• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.99-106
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• 1998

The performance of the turbofan engine, a medium scale civil aircraft which has been developing in Rep. of Korea, was analyzed and the control scheme for optimization the performance was studied. The dynamic and real-time linear simulation was performed in the previous study The result was that the fuel scedule of the step increase overshoot the limit temperature(3105 $^{\cire}R$) of the high pressure turbine and got small surge margine of the high pressure compressor. Therefore a control scheme such as the LQR(Linear Quadratic Regulator) was applied to optimizing the performance in this studies. The linear model was expected for designing controller and the real time linear model was developed to be closed to nonlinear simulation results. The system matrices were derived from sampling operating points in the scheduled range and then the least square method was applied to the interpolation between these sampling points, where each element of matrices was a function of the rotor speed. The control variables were the fuel flow and the low pressure compressor bleed air. The controlled linear model eliminated the inlet temperature overshoot of the high pressure turbine and obtained maximum surge margins within 0.55. The SFC was stabilized in the range of 0.355 to 0.43.

• Tribology and Lubricants
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• v.30 no.1
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• pp.9-14
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• 2014

In this Part II study, rotordynamic stability analyses were carried out to confirm improvements to the stability of a process high-speed lightweight centrifugal compressor, depending on the effects of tilting pad journal bearing designs. The bearing design variables considered were the clearances, LBPs, LOPs, and preloads. The results showed that the rotordynamic stability of the subject compressor rotor-bearing system improves exactly in accordance with the effects of the bearing design variables, which were determined in the preceding Part I study, owing to reduced bearing stiffnesses. Specifically, it was confirmed that the stability of the rotor system can be greatly improved by increasing both the machined and assembled bearing clearances, but there were no stability improvements by simply changing from an LBP to an LOP design. In addition, it was confirmed that for given fixed machined bearing clearances, the stability can be additionally improved by decreasing the preloads, i.e., by increasing the assembled clearances. In conclusion, it may be necessary to improve the designs of the original tilting pad bearings to obtain a sufficient margin of rotordynamic stability against a possible aerodynamic cross-coupled stiffness in a process high-speed centrifugal compressor. Thus, increasing the machined and assembled bearing clearances and decreasing the preload could be effective solutions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.281-284
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• 2006

An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle) which has been developed by KARI (Korea Aerospace Research Institute). The measurement parameters of Smart UAV propulsion system are gas generator rotational speed, power turbine rotational speed, exhaust gas temperature and torque. But two measurement such as compressor exit pressure and compressor turbine exit temperature were added because they were difficult each component diagnostics using the default measurement parameter. The performance parameters for the estimate of component performance degradation degree are flow capacities and efficiencies for compressor, compressor turbine and power turbine. Database for network learning and test was constructed using a gas turbine performance simulation program. From application results for diagnostics of the PW206C turboshaft engine using the learned networks, it was confirmed that the proposed diagnostics could detect well the single fault types such as compressor fouling and compressor turbine erosion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.173-178
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• 1990

