• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.318-321
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• 2005

The design and performance test of a low NOx gas turbine combustor to be used in 55kW class micro-gasturbine engine was performed in KARI's combustion test facility. The combustor is reverse flow-can type for easy installation of injector and other parts and LNG is used as fuel. The performance targets are $99.5\%$ combustion efficiency, less 10ppm NOx, $30\%$ patten factor and $4\%$ pressure loss. Most of the performances required are satisfied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4093-4099
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• 2014

In this study, the thermal-structural behavior of the combustor assembly of 200 kW micro gas turbine system was performed. The typical combustor assembly consists of a Liner, Inner & Outer Case, Burner and Nozzle ring, etc. There are some gaps and friction elements between the components to compensate for the different thermal expansions of various components. Therefore, the developed finite element model includes nonlinear elements. The boundary support conditions of the combustor assembly significantly affect the stress distribution due to the high temperature gradient. This paper deals with parametric studies to quantitatively determine the effects of the variation of the support conditions on the stress distribution and deformation of various components of combustor assembly. These results may be useful for the design of the combustor assembly.

• The KSFM Journal of Fluid Machinery
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• v.18 no.4
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• pp.22-29
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• 2015

In this study, an in-house program to predict steady state operation of micro gas turbines is constructed using MATLAB. The program consists of two parts: design and off-design simulations. The program is fully modular in its structure, and performance of each component (compressor, combustor, turbine, recuperative heat exchanger and pipe elements) is calculated in a separate calculation module using mass and energy balances as well as models for off-design characteristics. The off-design modules of compressor and turbine use performance maps, which are program inputs. The off-design operation of a micro gas turbine under development was predicted by the program. The prediction results were compared with those by commercial software, and the validity of the in-house program was confirmed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.153-159
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• 2015

In this study, a 2-W micro-gas turbine engine was designed using micro-electro-mechanical systems (MEMS) technology, and analytical and experimental investigations of its potential under actual combustion conditions were performed. An ultra-micro-gas turbine contains a turbo-charger, combustor, and generator. A compressor, turbine blade, and generator coil were manufactured using MEMS technology. The shaft was supported by a precision computer numerical control machined air bearing, and a permanent magnet was attached to the end of the shaft for generation. An analysis found that the cooling effect of the air bearing and compressor was sufficient to cover the combustor heat, which was verified in an actual experiment.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.7-8
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• 2012

The effects of interaction between partially premixed and premixed swirl flames on CO and NOx emissions were experimentally investigated using a hybrid/dual swirl jet combustor for a micro-gas turbine. Under the condition of constant angle ($45^{\circ}$) for outer swirl vane, the angle and direction of inner swirl vane installed for a partially premixed flame were varied as main parameters with a constant fuel flow rate for each nozzle. It was found that for all conditions, CO and NOx emissions were measured below 4 ppm and 15 ppm at 15% $O_2$, respectively, in a wide range of equivalence ratio (0.6~0.9). For co-swirl flows, CO emission increased dramatically as the angle of inner swirl vane increased from $15^{\circ}$ to $45^{\circ}$ near lean-flammability limit (i.e. equivalence ratio of 0.5). On the other hand, the case of swirl $angle=45^{\circ}$ provided the lowest NOx emission at higher equivalence ratios than 0.6. For counter-swirl flows, the case of swirl $angle=45^{\circ}$ extended the lean-flammability limit but higher NOx emissions were found compared to those of co-swirl flows. These results could be inferred by interaction between (inner) partially premixed and (outer) premixed swirl flames. However, these estimations were not clear yet because there was insufficient data on turbulent flow structure and fuel-air mixing in the present experimental approach.

• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.19-24
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• 2014

Development of long-term mobile energy sources for mobile robots or small-sized unmanned vehicles are actively increasing. The micro gas turbine generator (MTG) is a good candidate for this purpose because it has both of high energy density and high power density, and 500W class MTG is under development. The designed MTG can be divided into 2 main parts. One part consists of motor/ generator and compressor, and the other one consists of combustor, recuperator and turbine. 500W class MTG is designed to operate at ultra-high speed of 400,000 rpm in high turbine temperature over $700^{\circ}C$ to improve the efficiency. Because the magnetism of NdFeB permanent magnet for the motor/generator could be degraded if the temperature is over $150-200^{\circ}C$, MTG needs the thermal insulation to block the heat transfer from combustor/turbine side to motor/generator side. Moreover, the motor/generator is allocated to get the cooling effect from the rapid air flow by the compressor. This study presents the experimental results to verify whether the thermal insulator and air flow are effective enough to keep the motor/generator part in the low temperature less than $100^{\circ}C$. From the motoring test by using the high temperature test rig, it was confirmed that the motor/generator part could maintain the temperature less than $50^{\circ}C$ under the condition of 1.0 bar compressed air.

• 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.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.320-327
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• 2002

In concert with the growing emphasis placed on distributed power generation there will be a need, in the first decade of the 21th century, for a compact thermal energy system capable of providing the total energy needs of individual homes. A natural gas fueled co-generation micro-turbine with ultra low emission will meet this need. Market opportunities for a distributed micro turbine co-generation system are projected to increase dramatically. In this paper, It was determined that with current state of art component performance levels, metrallic materials, thermal efficiency goal of $28\%$ at sea level standard day conditions are attainable. Higher overall thermal efficiency of $78\%$ is attainable with micro-turbine combined with exhaust fired boilers.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.51-57
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• 2012

Performance evaluation of a compressor is conducted to develop 500W class ultra-micro gas turbine (UMGT) for power generation. The performance evaluation is essential to check the performance of the components of UMGT, a radial turbine, a centrifugal compressor, an angular combustor and a shaft, which have been already designed in previous researches. The purpose of this study is to introduce the development process of the performance testing equipments of the UMGT and to present the results of compressor performance test. For the performance evaluation of the compressor, two test equipments are developed and the initial test equipment uses commercial static air bearings with long shaft. In the improved test equipment, static air bearing is improved to increase rotating speed and compressed nitrogen gas is used for utility gas of the static air bearing to supply compressed air in a stable and steady way. To increase rotating speed to 320,000 rpm, 80% speed of design speed, compressed air is provided to the turbine. The performance map of the compressor with the 50%, 60%, 70%, 80% speed of design point is presented. The results of the performance test of compressor show a good agreement with the results of 3D CFD.