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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 24, Issue 12 - Dec 2000
Volume 24, Issue 11 - Nov 2000
Volume 24, Issue 10 - Oct 2000
Volume 24, Issue 9 - Sep 2000
Volume 24, Issue 8 - Aug 2000
Volume 24, Issue 7 - Jul 2000
Volume 24, Issue 6 - Jun 2000
Volume 24, Issue 5 - May 2000
Volume 24, Issue 4 - Apr 2000
Volume 24, Issue 3 - Mar 2000
Volume 24, Issue 2 - Feb 2000
Volume 24, Issue 1 - Jan 2000
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An Experimental Study on the Flow Stabilization in the Downstream Region of a Butterfly-Type Valve
Park, Sang-Won ; Lee, Sang-U ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1417~1427
DOI : 10.22634/KSME-B.2000.24.11.1417
A flow stabilizer, which is made of a honeycomb and three different mesh screens, is located downstream of a butterfly-type valve, for the reduction of flow disturbances behind the valve. Mean flow and turbulence measurements as well as flow visualizations are conducted in the downstream region of the deepens the non-uniformity of the streamwise velocity component and turbulence. The mesh screens considerably reduce the turbulence and enhance the uniformity of mean velocities. The combination of the honeycomb and the three mesh screens results in an efficient reduction in the flow disturbances. In addition, the flow stabilizer proves to have a good performance in the suppression of turbulence at a short distance.
Analysis of Heat and Mass Transfer on Helical Absorber
Gwon, O-Gyeong ; Im, Jong-Geuk ; Yun, Jeong-In ; Kim, Seon-Chang ; Yun, Jae-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1428~1436
DOI : 10.22634/KSME-B.2000.24.11.1428
The absorption of vapor involves simultaneous heat and mass transfer in the vapor/liquid system. In this paper, a numerical study for vapor absorption process into LIBr-H
O solution film flowing over helical absorber has been carried out. Axisymmetric cylindrical coordinate system was adopted to model the helical tube and the transport equations were solved by the finite volume method. The effects of operating conditions, such as the cooling water temperature. the system pressure, the film Reynolds number and the solution inlet concentration have been investigated in view of the absorption mass flux and the total absorption mass flux and the total absorption rate. The results for the temperature and concentration profiles, as well as the local absorption mass flux at the helical absorber are presented. It is shown that solution inlet concentration affected other than operation conditions for a mass flux.
A Numerical Analysis on the Freeze Coating of a Non-Isothermal Flat Plate with a Binary Alloy
Nam, Jin-Hyeon ; Kim, Chan-Jung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1437~1446
DOI : 10.22634/KSME-B.2000.24.11.1437
A numerical analysis on the freeze coating process of a non-isothermal finite dimensional plate with a binary alloy is performed to investigate the growth and decay behavior of the solid and the mushy layer of the freeze coat and a complete procedure to calculate the process is obtained in this study. The continuously varying solid and mushy layers are immobilized by a coordinate transform and the resulting governing differential equations are solved by a finite difference technique. To account for the latent heat release and property change during solidification, proper phase change models are adopted. And the convection in the liquid melt is modeled as an appropriate heat transfer boundary condition at the liquid/mushy interface. The present results are compared with analytic solutions derived for the freeze coating of infinite dimensional plates and the discrepancy is found to be less than 0.5 percent in relative magnitude for all simulation cases. In addition the conservation of thermal energy is checked. The results show that the freeze coat grows proportional to the 1.2 square of axial position as predicted by analytic solutions ar first. But after the short period of initial growth, the growth rate of the freeze coat gradually decreases and finally the freeze coat starts to decay. The effects of various non-dimensional processing parameters on the behavior of freeze coat are also investigated.
Simulated Experiments on High Pressure Melt Ejection in the Reactor Cavity During Severe Accident
Jeong, Han-Won ; Kim, Do-Hyeong ; Lee, Gyu-Jeong ; Kim, Sang-Baek ; Park, Rae-Jun ; Kim, Hui-Dong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1447~1456
DOI : 10.22634/KSME-B.2000.24.11.1447
Simulated experiments of high pressure melt ejection(HPME) are performed to measure the released fraction of corium simulant from the French type PWR cavity. The experiments are carried out on a 1/20th linear scaled model of the Ulchin 1&2 cavity. Water or woods metal and nitrogen is used as simulant of molten corium and steam, respectively. Experimental parameters are water mass, annulus area and breach size. It is shown that only breach size effects is very important while the mass and the annulus area do not affect the released fraction. It is found that the liquid film transport is much more dominant mechanism than the entrainment droplet transport, especially in linear scale down simulated HPME experiment.
