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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
Editor in Chief :
Volume & Issues
Volume 21, Issue 12 - Dec 1997
Volume 21, Issue 11 - Nov 1997
Volume 21, Issue 10 - Oct 1997
Volume 21, Issue 9 - Sep 1997
Volume 21, Issue 8 - Aug 1997
Volume 21, Issue 7 - Jul 1997
Volume 21, Issue 6 - Jun 1997
Volume 21, Issue 5 - May 1997
Volume 21, Issue 4 - Apr 1997
Volume 21, Issue 3 - Mar 1997
Volume 21, Issue 2 - Feb 1997
Volume 21, Issue 1 - Jan 1997
Selecting the target year
An experimental study on heat transfer characteristics of a rapid cooling process by twin-roll
Park, Seung-Un ; Kim, Gi-Un ; Kim, Yu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1245~1253
DOI : 10.22634/KSME-B.1918.104.22.1685
An Experimental investigation was carried out to examine the heat transfer characteristics of rapid cooling process by Twin-Roll. The experimental results were compared with numerical solutions. The measured temperature showed the about 3 % difference to the calculated results. But the cooling rate estimated by the microstructure interpretation method has much difference to the calculated results.
A study on the pulse boiling occurring inside the liquid pool of a closed two-phase thermosyphon
Kim, Cheol-Ju ; Mun, Seok-Hwan ; Gang, Hwan-Guk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1254~1261
DOI : 10.22634/KSME-B.1922.214.171.1244
Pulse boiling, the unsteady periodic boiling phenomenon appearing in the evaporator of thermosyphons was investigated by many researchers. In the present study investigations were conducted to examine the evolution of flow patterns at the evaporator, and changes in thermodynamic state that each of liquid pool and vapor experiences through 1 cycle of pulse boiling process. For wall and liquid pool the degree of superheat for the onset of nucleation was examined. It revealed that the degree of superheat increased with the increase of pulse period, reaching to 16.5 deg.C and 23 deg.C for liquid pool and evaporator wall respectively at .tau.=80 sec. The data on flow patterns obtained through series of operation tests were plotted in the coordinates of heat flux and vapor pressure to get a regime map. Further this map could be used to figure out the conditions of pulse boiling for a thermosyphon.
A study of frequency control of an inverter heat pump for indoor air temperature adjustment
Park, Yun-Cheol ; Min, Man-Gi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1262~1272
DOI : 10.22634/KSME-B.19126.96.36.1992
An experimental study on the frequency control of an inverter heat pump to get the desired indoor room temperature has been conducted for the performance characteristics during the steady, 4, 8, and 16 step frequency operations. The heat pump model used in this study was operated to meet the experimental conditions of ASHRAE standard. The performance of the system was tested by measuring the temperature and pressure of the refrigerant, and cooling capacity, power consumption, etc. of the system. As the controlling frequency steps increased, the running time of the compressor increased as well as the electric consumption of the system and the cooling energy due to the wall heating load. However, the average cooling COP was improved.
Effect of flow bleed on shock wave/boundary layer interaction
Kim, Hui-Dong ; ; Matsuo, Kazuyasu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1273~1283
DOI : 10.22634/KSME-B.19188.8.131.523
Experiments of shock wave/turbulent boundary layer interaction were conducted by using a supersonic wind tunnel. Nominal Mach number was varied in the range of 1.6 to 3.0 by means of different nozzles. The objective of the present study is to investigate the effects of boundary layer flow bleed on the interaction flow field in a straight tube. Two-dimensional slits were installed on the tube walls to bleed the turbulent boundary layer flows. The bleed flows were measured by an orifice. The ratio of the bleed mass flow to main mass flow was controlled within the range of 11 per cent. The wall pressures were measured by the flush mounted transducers and Schlieren optical observations were made for almost all of the experiments. The results show that the boundary layer flow bleed reduces the multiple shock waves to a strong normal shock wave. For the design Mach number of 1.6, it was found that the normal shock wave at the position of the silt was resulted from the main flow choking due to the suction of the boundary layer flow.
Analysis on particle deposition onto a heated, horizontal free-standing wafer with electrostatic effect
Yoo, Kyung-Hoon ; Oh, Myung-Do ; Myong, Hyon-Kook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1284~1293
DOI : 10.22634/KSME-B.19184.108.40.2064
The electrostatic effect on particle deposition onto a heated, Horizontal free-standing wafer surface was investigated numerically. The deposition mechanisms considered were convection, Brownian and turbulent diffusion, sedimentation, thermophoresis and electrostatic force. The electric charge on particle needed to calculate the electrostatic migration velocity induced by the local electric field was assumed to be the Boltzmann equilibrium charge. The electrostatic forces acted upon the particle included the Coulombic, image, dielectrophoretic and dipole-dipole forces based on the assumption that the particle and wafer surface are conducting. The electric potential distribution needed to calculate the local electric field around the wafer was calculated from the Laplace equation. The averaged and local deposition velocities were obtained for a temperature difference of 0-10 K and an applied voltage of 0-1000 v.The numerical results were then compared with those of the present suggested approximate model and the available experimental data. The comparison showed relatively good agreement between them.
