• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.376-385
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• 2016

A hexagonally arrayed 37-pin wire-wrapped rod bundle has been chosen to provide the experimental data of the pressure loss and flow rate in subchannels for validating subchannel analysis codes for the sodium-cooled fast reactor core thermal/hydraulic design. The iso-kinetic sampling method has been adopted to measure the flow rate at subchannels, and newly designed sampling probes which preserve the flow area of subchannels have been devised. Experimental tests have been performed at 20-115% of the nominal flow rate and $60^{\circ}C$ (equivalent to Re ~ 37,100) at the inlet of the test rig. The pressure loss data in three measured subchannels were almost identical regardless of the subchannel locations. The flow rate at each type of subchannel was identified and the flow split factors were evaluated from the measured data. The predicted correlations and the computational fluid dynamics results agreed reasonably with the experimental data.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.1-7
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• 2007

Based on the eigenfunction expansion method, the wave-absorbing performance of a square or circular pile breakwater was investigated. Flow separation resulting from sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of an exact energy loss coefficient is critical to enhancing the reliability of the mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code, and the energy loss coefficient can be obtained from the pressure difference between upstream and downstream. It was found that energy loss coefficient of circular pile is 20% that of a square pile. To validate the fitting equation for the energy loss coefficient, comparison between the analytical results and the experimental results (Kakuno and Liu, 1993) was made for square and circular piles with good agreement. The array of square piles also provides better wave-absorbing efficiency than the circular piles, and the optimal porosity value is near P=0.1.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.731-734
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at circular manholes are usually not significant. However, the energy loss at manholes, often exceeding the friction loss of pipes under surcharge flow, is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharge flow. Hydraulic experimental apparatus with two circular manholes was installed for this study. The range of the experimental discharges were from $1.0\ell/sec$ to $4.4\ell/sec$. Head loss coefficient was maximum because of strong oscillation of water surface when the range of manhole depth ratios$(h_m/D_{in})$ were from 1,2 to 1.25. The average head loss coefficients for upstream manhole and downstream manhole were 0.58 and 0.23 respectively. Head loss at upstream manhole is nearly 2.5 times more than one at downstream manhole.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.421-426
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• 2009

This paper describes on energy loss in a pipe of refuse collecting system. Analysis energy loss in a pipe is the decisive factor in a design for refuse collecting system. From the analysis energy loss, we can determine the capacity of turbo blower. The flow characteristics in the pipe with the refuse bag are analyzed by three-dimensional Navier-Stokes analysis. The refuse bag is modeled using the actual measurement. We obtain friction factor by changing refuse bag's size and mixing ratio and Reynolds number. And From the result we calculate energy loss by using compressible flow analysis.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.619-625
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at square manholes is usually not significant. However, the energy loss at surcharged manholes is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharged flow. Hydraulic experimental apparatus which can change the manhole inner profile(CASE I, II, III, and IV) and the invert types(CASE A, B, C) were installed for this study. The experimental discharge was $16{\ell}/sec$. As the ratio of b/D(manhole width/inflow pipe diameter) increases, head loss coefficient increases due to strong horizontal swirl motion. The head loss coefficients for CASE I, II, III, and IV were 0.46, 0.38, 0.28 and 0.37, respectively. Side covers increase considerably drainage capacity at surcharged square manhole when the ratio of d/D(side cover diameter/inflow pipe diameter) was 1.0. The head loss coefficients for CASE A, B, and C were 0.45, 0.37, and 0.30, respectively. Accordingly, U-invert is the most effective for energy loss reduction at surcharged square manhole. This head loss coefficients could be available to evaluate the urban sewer system with surcharged flow.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.118-127
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• 1996

Flow patterns of fluid flow in dividing trbe were visualized, and the energy losses due to dividing were measured in laminar dividing flow of the viscoelastic fluid and its solution in tube junctions with dividing angles of $90^{\circ}$, $60^{\circ}$, $65^{\circ}$ and $15^{\circ}$. Two separation zones were observed. swelling of the streamline to the main tube or to lateral tube was observed. The sizes of the separation zones depend on the Reynolds number, the dividing angle and the dividing flow rate. The energy loss coefficients decrease with increasing Reynolds number, but their decreasing rate decreases with increasing Reynolds number as the sizes of the separation zone increase. The effect of dividing angle on the energy loss coefficients and separation is greater for main tube than for the lateral tube.

