• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.411-418
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• 2004

Tip clearance of centrifugal compressor affects the performance. Larger tip clearance results in lower efficiency. What really affects the performance is the running tip clearance, not the cold tip clearance. When the compressor is operating, blade strain and the pressure difference between impeller backplate and hub affects the running tip clearance. This paper describes measured running tip clearance and its effects on the performance of centrifugal compressor. Cold tip clearance before operation was 0.4 mm and running tip clearance varied from 0.86 mm to 0.25 mm with impeller exit pressure. As the pressure at impeller exit increases, the routing tip clearance tends to decreases. The target running tip clearance for compressor at $100\%$ speed was 0.3 mm and it turned out to be exactly 0.30 mm from experiment.

• 설비공학논문집
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• 제17권8호
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• pp.754-763
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• 2005

This paper introduces a new concept compressor in which piston orbits in the cylinder having an annular space formed between two concentric circular walls. In this configuration, two gas pockets are formed with $180^{\circ}$ phase difference: one between the wrap of the orbiting piston and the inner cylinder wall and the other between the piston wrap and the outer cylinder wall. This alternating feature of gas compression and discharge processes yields several advantages such as low torque variation and low gas pulsation. Computer simulation program has been developed to evaluate the compressor performance. The volumetric, adiabatic, and mechanical efficiencies of the orbiter compressor are calculated to be $85.6\%,\;97.2\%,\;and\;95.2\%$, respectively, when it is used as an air compressor.

• 한국군사과학기술학회지
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• 제6권2호
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• pp.83-94
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• 2003

Preliminary aerodynamic design of a compressor is carried out to meet the design requirements which are pressure ratio of 13, air mass flow rate of 4 ㎏/s and rotational speed of 45,000 rpm. The compressor type is chosen as an axial-centrifugal compressor from the design requirements which is suitable for a medium power class turboprop or turboshaft engine. Its overall isentropic efficiency is estimated to be 0.796 and its surge margin to be 20% exceeding the design requirement. This paper summarizes the aerodynamic design details including the design procedures and the results of the axial -centrifugal compressor.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2621-2624
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• 2008

The study on the measurement method of the aerodynamic performance of a turbo compressor was conducted. It is well known that the performance and the efficiency of the compressor can be calculated from the temperature and pressure distribution in each stage of the compressor. In the past Pitot tubes and thermocouples were used to measure pressure and temperature respectively, and recently pressure and temperature rake is used in order to decrease the measuring time and the number of measurement. The miniature total pressure rake which is available in the compressor with a small axial gap is designed and is under development.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.113-118
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• 2008

For a R134a rotary vane compressor used for car air conditioners, characteristics of gas compression and oil supply have been studied. The compressor model under investigation has the low volume ratio of suction to discharge volumes so that there occur flow reversal from discharge port to compression chamber as the leading vane passes over the discharge port. As a result, the volumetric and adiabatic efficiencies turn out to be relatively low compared to other types of displacement compressors. Oil supply mechanism has been comprehended for mathematical modeling and oil flow rate has been calculated for the individual oil passages. This study on the gas compression and oil supply of a rotary vane compressor can be applied to a future design practice on a similar type of compressor.

• 한국유체기계학회 논문집
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• 제15권2호
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• pp.12-19
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• 2012

This study presents unsteady and unstable characteristics of three stage transonic axial compressor, developed by Korea Aerospace Research Institute. As approaching to the unstable operating region at the 103% design speed of the compressor, a modal type stall precursor appears in front of highly loaded 3rd rotor row at first, and it propagates to the upstream. On the contrary, actual stall cell initiates from the stall precursor in front of the 1st rotor row, and it propagates to the downstream of the compressor. After the stall region reached the 3rd stage and stall cell rotates circumferentially about 360 deg, it develops to one dimensional compressor surge mode. It shows a mild surge behaviour with 3~4 Hz frequency. From the test data, it can be suggested that there is a priority to give an optimum blade loading distributions to construct a multi stage transonic axial compressor stages either to secure more stable compressor operating ranges, or to maximize the compressor efficiency.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.230-236
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• 2001

We developed a built-in sensor bearing to measure the rotor motion of a rolling piston type compressor for the air conditioner. Because of needs for the high efficiency and long life span of compressor, and the usage of alternative refrigerants, the operating condition of the compressor becomes more severe. The accurate measurement of the rotor motion of the compressor can contribute greatly to the design and analysis of the hydrodynamic bearing. However, it is difficult to measure accurately the shaft behavior of small compressor because of the small space for the sensor mount, high temperature and pressure of compressor, oil mixed with refrigerant, and electromagnetic noise of the motor. To overcome these difficulties, we develop the cylindrical capacitive sensor that is built in the hydrodynamic bearing and calibrate the built-in sensor bearing indirectly through measuring the oil relative permittivity. We measured the rotor motion as well as suction and discharge pressures in various conditions. The several experimental results show that the developed built-in sensor bearing can measure the rotor motion not only in steady state but also in transient state.

