirler, so it is expected that the fuel will be effectively distributed inside the combustor flame tube.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.28-39
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• 2022

An experimental study was carried out to understand the characteristics of the long wave infrared signal emitted from the exhaust plume when water is sprayed around it. The micro-jet engine was used to generate the exhaust plume, and eight water spray nozzles were installed around the exhaust nozzle. Two water injection angles were applied, one is sparying parallel to the exhaust plume, and the other is spraying water into the exhaust plume. The measurement results are as follows. When spraying water parallel to the exhaust plume, the long wave infrared signal is decreased with water spray flow rate. When spraying water the exhaust plume, the long wave infrared signal shows a larger value than plume only.

• 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.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.42-49
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• 2014

Test device using virtual engine simulator can help reduce the number of engine tests through tests similar to the actual engine tests and repeat the test under the same condition, and thus reduce the engine maintenance and operating costs. Also, as it is possible to easily implement extreme conditions in which it is hard to conduct actual tests, it can prevent engine damages that may happen during the actual engine test under such conditions. In this study, an upgraded small jet engine performance test device was developed that can conduct both real and virtual engine test by applying real-time engine model to the existing micro jet engine performance test device that was previously developed by authors. This newly developed multi-purpose small jet engine performance test device is expected to be used for various educational and research purposes.

• 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).

• 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.