로터-베어링축계는 증기및 가스터빈, 터보 발전기, 압축기등 거의 모든 산업 기계류에서 동력 전달의 기본 도구로써 사용되고 있다. 즉 회전에 의한 동력 의전달은 비교적 간단히 대용량의 동력을 효율적으로 전달할 수 있다. 이에 따라 회전기계류에 대한 연구는 산업 혁명 이후 꾸준히 발전되어 온바, 특히 근래에 들어와 산업기계류의 경쟁이 치열하여짐에 따라 산업기계류의 고정 밀화, 고속화, 고신뢰화 요구가 증대하고 있는 현실을 비추어 볼때, 산업 기 계류의 근간을 이루고 있는 로터-베어링 축계의 안정성을 포함한 진동에 관 한 문제는 회전기계류 설계의 주요 기술로써 연구.개발의 필요성이 매우 높 다 하겠다. 회전축계 진동 관련 연구는 두 분야로 대별될 수 있는데 언밸런 스(Unbalance)에 의한 Synchronous진동과 여러가지 원인에 의해 계의 불안 정성을 유발시키는 Nonsynchronous진동으로 나눌 수 있다. 본 연구에서는 이들 연구의 기본이 되는 회전축-베어링계 동특성 해석 프로그램을 개발하 였다. 여러가지 방법이 있으나 여기서는 Holzer가 비틀림 진동에 적용하고, Mykiestad(2)와 Prohl(3)에 의하여 회전축의 횡 진동에 적용된 이후 Lund(4) 등에 의하여 베어링의 영향등이 첨가된 전달 매트릭스 (Transfer Matrix) 방 법을 이용하여 임계속도(Critical Speed), 모우드 형태(Mode shapes)를 예측 하고 불안정 판정(Instability Criteria)등을 할 수 있는 프로그램을 개발하였 다. 특히 Murphy(1)의 다항식 방법(Polynomial Method)에 기본을 두어 기존 의 전달 매트릭스가 가지고 있던 반복, 수렴 시간 문제와 빠뜨리는 임계속도 예측에 대한 개선을 이루었으며 기존 논문과 실험 결과와의 비교 검토를 통 하여 개발된 프로그램의 신뢰성을 검토하였다. 특히, 각종 회전 기계의 소형 화, 경량화 추세에 따라 지반이나 케이싱이 경량이거나 유연하여 회전축과 동적으로 연성된 경우 회전축-베어링-지반으로 이루어진 2중구조의 회전축 계 동특성을 해석할 수 있는 프로그램을 개발하므로서 회전 기계류의 진동 전반에 걸친 문제점에 대한 그 원인과 현상을 명확히 분석하여 국내의 전기 계류의 보다 신뢰성있는 설계 및 제작자료를 확보하는데 기여할 수 있게 하 였다.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.485-491
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• 2001

This paper describes the development of simulation program which is able to design cutter profiles and 3-dimensional geometry for rotors in screw compressor. Based on the symmetric rotor profiles developed previously, cutters are designed and 3-dimensional geometries of rotors are generated used by simulation program. Symmetric rotors are manufactured by a universal milling machine, and surface geometries of them are measured by a 3-dimension scanner. It is shown that simulation program developed is useful to design cutter for rotor manufacturing and to generate the 3-dimensional helicoid geometry of rotor in screw compressor.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.668-671
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• 2001

For the saving of energy consumption, it is necessary that the high efficient energy transfer machine. We found the optimum operating condition of screw water chiller during this performance test. The specifications of compressor for this performance test are as follows. Built-in volume ratio; Vi=2.4, using refrigerant; HCFC-22, nominal motor output; 60kW(80Hp). We found the test results on water cooled chiller standard test condition that the evaporating capacity is increased 8% maximum and 5.6% under same operating condition. and COP is increased 11 % max. and 8% under same operating condition with change of the evaporating inlet/outlet condition. For the results of these test, we can estimate the optimum operating condition of water cooled type screw chiller.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.191-198
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• 2002

Oil-free turbo-compressor supported by compliant foil bearings which remove oil-contamination by elimination of the conventional ball bearing and oil lubrication systems is presented. Turbo-compressor makes two individual air compression with two impellers at operating speed, 39,000rpm. In this study, the rotordynamic effects caused by aerodynamic instability were investigated with variable mass flow rate. Correlation between frequencies of pressure fluctuation in two diffusers and those of excitation forces on rotor were clearly developed in aerodynamic unsteady region. Thus, these results show that it is beneficial to design high speed rotating turbomachinery considering coupling effect between aerodynamic instability and rotordynamic force.

• The KSFM Journal of Fluid Machinery
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• v.6 no.2 s.19
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• pp.62-69
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• 2003

An oil-free turbo-compressor supported by compliant foil bearings which remove oil-contamination by elimination of a conventional ball bearing and oil lubrication systems is presented. Turbo-compressor makes two individual air compressions with two impellers at a operating speed of 39,000 rpm. In this study, the rotordynamic effects caused by aerodynamic instability were investigated with variable mass flow rates. Correlations between frequencies of pressure fluctuation in two diffusers and those of excitation forces on rotor were clearly observed in an aerodynamic unsteady region. Thus, these results show that it is beneficial to design high-speed rotating turbomachinery by considering coupling effect between aerodynamic instability and rotordynamic force.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.977-980
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• 2011

In this paper, explain to development of low pressure axial compressor performance test rig in KARI. Performance test rig consist of a entrance section, rotor, stator, shaft, rig housing, bearing housing and exit section. Test rig design structural optimization to rotor dynamics analysis of the simplified rotor-shaft assembly and flow analysis of entrance/exit section.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.343-344
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• 2010