• 에너지공학
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• 제5권2호
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• pp.160-169
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• 1996

석탄가스화복합발전소의 가스터빈 공기압축기와 공기분리장치 간의 최적 연계설계를 위한 매개변수 연구를 수행하였다. 본 연구에서는 복수형 증류탑공정의 공기분리장치를 사용하였으며, 증류탑공정의 특성으로부터 압축기와의 연계조건인 공기추출량, 공기추출압력 및 공기/질소 열교환 조건들을 정의, 수식화하였다. 공기분리장치와 연계된 가스터빈용 공기압축기의 성능변화는 유선곡률방법과 압력손실모델을 결합한 해석방법을 사용하였으며, 예측결과들을 실제 압축기성능 시험결과와 비교하여 예측정확도를 검증하였다. 본 압축기성능 해석방법을 이용하여, 압축기와 공기분리장치의 연계조건인 열교환기의 핀치포인트 온도차, 추출공기량 및 추출 공기압력이 압축기성능에 미치는 영향을 정량적으로 검토하였다. 공기추출량이 늘어나거나 핀치포인트 온도차가 커질수록, 압축기의 압축비 및 소요동력은 증가하였다. 반면에, 압축기 효율은 공기추출량의 증가에 따라 고압공기추출시에는 저하되고, 저압공기추출시에는 향상되었다. 더나아가, 압축기의 일반화된 입구조건과 효율간의 특성곡선을 통해, 압축기 효율을 극대화 할 수 있는 압축기/공기분리장치간의 최적연계조건을 제시하였다.

• 항공우주기술
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• 제7권2호
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• pp.46-52
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• 2008

5MW급 발전용 가스터빈의 주요 구성품 중 압축기에서의 성능시험 및 해석을 위해 측정 파라미터와 그 파라미터를 계측하기 위한 센서류를 선정하고자 한다. 축류압축기의 경우 각 단의 케이싱에서 정압 분포를 평균하여 계측하고, 내부 유동장에서 Kiel 온도관을 이용하여 전압 및 전온도 분포를 계측한다. 원심압축기의 경우 임펠러 출구의 허브면과 팁면에서의 정압 분포는 일반적으로 상당한 차이가 존재하므로 각 면에서 정압을 측정하여 평균하고, 디퓨저 내부와 디스월러 내부에서의 정압 분포를 계측하기 위해 한 피치에서 5개의 유선을 따라 10 곳에서 정압을 측정하고자 한다. 또한 압축기 내 유동특성과 동익-정익간의 상호작용을 고찰하기 위해 5공 피토관을 이용하여 내부 상세유동을 계측한다.

• 설비공학논문집
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• 제11권2호
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• pp.193-204
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• 1999

Performance of a variable-speed, roller-type vane compressor was evaluated at low evaporating temperature. First, an experimental investigation was conducted to examine the performance variation as functions of both outdoor temperature and rotating speed. For this purpose, a typical heat pump was implemented as a test apparatus to measure mass flow rate and power input. Secondly, computational investigations corresponding to the heat pump test conditions were performed to predict compressor performance using ORNL Map-Based compressor model. Results obtained from the heat-pump experiments showed that both mass flow rate and power consumption were sensitively dependent on both evaporating temperature and compressor speed as was predicted from the computational results. From the comparisons of both experimental and computational results, it was well recognized that the ORNL model was subjected to larger error in the accuracy of prediction as outdoor temperature decreased. When the outdoor temperature was above $-5^{\cire}C$, errors of predicted values corresponding to both mass flow rate and power consumption were estimated as $\pm$10% and $\pm$ 15%, respectively. Finally, it is suggested that the ORNL model needs to be re-evaluated if compressor map data tested below $-5^{\cire}C$(in evaporating temperature) are available.