A Study on Ignition Characteristic with Supply Leading Time of Propellants in Liquid Rocket Engine
Park, Jeong ; Kim, Yong-Uk ; Kim, Yeong-Han ; Lee, Jae-Ryong ; Jeong, Yong-Gap ; Jo, Nam-Gyeong ; O, Seung-Hyeop ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1457~1463
DOI : 10.22634/KSME-B.2000.24.11.1457
Experimental studies on determination of the supply leading time of propellants to combustion chamber have been made to stably and efficiently guarantee the ignitions process with liquid rocket engine. The propellant used is a Kerosene as fuel and a liquid oxygen as oxidizer. FOOF type of three injectors are set with an angle of 135。 and the combustion chamber pressure is 200psi. The present experiment program also includes the stability on the quadlet type of ignitor using the triehylaluminum (TEAL) as an ignition source. Experimental results clarifies that the propellant supply through LOx leading to combustion chamber is proper for stable ignition and combustion processes based on the fuel and oxidizer manifold pressures, combustion chamber pressure, and the variation of flame length from the nozzle exit with lapse time, and shows that the leading supply time pf propellants effects the engine performance little.
Measurements of Temperature and OH Radical Distributions in Flame Hydrolysis Deposition Process
Hwang, Jun-Yeong ; Gil, Yong-Seok ; Kim, Jeong-Ik ; Choe, Man-Su ; Jeong, Seok-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1464~1469
DOI : 10.22634/KSME-B.2000.24.11.1464
The effects of SiCl
addition on flame structures have been studied in flame hydrolysis deposition (FHD) processes using Coherent anti-Stokes Raman spectroscopy (CARS) and planar laser induced fluorescence (PLIF) to measure temperatures and OH concentrations, respectively. The results demonstrate that even a small amount of SiCl
addition can change thermal and chemical structures of H
diffusion flames. When SiCl
is added to a flame temperature decreases in non-reacting zone due to the increases in both specific heat and density of the gas mixture, while flame temperature increase in particle formation zone due to the heat release through hydrolysis and oxidation reactions of SiCl
. It is also found that OH concentration decreases dramatically in particle formation zone where temperatures increase. This can be attributed to consumption of oxidative species and generation of HCl during silica formation.
Experiments on Condensation Heat Transfer Characteristics Inside a Microfin Tube with R410A
Han, Dong-Hyeok ; Jo, Yeong-Jin ; Lee, Gyu-Jeong ; Park, Sim-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1470~1477
DOI : 10.22634/KSME-B.2000.24.11.1470
Due to the ozone depletion and global warming potentials, some refrigerants(CFx and HCFCs) have been rapidly substituted. R410A is considered as the alternative refrigerant of R22 for the air-conditioners used a home and in industry. Experiments on the condensation heat transfer characteristics inside a smooth or a micro-fin tube with R410A are performed in this study. The test tubes 7/9.52 mm in outer diameters and 3 m in length are used. Varying the mass flux of the refrigerant and the condensation temperatures, the average heat transfer coefficients and pressure drop are investigated. It is shown that the heat transfer is enhanced and the amount of pressure drops are larger in the microfin tube than the smooth tube. From the heat transfer enhancement coefficient and the pressure penalty factor, it is found that the high heat transfer enhancement coefficients are obtained in the range of small mass flux while the penalty factors are almost equal.
An Experimental Study of Fouling Effect on the Heat Transfer Around a Tube in Staggered Tube Banks
Kim, Min-Su ; Baek, Byeong-Jun ; Park, Bok-Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1478~1485
DOI : 10.22634/KSME-B.2000.24.11.1478
An experimental study has been performed to investigated the forced convection heat transfer characteristics of 6 circular cylinders in staggered arrangement in a cross flow of air. The water scale deposited on condenser wall of power plant was used to investigate the effect of roughness of scaled surfaces. The relative roughness*average diameter of scale/cylinder diameter) was in a range of k/d=0.0066, 0.0111, 0.0167, 0.0222 and 0.0278. The cylinder spacings(L/d) varies from 1.5 to 4.0 where L denote the cylinder spacings along and normal to the upstream uniform flow direction. The Reynolds number was varied in a range of 10, 000
50,000. The local and mean Nusselt numbers were investigated as a function of scale roughness, the cylinder spacing and Reynolds number. The results are compared with those of clean cylinder and inline tube bank, subsequently the mean fouling resistance over the entire circumference was estimated from those results as a function of scale roughness, the cylinder spacing and Reynolds number.