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.1-14
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• 1997

The characteristics of the flow and energy conversion in OMACON liquid-metal MHD system are investigated. Numerical simulation of two-phase flow in the OMACON system without magnetic field was carried out by the Phoenics code and the energy conversion characteristics are studied in association with the fact that the mechanical energy loss at the nozzle of the OMACON system are to be converted into electrical energy. In this system, working fluid (gas) is injected through the mixer located at the bottom of the riser, and is mixed with hot liquid metal. Therefore in the riser two-phase flow is developed under the influence of the gravity. In this study, the interaction between the gas and liquid is considered by the use of IPSA(InterPhase Slip Algorithm) where standard drag coefficient has been used. It has been assumed that in the flow regime the liquid is continuous and the gas is dispersed. For the liquid and gas, the continuity equations, momentum equations and energy equations are solved respectively in association with void fraction in the flow field. In order to calculate the energy conversion efficiency, firstly the ratio of the mechanical energy loss of liquid metal flow at the nozzle to the input thermal energy is considered. Secondly flow pattern of liquid metal in the generator has been analyzed, and the characteristics of the conversion of the mechanical energy into the electrical energy has been investigated. For an representative case where Hartmann number is 540 and magnetic field is 0.35 T, the present analysis shows that the energy conversion efficiency is 0.653. This result is considered to be reasonable in comparison with published experimental results.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4E
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• pp.164-169
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• 2002

This paper proposes a hybrid method for vibration analysis in the medium to high frequency ranges using Power Flow Analysis (PFA) algorithm and Statistical Energy Analysis (SEA) coupling concepts. The main part of the developed method is the application of coupling loss factor (CLF) suggested in SEA to the power transmission, reflection coefficients in PI' A boundary conditions. The developed hybrid method shows very promising results with regard to the applications for the various damping loss factors in wide frequency ranges. And also this paper presents the applied results of Power Flow Finite Element Method (PFFEM) by forming the new joint element matrix with CLF to analyze the various plate structures in shape. The analytical results of automobile, complex plate structures show good agreement with those of PFFEM using the PFA coefficients.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.164-164
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• 2002

This paper proposes a hybrid method for vibration analysis in the medium to high frequency ranges using Power Flow Analysis (PFA) algorithm and Statistical Energy Analysis (SEA) coupling concepts. The main part of the developed method is the application of coupling loss factor (CLF) suggested in SEA to the power transmission, reflection coefficients in PI' A boundary conditions. The developed hybrid method shows very promising results with regard to the applications for the various damping loss factors in wide frequency ranges. And also this paper presents the applied results of Power Flow Finite Element Method (PFFEM) by forming the new joint element matrix with CLF to analyze the various plate structures in shape. The analytical results of automobile, complex plate structures show good agreement with those of PFFEM using the PFA coefficients.

• Tunnel and Underground Space
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• v.6 no.1
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• pp.64-68
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• 1996

Analyzed in this paper is fluid flow in the region near the exhaust and blower ports of the ventilation ducts inside a vehicle tunnel. Theoretical analysis shows that prediction of the energy loss in this region is important for designing the ventilation system. A finite-difference numerical model for the two-dimensional turbulent flow field was used to obtain the flow solution as well as the energy loss. It was shown that the blower-nozzle angle ($\beta$) had an important role in establishing both the pressure gradient and the energy loss, while the effect of the distance between two ports on them was not so significant.