• Tribology and Lubricants
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• v.25 no.3
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• pp.150-156
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• 2009

Precise leakage prediction for annular type seals of turbomachinery is necessary for enhancing their efficiency and various prediction methods have been developed. As the seal passage is designed intricately, the analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage is limited. In order to improve the seal leakage prediction, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved. In this study, 3D CFD (Computational Fluid Dynamics) analysis has been performed for predicting leakage of various non-contact type anular seals using FLUENT. Compared to the results by Bulk-flow model analysis, experiment, and 2D CFD analysis, the result of 3D CFD analysis shows improvement in predicting seal leakage, especially for the parallel grooved pump seal.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.43-48
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• 2004

A screw-type centrifugal pump was manufactured to carry solids primarily and its impeller has a wide flow passage. However, the effect of flow passage shape on delay of the choke due to entrained air has not been clarified yet. Moreover, because its impeller has a particular shape, only few studies have tried to clarify the pump performance and details of internal flow pattern of that pump. For that reason, we carried out the pump performance experiment under air-water two-phase flow condition with different impeller tip clearances, pump rotational speeds and void fractions by using a small screw-type centrifugal pump designed to acquire basic data. In a general centrifugal pump, it was reported that loss of pump head from single-phase flow to the choke due to air entrainment new the best efficiency point was large. However, the loss near the best efficient point in a screw-type centrifugal pump became less than that in a general centrifugal pump.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.446-453
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• 1997

The superconducting winding in rotor of a superconducting generator should be kept at extremely low temperature of 4-5 K to maintain the superconducting state. For this purpose the liquefied helium is used for the coolant and it is very important to analyze and design a cooling system making effective use of the coolant. In this paper, the typical heat exchanger of a superconducting generator with the flow passage is analyzed with regard to the thermal equilibrium. An experimental constant relevant to the flow condition in the flow passage is determined with heat exchange experiments in cryostat. Also a new heat exchanger with porous material is proposed and designed. Results of the numerical analysis for the temperature distributions for the torque tube and the coolant are reported and the efficiency of the heat exchanger is discussed from the viewpoint of amounts of coolant needed.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.79-86
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• 1998

The purpose of this paper is to examine the validation to passage of high speed train on conventional railway bridges. The dynamic behavior of bridge is analyzed by using the developed 3-D program. The train is assumed to moving loads and track to distributed masses. The centrifugal force due to curved track is also considered. The numerical results are compared with those measured in the site to demonstrate the efficiency of the developed program. From the parametric study, it is notified that conventional bridge gives good serviceability to passage of high speed train, specially such as TGV-K.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.381-385
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• 2009

This paper describes performance characteristics of a centrifugal fan having a different volute casing. The centrifugal fan has a backward blade type, and is used in a refuse collecting system. The flow characteristics inside the components are analyzed by three-dimensional Navier-Stokes analysis, and also compared to the results by experiments. Distributions of pressure and efficiency obtained by numerical simulation has a good agreement with the experimental results. Throughout the numerical simulation of the centrifugal fan, a fan efficiency is increased by decreasing local losses in the blade passage. It is found that the fan efficiency is enhanced by decreasing the distance between the shroud of a impeller and casing. Detailed flow analysis is also analyzed and discussed using the results obtained by numerical simulation.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.408-416
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• 2016

This study designed a ship energy efficiency monitoring system based on a ship application system that provides maritime services by utilizing data collected onboard, and a ship-land integration system for integrated management and exchange of maritime data. The ship energy efficiency monitoring system was developed as a Windows application program and designed to use file based EDI communications. Its main functions include route planning to minimize fuel consumption, monitoring of energy consumption and gas emissions, analysis of ship energy efficiency and other data analysis. The system has been successfully implemented in actual ships.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.491-497
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• 2002

In the present study, a new wood boiler was developed through the performance test. The efficiency of the boiler was obtained up to about 63.7%, which is 67% higher than that of conventional wood boiler, about 38.2%. The structure of the new boiler is more complicated than the conventional boiler. The passage of combustion gas is sufficiently long to exchange heat well with heating water. Therefore, the obtained efficiency is so high, and the temperature of exhaust gas was lower than 200$^{\circ}C$, which is as low as that of light oil boiler. The composition of exhaust gas was measured, and the CO gas concentration was obtained more than 3000 ppm. So, it seems that more study is needed to lower the concentration of CO gas.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.525-532
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• 2005

Shape optimization of a transonic axial compressor rotor operating at the design flow condition has been performed using response surface method and three-dimensional Navier-Stokes analysis. Three design variables of blade sweep. lean and skew are introduced to optimize the three-dimensional stacking line of the rotor blade. The object function of the shape optimization is selected as an adiabatic efficiency. Throughout the shape optimization of the rotor. the adiabatic efficiency is increased by reducing the tub comer and tip losses. Separation line due to the interference between a passage shock and surface boundary layer on the blade suction surface is moved downstream for the optimized blade compared to the reference one.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.867-872
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• 2009

In centrifugal oil filters particles are forced to move toward the filter casing wall by centrifugal force in the rotating oil flow and the particles are trapped and removed on the filter paper installed at the wall. In the present study, flow field of oil and particle motion in a centrifugal oil filter has been numerically calculated in order to estimate the filtering efficiency for various operating conditions. Fluent code was used for the numerical calculations. Uncoupling the oil flow and the particle motion and the use of particle tracking trajectory enabled the estimation of filtering efficiency for various particle sizes, particle density and the filter rotational speed. Higher filtering efficiency was observed for heavier and larger particles as well as higher filter rotational speed. For the typical case of the particle density of $6000kg/m^3$ and the particle size of $10{\mu}m$ at 3500 RPM, the calculated filtering efficiency per passage was 0.31.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.325-333
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• 2001

The present study investigates convective heat/mass transfer and flow characteristics inside the cooling passage of the gas-turbine blades. It is important to increase not only the heat transfer rates but also the uniformity of heat transfer in the cooling passage. The square duct has compound-angled ribs with $60^{\circ},\;70^{\circ}$ and $90^{\circ}$ attack angles, which are installed on the test plate surfaces. a naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. The ribs disturb the main flow resulting in the recirculation and secondary flows near the ribbed wall and the vertices near the side-wall. The local heat transfer and the secondary flow in the duct are changed largely according to the rib orientation. Therefore, geometry and arrangement of the ribs are important fur the advantageous cooling performance. The angled ribs increase the heat transfer discrepancy between the wall and center regions because of the interaction of the secondary flows. The average heat/mass transfer coefficient and pressure drop of the ribs with the $60^{\circ}$ $-90^{\circ}$ compound-angle are higher than those with the $60^{\circ}$ attack angle. Also, the thermal efficiency of the compound-angled rib is higher than that with the $60^{\circ}$ attack angle. The uniformity of heat/mass transfer coefficient on the cross ribs may is higher than that on the parallel ribs array.