A Study on the Effects of Ignition Systems on the Heat Release Rate and Mass Fraction Burnt at a Constant Volume Combustion Chamber
Song, Jeong-Hun ; Lee, Gi-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1486~1496
DOI : 10.22634/KSME-B.2000.24.11.1486
The initial flame kernel development and flame propagation in a constant volume combustion chamber is analyzed by the heat release rate and the mass fraction burnt. The combustion pressure is measured with a piezoelectric type pressure sensor. In order to evaluate the effects of ignition system and ignition energy on the flame propagation, four different ignition systems are designed and tested, and the ignition energy is varied by the dwell time. Several different spark plugs are also tested and examined to analysis the effects of electrodes on flame kernel development. The results show that the when the dwell time is increased, and when the spark plug gap is extended, heat release rate and the mass burnt fraction are increased. The materials and shapes of electrodes affect the flame development, because they change the energy transfer efficiency from electrical energy to chemical energy. The diameter of electrodes influences not only the heat release rate but also the mass burnt fraction as well.
Effects of the Curvature on the Freezing Phenomena of a Laminar Water Flow in a Curved Channel
Seo, Jeong-Se ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1497~1505
DOI : 10.22634/KSME-B.2000.24.11.1497
A numerical study is made on the ice-formation for a laminar flow in a curved channel. When the water flows through the curved channel with the walls specified below the freezing temperature, the ice layer has been formed on the curved surface, different from that of a straight channel. The fluctuation of ice layer has been predicted, considering the variation of velocity and temperature near the curved portion of channel. The study also takes into account the interaction existing between the laminar flow and the curved channel. In the solution strategy, the present study is substantially different from the existing works in that the complete set of governing equations in both the solid and liquid regions are resolved. The results from this study have been mainly presented, focusing on the variation of ice layer close to the curved portion. Numerical results have been obtained parametrically by varying the curved angle and the radius of curvature of channel, in addition to the variation of Reynolds numbers and wall temperatures of channel. The results show that the curved shape of channel has the great effect on the thickness of the solidification layer. The wave of ice layer thickness appears in the vicinity of curved portion. This behavior of ice layer has been amplified as is the increasing of curved angle and the radius of curvature of channel. In addition, the ice layer becomes thin as Reynolds numbers in increasing. And also, as the wall temperature of channel increases, the width of channel becomes to be shrunk due to the growth of ice layers in the upper and lower wall of channel.
An Experimental Study on the Control of Shock in the Hydraulic Actuator System Using the Orifice
Lee, Ju-Seong ; Lee, Gye-Bok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1506~1512
DOI : 10.22634/KSME-B.2000.24.11.1506
Control of shock may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is an idealization of an automobile shift system. Control is accomplished by installing three different types of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and control level depends on the orifice size, orifice type, operating pressure and flow rate.
A Study on the Burning Velocity Correlation of LFG Mixed Fuel Using Numerical Analysis
Lee, Chang-Eon ; O, Chang-Bo ; Jeong, Ik-San ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1513~1522
DOI : 10.22634/KSME-B.2000.24.11.1513
In this study, the burning velocities of LFG and LFG mixed fuels have been numerically determined. C3 reaction mechanism involving 92 species and 621 reactions was adopted in the calculation. The computed burning velocities using C3 mechanism show good agreements with experimental data. Based on numerical results, the maximum burning velocities of LFG and LFG mixed fuels were correlated as a function of CH
and LFG component percentage at stoichiometric conditions. In addition, the correlations of burning velocities of LFG and LFG mixed fuels were obtained over a wide range of the equivalence ratio. The numerical results are well agreed with the burning velocity correlations. The burning velocity correlations for LFG and LFG mixed fuels suggested in this study can be applied to the practical utilization of LFG.
