• Journal of ILASS-Korea
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• v.9 no.2
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• pp.18-23
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• 2004

An experimental studies of conventional gasoline fuel pump were carried out to obtain fundamental data fur liquid phase LPG injection(LPLi) system. A regenerative type and a roller-vane type of pumps were investigated in various operational condition. The experiments were performed to obtain flow rate of LPG fuel as a function of pressure differences and temperatures. The regenerative pump had too low flow rate at some experimental conditions to use this pump system for LPLi fuel supply system. On the other hand, the roller-vane type pump can be applied to the system only if its check valve is modified. Cavitation might occur in this system which can result in system noise, flow rate variation, and pump durability problem. To solve these problems the system is needed to increase $NPSH_{re}$(required net positive suction head).

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1209-1216
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• 2018

This study aimed to evaluate the antimicrobial activity of 2-phenylethynyl-butyltellurium (PEBT) in Escherichia coli and the relation to its pro-oxidant effect. For this, we carried out the disk diffusion test, minimum inhibitory concentration (MIC) assay, and survival curve analysis. We also measured the level of extracellular reactive oxygen species (ROS), activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and level of non-protein thiols (NPSH). PEBT at 1.28 and 0.128 mg/disk exhibited antimicrobial capability in the disk diffusion test, with an MIC value of 1.92 mg/ml, whereas PEBT at 0.96, 1.92, and 3.84 mg/ml inhibited bacterial growth after a 9-h exposure. PEBT at 3.84, 1.92, and 0.96 mg/ml increased extracellular ROS production, decreased the intracellular NPSH level, and reduced the SOD and CAT activities. Glutathione or ascorbic acid in the medium protected the bacterial cells from the antimicrobial effect of PEBT. In conclusion, PEBT exhibited antimicrobial activity against E. coli, involving the generation of ROS, oxidation of NPSH, and reduction of the antioxidant defenses in the bacterial cells.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.297-298
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• 2012

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.250-257
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• 2001

Low NPSH and high pressure pumps are widely used for turbopump systems, which have an inducer and operate at high rotating speeds In this paper, a meanline method has been established for the preliminary design and performance prediction of pumps having an inducer for cavitating or non-cavitating conditions and at design or off-design points. The method was applied for the performance prediction of a fuel pump, which had been developed by Hyundai Mobis in collaboration with KeRC for a liquid rocket engine. The engine uses liquid methane and liquid oxygen as working fluids and rotates at 50,000 rpm KeRC carried out a model testing of the fuel pump with water as a working fluid at the reduced speed (10,000 ${\~}$ 15,000 rpm). 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.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.341-346
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• 2004

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 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 pun was generated to improve pump performance by utilizing CFD results. The modified fuel pump was experimentally tested by ROTEM and KARI. 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.18 no.1
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• pp.65-71
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• 2015

The purpose of this study is to investigate cavitating flow of the multistage centrifugal pump. Cavitation is observed in the impeller leading edge and trailing edge of the suction area. Head coefficients are measured under different flow operating conditions. The Rayleigh-Plesset cavitation model is adapted to predict the occurrence of cavitation in the pump. The two-phase gas-liquid homogeneous CFD method is used to analyze the centrifugal pump performances with two equation transport turbulence model. The simulations are carried out with three different flow coefficients such as 0.103, 0.128 and 0.154. The occurrence of cavitation described according to water vapor volume fraction. The head versus NPSH (Net Positive Suction Head) also measured using different flow coefficients. Development of cavitation in the centrifugal pump impellerI is discussed. It is showed that the simulation represents the head drop about 3%.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.637-642
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• 2001

Performance and cavitation characteristics of a turbo pump inducer which is designed for oxygen pump is experimentally investigated. It is found that the static performance of inducer is dependent on the location of inlet pressure measurement and that enough distance from inducer is ensured for accurate evaluation of performance. With the increase of flow rate. NPSH tends to decrease as opposed to pump characteristics, which seems to be due to the cavitation region.

• Atmosphere
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• v.27 no.3
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• pp.277-290
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• 2017

Characteristics of precipitation in South Korea during the 2016 Changma period (6/18~7/30) are analyzed in great details. El $Ni{\tilde{n}}o$-induced tropical Indian Ocean (IO) basin-wide warming lasts from spring to early summer and induces the western North Pacific subtropical high (WNPSH) circulation anomaly through an equatorial Kelvin wave during the 2016 Changma period. Along the northern edge of the WNPSH, strong precipitation occurred, in particular, over eastern China and southern Japan. During the Changma period, South Korea had the near-normal mean precipitation amount (~332 mm). However, about 226 mm of rain fell in South Korea during 1 July to 6 July, which amounts to 67% of total Changma precipitation in that year. Upper-level synoptic migratory lows and low-level moisture transport played an essential role, especially from 1 July to 3 July, in triggering an abrupt development of fronts over the Korean Peninsula and the eastern continent China. The front over the eastern China migrates progressively eastward, which results in heavy rainfall over the Korean peninsula from 1 to 3 July. In contrast, from 4 to 6 July, the typhoon (NEPARTAK) affected an abrupt northward advance of the North Pacific subtropical high (NPSH). The northward extension of the NPSH strengthens the Changma front and induces the southerly flows toward the Korean peninsula, giving rise to an increase in heavy rainfall. The NEPARTAK is generated due to interaction of the Madden-Julian Oscillation (MJO), equatorial Rossby wave and Kelvin waves.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2471-2478
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• 2020

Pumps are essential machinery in the various industries. With the development of high-speed and large-scale pumps, especially high energy density, high requirements have been imposed on the vibration and noise performance of pumps, and cavitation is an important source of vibration and noise excitation in pumps, so it is necessary to improve pumps cavitation performance. The modern pump optimization design method mainly adopts parameterization and artificial intelligence coupling optimization, which requires direct correlation between geometric parameters and pump performance. The existing cavitation performance calculation method is difficult to be integrated into multi-objective automatic coupling optimization. Therefore, a fast prediction method for pump cavitation performance is urgently needed. This paper proposes a novel cavitation prediction method based on impeller pressure isosurface at single-phase media. When the cavitation occurs, the area of pressure isosurface S_iso increases linearly with the NPSH_a decrease. This demonstrates that with the development of cavitation, the variation law of the head with the NPSH_a and the variation law of the head with the area of pressure isosurface are consistent. Therefore, the area of pressure isosurface S_iso can be used to predict cavitation performance. For a certain impeller blade, since the area ratio R_s is proportional to the area of pressure isosurface S_iso, the cavitation performance can be predicted by the R_s. In this paper, a new cavitation performance prediction method is proposed, and the feasibility of this method is demonstrated in combination with experiments, which will greatly accelerate the pump hydraulic optimization design.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.382-388
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• 2004

The hydraulic and suction performance of an inducer varies sensitively with the inducer geometry and this paper deals with solidity as the inducer geometry parameter. The typical performance characteristics of a basic inducer was investigated and tests with another three inducers of which the solidity is different from each other were performed, so the effect of solidity on the inducer performance was experimentally investigated. For a fixed flow coefficient, required NPSH of the inducer did not follow the conventional similarity rule, so this paper suggested another empirical formula. The hydraulic and suction performance was measured at four cases of the tip solidity ranged from 1.32 to 2.76. As long as the tip solidity had the value above 1.84, the hydraulic and suction performance of the inducer increased with decrease in the tip solidity. With further decrease in the tip solidity up to 1.32, however, inducer head decreased and the suction performance dropped sharply.