• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.347-352
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• 2001

In this paper, the pumping performance of the two-stage disk-type drag pump which works in the outlet pressure range from 3 to 0.001 Torr is studied experimentally. The rotational speed of the pump is 24,000rpm, and nitrogen is used as a test gas. The pumping characteristics of various drag pumps are performed. The inlet pressures are measured for various outlet pressures of the test pump. The maximum compression ratios for zero throughput are 1000(two-stage BSC type), 740(helical-type), 90(BSC type) and 85(OSC type), respectively. The ultimate pressure of the two-stage disk-type drag pump is $8.1\times10^6$ Torr.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2535-2542
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• 2000

The regulator system has been modeled and combined to a swashplate type axial piston pump. Linear approximation has been performed for nonlinear coefficient terms of an axial piston pump-regulator model without significantly affecting accuracy. Based on the mathematical model of an axial piston pump-regulator system, a couple of characteristic curves of negative flow control and horsepower control are drawn, which show a good correlation with those of experimental results. So the simplified axial piston pump-regulator model in this paper is expected to be utilized not only for the design and analysis of hydraulic circuit of excavator but also for prevention of engine overload.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.538-541
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• 2007

An expansion device plays an important role in optimizing the heat pumps by controlling refrigerant flow and balancing the system pressures. Conventional expansion devices are being gradually replaced with electronic expansion valves due to increasing focus on comfort, energy conservation, and application of a variable speed compressor. In addition, the amount of refrigerant charge in a heat pump is another primary parameter influencing system performance. In this study, the flow characteristics of the expansion devices are analyzed, and the effects of refrigerant charge amount on the performance of the heat pump are investigated at various operating conditions. Cooling capacity of the heat pump system is strongly dependent on load conditions. The heat pump system is very sensitive with a variation of refrigerant charge amount. But, the performance of it can be optimized by adjusting the flow rate through expansion device to maintain a constant superheat at all test conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.568-573
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• 2000

In this study, experimental and numerical analyses are carried out to investigate the performance of centrifugal pump with various air admitting conditions. Experiments on pump performance under air-water two-phase flow n accomplished using a centrifugal pump with semi-open type impeller having three, five and seven blades, respectively. Also, the numerical analysis of turbulent air-water two-phase flow using finite volume method has been carried out to obtain the pressure, velocities and void fraction on the basis of a so-called bubbly flow model with the constant size and shape of cavity. The results obtained through this study show the reasonable agreements within the range of bubbly flow regime. There are promising developments concerning application of the present study for the flow in a centrifugal pump with two-phase flow conditions and efforts must be followed to improve the turbulence model and two-phase flow model for turbomachinery.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.593-597
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• 2005

In order to study the characteristics of the subsurface vortex the flow fields of the three pump sump models were analysed by the numerical simulation. The calculation results show that there are circulation flows in the pump sump model and maximum vorticity strength which make iso-surface from the wall to the pump inlet could be used for predicting the subsurface vortex generation. Also, the flow field for the sump model with anti-vortex devices simulated and the results shows that there is no vorticity value which make iso-surface from the sump wall to the pump inlet.

• 동력기계공학회지
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• 제3권1호
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• pp.23-28
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• 1999

Experimental and theoretical researches about jet pump have been carried out by many researchers. Jet pump can be used for the transportation of solid materials, farm produce, and fishes. It is the purpose of this paper to seek optimal multi nozzle shape of the annular jet pump. Experiments were done for several jet nozzle areas, jet nozzle arrays and jet nozzle lengths. Water was used for both the primary fluid and secondary fluid. The efficiency curves for the annular jet pump having multi nozzles are presented in this paper.

• 설비공학논문집
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• 제13권6호
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• pp.431-439
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• 2001

Recently, multi-room type heat pump system has aroused much attention, because it can achieve much reduction of installation cost and space as well as energy saving in companion with the single room type heat pump system. In the present study, performance characteristics of a 3 room type inverter driven heat pump system, which is widely spread in Japanese market, are measured.. In the single room operation, performances of a heat pump system such s the difference of compressor outlet and inlet pressures and the mass flowrate may increase with the increase of cooling capacity so that COP of the system decrease with the increase of cooling capacity. However, in the 2 room operation, mass flowrate and COP of the total system increase markedly as compared with the single room operation.

• 한국유체기계학회 논문집
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• 제16권4호
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• pp.28-34
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• 2013

Centrifugal pump consists of a axis, a impeller and a spiral casing. The impeller is the most important component in centrifugal pump. But to minimize flow loss in discharge passage including spiral casing, the shape of spiral casing is very important also. So, to investigate the effect of shape of the spiral casing on performance curve of pump, the characteristics of spiral casing were studied through numerical analysis for centrifugal pump used on industry field. From the results the rectangular model was showed more loss than the others because of asymmetric flow field.

• 한국해양공학회지
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• 제27권6호
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• pp.106-111
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• 2013

In this study, numerical simulations and performance evaluation has been carried out to investigate performance characteristics of air-type high pressure piston pump. ANSYS and CFX were applied for analyzing the structure and flow behavior of air-type high pressure piston pump, respectively. The performance evaluation of high pressure piston pump was performed experimentally, the results were compared with simulation. It was found that the freezing phenomenon was improved by 20% and the pressure fluctuation decreased by 50%, compared with the previous pump.

• 대한기계학회논문집B
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• 제41권10호
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• pp.631-638
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• 2017

원심펌프와 구조 및 작동 원리가 다른 토네이도 원리를 적용한 슬러리 펌프의 성능특성에 미치는 로터 설계형상의 영향에 대한 실험적 연구를 수행하였다. 십자 구조인 로터의 설계변수는 직경, 높이 및 두께로 설정하였으며, 설계변수에 따라 성능특성을 비교하였다. 로터의 직경과 높이가 커지면 펌프효율이 증가하는 반면에, 로터의 두께가 증가하면 효율은 감소하였다. 본 연구의 설계조건에서 높이가 최대인 로터가 직경이 최대인 경우에 비해 비면적은 약간 작지만 펌프효율은 더 높게 나타났다.