Experimental study of compression waves propagating into two-continuous tunnels
Kim, Hui-Dong ; Heo, Nam-Geon ; Setoguchi, Toshiaki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1294~1302
DOI : 10.22634/KSME-B.19220.127.116.114
For the purpose of investigating the impulsive noise at the exit of high-speed railway tunnel and the pressure transients inside the tunnel, experiments were carried out using a shock tube with an open end. A great deal of experimental data were obtained and explored to analyze the peak pressures and maximum pressure gradients in the pressure waves. The effects of the distance and cross-sectional area ratio between two-continuous tunnels on the characteristics of the pressure waves were investigated. The peak pressure inside the second tunnel decreases for the distance and cross-sectional area ratio between two tunnels to increase. Also the peak pressure and maximum pressure gradient of the pressure wave inside the second tunnel increase as the maximum pressure gradient of initial compression wave increases.
Micro-macroscopic analysis on the directional casting of a metal alloy
Yu, Ho-Seon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1303~1313
DOI : 10.22634/KSME-B.1918.104.22.1683
A micro-macroscopic analysis on the conduction-controlled directional casting of Al-Cu alloys is performed, in which emphases are placed on the microstructural features. In order to facilitate the solution procedure, an iterative micro-macroscopic coupling algorithm is developed. The predicted results show that the effect of finite back diffusion on the transient solidification process in comparison with the lever rule depends essentially on the initial concentration of an alloy. In the final casting, the eutectic fraction is distributed in an increasing-decreasing-increasing pattern, each mode of which is named the chill, interior and end zones. This nonuniformity per se suffices to justify the necessity of this work because it originates from the combined effects of finite back diffusion and cooling path-dependent nature of the eutectic formation. As the cooling rate is enhanced, not only the influence depths of boundaries narrow, but also the eutectic fractions in the chill and interior zones increase. In addition, it is revealed for the first time that the micro segregation band is formed in response to a sudden change in cooling rate during the directional casting. An increasing change creates an overshooting band in the eutectic fraction distribution, and vice versa.
An investigation on heat transfer effects of two dimensional plane jet attaching offseted obliqued wall
Yun, Sun-Hyeon ; Lee, Dae-Hui ; Sim, Jae-Gyeong ; Song, Heung-Bok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1314~1325
DOI : 10.22634/KSME-B.1922.214.171.1244
Experiments have been conducted to determine the flow and heat transfer characteristics for a two-dimensional turbulent wall attaching offset jet at different oblique angles to a flat surface. The distributions of the wall static pressure coefficient and time-averaged reattachment position for various offset ratios and oblique angles have been measured. The local Nusselt number distributions on the plate surface were also measured using liquid crystal as a temperature indicator. The new hue-capturing technique utilizing a true color image processing system was used to accurately determine the temperature of the liquid crystal. The experiments were carried out at Reynolds number, Re (based on D) of from 7300 to 21,300 with offset ratio, H/D from 2.5 to 10, and oblique angle, .alpha. from 0 deg. to 400 deg..
Electrical characteristics of soot particles in a LPG diffusion flame and particle size change by electric fields
Park, Jong-In ; Ji, Jun-Ho ; Hwang, Jeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1326~1338
DOI : 10.22634/KSME-B.19126.96.36.1996
Electrical characteristics of soot particles in a LPG diffusion flame were studied for the control of soot particle coagulation. When a DC voltage was applied between two electrodes installed parallel to gas flow, ionic wind effect caused soot deposition on the cathode, implying that most of the soot particles were positively charged. Soot deposit on the cathode linearly increased and was saturated with respect to the strength of the applied voltage. The possibility of applying an AC voltage to enhance the particle coagulation was then investigated and the efficiency of the size control was checked with transmission electron microscope photographs. For the amplitude of 2 kV AC field, primary (spherical) soot particle size decreased from 30 ~ 40 nm to around 20 nm when the frequency of the applied AC voltage was 60 Hz and higher. Collisions between the soot particles in such a selected AC condition could lead to the formation of much bigger agglomerates of roughly 1-5 .mu.m in size.
Performance analysis of a scroll compressor considering quasi one-dimensional leakage modeling and heat transfer loss
Gang, Tae-Gyu ; Park, Gyeong-U ; Jeong, Yeon-Gu ; Park, Hui-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1339~1349
DOI : 10.22634/KSME-B.19188.8.131.529
A numerical method of calculating the performance of a scroll compressor for refrigerant R-22 and R-134a is presented in this paper. A series of involute curves are employed for the scroll wrap design and the compression volume is investigated geometrically. The radial leakage flow rate through tip clearance is calculated by the two-dimensional compressible flow. On the basis of the results, quasi one-dimensional leakage modeling can be applied to the performance analysis of a scroll compressor, more effectively. Furthermore, the heat transfer effect between scroll wrap and working fluid in compression chamber is considered for the performance analysis. As the results of this study, the effects of the radial and tangential leakage flow rate and heat transfer on the scroll compressor performance are derived precisely. These results may provide the guideline for the design and development of a real scroll compressor.
