• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.711-714
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• 2008

The objective of this paper is to know the characteristics of pressure through a simplified typical carburetor used in small engines at the different throttle opening conditions. The carburetor is the device responsible for creating the right air-fuel mixture according to the different engine operating conditions. It is activated by the static or the dynamic pressure. The carburetor dummy is geometrically similar of LPG brush-cutter engine's diaphragm carburetor and is made of acrylic. Suction system gives body to crankcase vacuum using the vacuum pump and throttle opening conditions are controled by transfer device. Carburetor venturi throat and fuel charging tube diameter is each 20mm, 4.1mm. The result of the work presents an unprecedented phenomenon of suction pressure variation inside the carburetor venturi. It is predicted that these unprecedented pressure variation be caused by minor losses; sudden contraction or expansion, open or partially closed and so on.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.776-781
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• 2005

Cavitation is the most serious problem caused in developing high-speed turbopump, and use of an inducer is often made to avoid cavitation in main impeller. Thus, the inducer always operates under the worst condition of cavitation. If it could be possible to control and suppress cavitation in the inducer by some new device, it would also be possible to suppress cavitation occurring in all types of pumps. The purpose of our present study is to develop a new effective method of controlling and suppressing cavitation in an inducer using shallow grooves, named as "J-Groove", J-Groove is installed on the casing wall near the blade tip to use the pressure difference between high pressure region and low pressure region in the axial direction at the inlet of the inducer. The results show that proper combination of backward-swept inducer with J-Groove improves suction performance of turbopump remarkably in the range of partial flow rate as well as designed flow rate. The rotating backflow cavitation occurring in the range of low flow rate and the cavitation surge occurring in the vicinity of the best efficiency point can be almost fully suppressed by installing J-Groove.

• The KSFM Journal of Fluid Machinery
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• v.8 no.2 s.29
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• pp.31-38
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• 2005

A low NPSH and high pressure fuel pump has been designed for a turbopump system. The fuel pump has an axial inducer and a centrifugal impeller. A meanline method has been established for the preliminary design and performance prediction of pumps at design or off-design points. KeRC(Kelyish Research Center) carried out a model testing of the fuel pump with water as a working fluid at the reduced speed. Predicted performances by the method are shown to be in good agreement with experimental results for cavitating and non-cavitating conditions. The established meanline method can be used for the performance prediction and preliminary design of high speed pumps which have a inducer, impeller and volute. In the current study, the three dimensional viscous flow in the fuel pump was investigated through numerical computation. A modified design of the fuel pump was generated to improve pump performance by utilizing CFD results. The modified fuel pump was experimentally tested by ROTEM and KARI(Korea Aerospace Research Institute). The measured non-cavitating and cavitating performance showed a good agreement with designed performance.

• The KSFM Journal of Fluid Machinery
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• v.11 no.1
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• pp.18-25
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• 2008

Recent trends of a centrifugal pump are high speed in rotation and high pressure in head with high efficiency to meet the demands of industries. However, the newly developed pumps make trouble of pressure pulsation in the pumping system by performance instability of the pump. Moreover, cavitation, which is a main obstacle of high rotational speed in the pump, occurring in an impeller gives serious damages to the impeller and casing wall. The purpose of present study is not only to develop a simple method to improve pump performance but also to suppress the occurrence of cavitation in the centrifugal pump by use of J-Groove. J-Groove is a shallow groove installed on the casing wall in the meridional direction. The application of J-Groove to a centrifugal pump with a new type impeller of "semi-closed impeller" has proved its effectiveness as a useful countermeasure of the unstable pump performance and cavitation. The results show that the combination of semi-closed impeller and J-Groove can be applied successfully and improves both the pump performance and suction performance.