On Subgrid-Scale Models for Large-Fddy Simulation of Turbulent Flows
Gang, Sang-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1523~1534
DOI : 10.22634/KSME-B.2000.24.11.1523
The performance of a number of existing dynamic subgrid-scale(SGS) models is evaluated in large-eddy simulations(LES) of two prototype transitional and turbulent shear flows, a planar jet and a channel flow. The dynamic SGS models applied include the dynamic Smagorinsky model(DSM);Germano et al. 1991, Lully 1992), the dynamic tow-component model(DTM; Akhavan et al. 2000), the dynamic mixed model(DMM;Zang et al, 1993). and the dynamic two-parameter model(DTPM; Salvetti & Banerjee 1995). The results are compared with those for DNS for their evaluation. The LES results demonstrate the superior performance of DTM with use of a sharp cutoff filter and DMM with use of a box filter, as compared to their respect counterpart DSM, in predicting the mean statistics, spectra and large-scale structure of the flow, Such features of DTM and DMM derive from the construction of the models in which tow separate terms are included to represent the SGS interactions; a Smagorinsky edd-viscosity term to account for the non-local interactions, and a local-interaction term to account for the nonlinear dynamics between the resolved and subgrid scales in the vicinity of the LES cutoff. As well, overall the SGS models using a sharp cutoff filter are more successful than those using a box filter in capturing the statistics and structure of the flow. Finally, DTPM is found to be compatible or inferior to DMM.
Evaluation of Critical Pressure Ratios Sonic Nozzle at Low Reynolds Numbers
Choe, Yong-Mun ; Park, Gyeong-Am ; Cha, Ji-Seon ; Choe, Hae-Man ; Yun, Bok-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1535~1539
DOI : 10.22634/KSME-B.2000.24.11.1535
A sonic nozzle is used as a reference flow meter in the area of gas flow rate measurement. The critical pressure ratio of sonic nozzle is an important factor in maintaining its operating condition. ISO9300 suggested the critical pressure ratio of sonic nozzle as a function of area ratio. In this study, 13 sonic nozzles were made by the design of ISC9300 with different half diffuser angles of 2。 to 8。 and throat diameters of 0.28 to 4.48 mm. The test results of half diffuser angles below 8。 ar quite similar to those of ISO9300. On the other hand, the critical pressure ratio for the nozzle of 8。 decreases by 5.5% in comparison with ISO9300. However, ISO9300 does not predict the critical pressure ratio at lower Reynolds numbers than 10(sup)5. Therefore, it is found that it is a better way for the flow of low Reynolds number to express the critical pressure ratio of sonic nozzle as a function of Reynolds number than area ratios. A correlation equation of critical pressure is introduced with uncertainty
3.2 % at 95% confidence level.
Measurements of Secondary Vortices in the Cylinder Wake by Three-Dimensional Phase-Averaging Technique Using Cinematic PIV Data
Seong, Jae-Yong ; Yu, Jeong-Yeol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1540~1548
DOI : 10.22634/KSME-B.2000.24.11.1540
Near-wake flow field downstream of a circular cylinder in the wake-transition regime where fine-scale secondary vortices have a spanwise wavelength of around one diameter has been studied by means of phase-averaging from cinematic PIV data. A cross-correlation algorithm in conjunction with the FFT(Fast Fourier Transform)analysis and an offset correlation technique is used for obtaining the velocity vectors. Which the help of very high sampling rate compared to the shedding frequency, it is possible to obtain phase-averaged flow fields although the shedding is not forced but natural. Phase -locked three-dimensional vortical structures are reconstructed form the phase-averaged data in one x-y(cross-sectional) and several z-x(spanwise-streamwise)planes. In this process of phase-averaging in a z-x plane, a technique to freeze the secondary vortices relative to the centerline is applied. The formation process of the secondary vortices is shown by considering spatial relations between the primary Karman and the secondary vortices and their temporal evolutions.
Prediction of Billet Temperature by the Total Heat Exchange Factor on the Reheating Furnace
Gang, Deok-Hong ; Kim, Gi-Hong ; Lee, Yong-Guk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 11, 2000, Pages 1549~1554
DOI : 10.22634/KSME-B.2000.24.11.1549
A new method to determine the total heat exchange factor was proposed for the prediction of billet temperature in a reheating furnace. This method employed the squared of the difference between measured and predicted temperatures as an objective function. The real billet temperature in a walking beam type reheating furnace with 19.75m of its effective length was directly measured by thermocouples. The present method was validated by showing that the predicted billet temperature was in a good agreement with the measured one.