Vortex pairing in an axisymmetric jet using fundamental and subharmonic forcing
Jo, Seong-Gwon ; Yu, Jeong-Yeol ; Choe, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1350~1362
DOI : 10.22634/KSME-B.19184.108.40.2060
An experimental study has been performed on vortex pairing under fundamental and subharmonic forcing with controlled initial phase differences through hot-wire measurements and a multi-smoke wire flow visualization. For the range of St
< 0.6, vortex pairing was controlled by means of fundamental and subharmonic forcing with varying initial phase differences. Much larger mixing rate was achieved by two-frequency forcing with a proper phase difference than one frequency forcing. As St
decreased, vortex pairing was limited to a narrow region of the initial phase difference between two disturbances and higher amplitudes of the fundamental and its subharmonic at the nozzle exit were required for more stable pairing. As the amplitude of the subharmonic at the nozzle exit increased for fixed St
and fundamental amplitude, the distribution of the subharmonic mode against the variation of the initial phase difference changed from a sine function form into a cusp-like form. Thus, vortex pairing can be controlled more precisely for the former case. For St
> 0.6, non-pairing advection of vortices due to the improper phase difference was sometimes observed in several fundamental forcing amplitudes when only the fundamental was applied. However, when its subharmonic was added, vortex pairing readily occurred. As the initial amplitude of this subharmonic increased, the position of vortex pairing moved upstream. This was thought to be due to the fact that the variation of the initial phase difference between the fundamental and its subharmonic has less effects on vortex pairing in the region of fundamental-only vortex pairing.pairing.
Investigation of a droplet combustion with nongray gas radiation effects
Choe, Chang-Eun ; Park, Jae-Hyeon ; Park, Seung-Uk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1363~1370
DOI : 10.22634/KSME-B.19220.127.116.113
Single liquid droplet combustion processes including heating, evaporation, droplet burning and flame radiation were theoretically investigated by adopting nongray gas radiation model for the radiative transfer equation (RTE). n-Heptane was chosen as a fuel and the numerical results were compared with the experimental data available in the literature. The discrete ordinate method (DOM) was employed to solve the radiative transfer equation and the weighted sum of gray gases model (WSGGM) was applied to account for nongray effect by CO
, and H
0. Therefore, detailed effects by nongray gas and its comparison with the gray gas model could be figured out in the results. It is found that the radiative heat flux is higher when the nongray model is used, thereby reducing the maximum gas temperature and the flame thickness, but the total burning time increases due to the deceased conductive heat flux in nongray model. Consequently, a better agreement with experimental data could be obtained by using nongray model.
Experimental study on the discharge coefficients and cavitation of conical orifices
Kim, Byeong-Chan ; Yun, Byeong-Ok ; Park, Bok-Chun ; Jo, Nam-O ; Ji, Dae-seong ; Jeong, Baek-Sun ; Park, Gyeong-Am ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1371~1379
DOI : 10.22634/KSME-B.1918.104.22.1681
The high pressure drop is frequently required in the by-pass line of the pump or of the heat exchanger in power plants. However, cavitation produced by a high pressure drop could damage the pipe and pump blades. Conical orifices are adopted to reduce cavitation due to high pressure drop. The discharge coefficients of conical orifice plates were measured by weighing method in the standard water flow system. The discharge coefficients were larger when the ratios of thickness of orifice edge to throat diameter were larger. The noise generated from a conical orifice due to cavitation was measured with a sound level meter and a hydrophone. With increasing the bore diameter of the orifice, the sound pressure level or the noise level due to cavitation became higher. The noise level was suddenly increased at the inception of cavitation.
System design of an air-cooled 3-stage reciprocating air compressor and performance testing
Lee, An-Seong ; Kim, Yeong-Cheol ; Jeong, Yeong-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 10, 1997, Pages 1380~1391
DOI : 10.22634/KSME-B.1922.214.171.1240
A 150 m
/hr, 30 kg/cm
, air-cooled 3-stage reciprocating air compressor is designed to be used in starting large diesel engines. A basic design procedure is presented to meet the targeted pressure and flow rate, and especially the volumetric efficiency. Temperature and stress analyses of the cylinder are performed using FEM modelings. The dynamics of valve system is analyzed and stress at the valve seat due to valve impact is evaluated. To reduce friction loss and wear at the compressor engine system, tribological design practices are suggested. Fin-type coolers are designed to dissipate generated compression heat at each stage. Finally, a prototype is manufactured and performance test is carried out utilizing an air tank. Performance results are compared to the design targets, other foreign specifications, and some quality standards.