• The KSFM Journal of Fluid Machinery
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• v.5 no.2 s.15
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• pp.73-80
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• 2002

운영 자료의 조사$\cdot$분석을 위해 수도권 광역상수도의 취수장, 가압장 및 정수장들을 발문하여 각 펌프장에서 관리하고 있는 운전일보, 기기이력카드 등과 한국수자원공사에서 발간하는 월보 및 년보와 각 단계별 실시설계 보고서 및 준공도소를 수집하여 통계 처리한 결과를 요약하여 보면 다음과 같다. 각 단계별 수도권 광역상수도의 취수량 및 송수량은 운영을 시작한 초기부터 1990년까지 증가하다가 점점 수량이 감소하는 추세이다. 팔당 1 취수펌프장은 계획 취수량의 $95.5\%$, 2 취수펌프장은 $89.8\%$를 공급한 후 계속 감소되었고 설계 시 $100\%$의 용수량을 만족시키지 못하고 있다. 이러한 현상은 최근 IMF로 인하여 건설경기 둔화와 용수 수요량이 감소하였을뿐만 아니라 지방자치단체별로 취수펌프장을 독자적으로 건설하여 수요량 감소가 심화되었기 때문인 것으로 판단된다. 각 단계별 광역상수도 중 펌프의 운전토출압력과 운전흡입압력으로 부터 전양정을 계산하여 보면 설계된정격양정보다 낮은 수치인 저양정$\cdot$대유량으로 운전되고 있음을 알 수 있다. 이러한 운전은 캐비테이션을 발생시키고 이로 인하여 임펠러에 침식이나 균열이 발생하여 10년에 한번씩은 임페러를 교체한 것으로 나타났다. 그리고 펌프의 교체 주기는 $15\~20$년인 것으로 조사되었다.

• The KSFM Journal of Fluid Machinery
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• v.12 no.4
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• pp.14-22
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• 2009

The head-capacity curves for pumps developed by the pump manufacturer are based on tests of a single pump operating in a semi-infinite basin with no close walls or floors and with no stray currents. Therefore, flow into the pump intake is with no vortices or swirling. However, pump station designers relying on these curves to define the operating conditions for the pump selected sometimes meet the reductions of capacity and efficiency, as well as the increase of vibration and additional noise, which were caused by air-entered flow in the pump station. From this background, the authors are carrying out a systematic study on the flow characteristics of intakes within a sump of pump station model. Multi-intake sump model with anti-submerged vortex device basin is designed and the characteristics of submerged vortex is investigated in the flow field by numerical simulation. In this study, a commercial CFD code is used to predict the vortex generation in the pump station accurately. The analysed results by CFD show that the vortex structure and effect of anti-submerged vortex device are different at each pump intake channel.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.

• Fire Science and Engineering
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• v.30 no.2
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• pp.106-113
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• 2016

Ultra-high pressure positive displacement pump can discharge high pressure water with mass volume, which depends on periodic changes in volume that made by rotation motor. Its high efficiency of discharge is one of the most strong point of positive displacement pump. Due to its simple system structure, it can be miniaturized and lightened. Positive displacement pump can discharge high pressure with stable flow rate, irrespective of pressure fluctuate. This is the reason that positive displacement pump was used instead of centrifugal pump. In this study, shutoff operating system was developed for positive displacement pump to secure safety of high pressure operate. This shutoff system contains controller system, electronic clutch, and relief valve, and each part is mutual supplementation. Speed test was carried out in order to check operation of controller program and electronic clutch and fluid flow, venting experiment of the relief valve. It was confirmed that segment system of ultra-high pressure positive displacement pump is operated.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.153-162
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• 2005

Through a preliminary design process, four design candidates for a 1.4MW class partial admission turbine have been chosen and the numerical analyses using a frozen rotor method are applied to estimate their performance. Each flow analysis result was compared with others and the optimum design was selected. Flow characteristics in the passages and some types of losses induced by shocks and wakes were found from calculation results. A new rotor blade was redesigned based on these calculations and this result is compared with previous one through flow analysis.

• Journal of Power System Engineering
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• v.3 no.4
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• pp.28-35
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• 1999

An application of scroll compressor to the residential air conditioning and heat pump markets has generated many reliability problem, especially abnormal noise. Most of these noise problems is due to the check valve and compliance between FS(Fixed Scroll) and OS(Orbiting Scroll). FS and OS are the main parts of scroll compressor and are the main pumping part. But check valve has the role of protection of reverse rotation of OS when power is off. Check valve have several noise problems. Among them, shut down noise and valve movement noise is more than severe than any other problem. In this paper covers with these two noise problem.