• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.183-190
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• 1998

This paper introduces the part of efforts to develop a derivative type turbo-shaft engine from an existing baseline engine for multi-purpose helicopters targeting at 4000kg of take-off weight for 10-12 passengers. As a first step in meeting the development goal of increasing the output power to 840hp from 720hp with minimum modification, two stage axial compressor was redesigned to obtain the higher pressure ratio by removing the inlet guide vane and increasing the chord length. As a result, two stage axial compressors were designed to have the flow rate of 3.04 kg/s, the pressure ratio of 2.01 and the adiabatic efficiency of $85\%$. Its performance tests were carried out and verification of test results and redesign are under progress. Aerodynamic and structural analyses of the preliminary design are mainly described in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.50-57
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• 1997

A 600HP class high-speed gear driven 3-stage turbo-compressor (IGCC : Integrally Geared Centrifugal Compressor) driven by a 3600 rpm AC induction motor has been designed, of which low speed pinion runs at 35000 rpm and high speed pinion at 50000 rpm nominally. Due to its high speed operation, the system requires very reliable bearing selection and design as well as accurate rotordynamic analysis and prediction of its dynamic behavior to secure the operating reliability. Rotordaynamic analyses of the IGCC rotor-bearing system predicted that the low speed pinion rotor mounted on 5-pad tilting pad bearings has two critical speeds before its design speed and high speed pinion rotor only one critical speed, and estimated critical speeds of both pinion shafts are away from the continuous operating speed enough to satisfy the corresponding API requirement. The forced response analysis with API specified maximum allowable unbalances also showed that unbalance responses are small enough for smooth operation of the system.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.109-115
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• 2004

The micro turbo generator is new portable power source based on the Brayton cycle, which consists of a compressor, a turbine, a generator, and a combustion chamber. In this paper, the thermodynamic analysis was performed to find the required condition for hundreds watts power in the micro turbo generator, and also the rotordynamic stability was predicted using the numerical analysis of air foil bearings which support the micro turbo generator. By experimental works, the rotordynamic stability of the micro turbo generator with foil bearings was verified. While various transient dynamic situation, the micro turbo generator had stable performances. From the result, it was demonstrated that air foil bearings could be adapted to the micro turbo generator as a excellent lubrication element.

• 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.

• The KSFM Journal of Fluid Machinery
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• v.3 no.4 s.9
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• pp.38-43
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• 2000

Recently, KARI(Korea Aerospace Research Institute, Korea) and CIAM(Central Institute of Aviation Motors, Russia) have made an effort in developing a centrifugal compressor for a small gas turbine engine as part of a collaboration program. This compressor has been designed as a sub-component for an axial-centrifugal compression system for a small turbo-shaft engine aiming adiabatic efficiency higher than 0.81. The geometrical design requirement imposes restrictions to have high inlet hub-to-tip ratio and inlet swirl flow. In this study, the compressor has been designed using the generalized experimental data established from those compressors having pressure ratio of 3.7 to 5. From this generalized empirical correlation, desirable values of design parameters could be obtained. Subsequently, quasi-3D and 3D viscous flow analyses have been performed to ensure the adopted methodology. It is expected that the centrifugal compressor provides total pressure ratio of 4.89, corrected mass flow-rate of 1.64kg/sec, and adiabatic efficiency of 0.815 with inlet hub-to-tip ratio of 0.641. These relatively high total pressure ratio and inlet hub-to-tip ratio are the main distinctive features in this design. Besides, one of the main features of this centrifugal compressor is the adoption of a double-row bladed diffuser to effectively decelerate the transonic flow leaving the impeller. The compressor has been manufactured and will be tested in the near future.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1187-1193
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• 2011

In this paper, proposed controller preventing compressor surge and reducing the acceleration time of the fuel flow control system for turbo-jet engine. Turbo-jet engine controller is designed by applying fuzzy PID control algorithm and high-gain observer. Observer is used to estimate to compressor rotation speed of turbo-jet engine. Result of fuzzy inference is used as the fuel flow control inputs for preventing compressor surge and flame-out in turbo-jet engine. The controller is designed to converge to the desired speed quickly and safely. Using MATLAB to perform computer simulations verified the performance of the proposed controller.

• Journal of KSNVE
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• v.9 no.5
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• pp.1042-1049
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• 1999

In the Part I has been reported a rotordynamic analysis of the driving motor-bull gear rotor-bearing system of a turbo-chiller. In this study, Part II, a rotordynamic analysis is performed with the turbo-chiller compressor pinion-impeller rotor system supported on two fluid film bearings. The pinion-impeller rotor system is driven to a rated speed of 14,600 rpm through a speed-increasing pinion-bull gear. It is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support bearings, the generalized forces of the gear action as well as the rotor itself. The two support bearings, partial and 3-axial groove bearings, are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the compressor pinion-impeller rotor-bearing system is carried out to evaluate its stability, whirl natural frequencies and mode shapes, and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regardless of operating conditions, i.e., loads and operating speeds.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1395-1400
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• 2004

A centrifugal compressor for geothermal heat pump system using R134a as working fluid has been developed. The centrifugal compressor consists of an impeller with splitters, two vaneless diffuser, a low solidity vaned diffuser and a volute. In this compressor, diffuser blade angles are controlled to satisfy both heating and cooling conditions. A aerodynamic design was done by applying the repeating design procedure including a meanline design, a 3D geometry generation and fluid dynamic calculation. In this paper, design and performance prediction results of the compressor are presented.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.240-243
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• 2008

In this paper, the design of Centrifugal Compressor which is used in sizes 50 horse power has 8 pressure ratio and numerical analysis of the flow within compressor varying tip clearance length are performed. To get high pressure ratio with low power the exit height of impellers is low but compressor has very high speed of revolution. So compressor has high specific speed although mass flow rate is very small. The shape of impellers at the first stage is carried out. Flow and performance characteristics of impellers has been analyzed by using a commercial CFD program, $Fine^{TM}$/turbo. The result shows that loss coefficient is affected by tip clearance length and compressor has proper tip clearance length. It is possible to decrease loss by selecting apt tip clearance length.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.41-46
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• 2015

Recently, the development of the HTS power cable is actively promoted. As the length of HTS power cable increases, there have been many efforts to develop large capacity cryocooler. Among the various cryocooler, the Brayton refrigerator is the most competitive for HTS power cable. The Brayton refrigerator is composed of recuperative heat exchangers, a compressor, and a cryogenic turbo expander. In these components, the cryogenic turbo expander is a part to decrease the temperature and it is the most significant component that is closely related with overall system efficiency. It rotates with high speed using a high-pressure helium or neon gas at cryogenic temperature. This paper describes the design of a 10 kW class Brayton refrigeration cycle and the cryogenic turbo expander. Flow and structural analysis are performed for the rotating impeller and nozzle to verify the efficiency and the design performance.