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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 32, Issue 12 - Dec 2008
Volume 32, Issue 11 - Nov 2008
Volume 32, Issue 10 - Oct 2008
Volume 32, Issue 9 - Sep 2008
Volume 32, Issue 8 - Aug 2008
Volume 32, Issue 7 - Jul 2008
Volume 32, Issue 6 - Jun 2008
Volume 32, Issue 5 - May 2008
Volume 32, Issue 4 - Apr 2008
Volume 32, Issue 3 - Mar 2008
Volume 32, Issue 2 - Feb 2008
Volume 32, Issue 1 - Jan 2008
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Numerical Study About the Effect of the Low Reynolds Number on the Performance in an Axial Compressor
Choi, Min-Suk ; Chung, Hee-Taeg ; Oh, Seong-Hwan ; Ko, Han-Young ; Baek, Je-Hyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 83~91
DOI : 10.3795/KSME-B.2008.32.2.083
A three-dimensional computation was conducted to understand effects of the low Reynolds number on the performance in a low-speed axial compressor at the design condition. The low Reynolds number can originates from the change of the air density because it decreases along the altitude in the troposphere. The performance of the axial compressor such as the static pressure rise was diminished by the separation on the suction surface with full span and the boundary layer on the hub, which were caused by the low Reynolds number. The total pressure loss at the low Reynolds number was found to be greater than that at the reference Reynolds number at the region from the hub to 85% span. Total pressure loss was scrutinized through three major loss categories in a subsonic axial compressor such as the profile loss, the tip leakage loss and the endwall loss using Denton#s loss model, and the effects of the low Reynolds number on the performance were analyzed in detail.
Study of Energy Separation Mechanism in Vortex Tube by CFD
Choi, Won-Chul ; Chung, Myung-Kyoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 92~99
DOI : 10.3795/KSME-B.2008.32.2.092
The "energy separation phenomenon" through a vortex tube has been a long-standing mechanical engineering problem whose operational principle is not yet known. In order to find the operational principle of the vortex tube, CFD analysis of the flow field in the vortex tube has been carried out. It was found that the energy separation mechanism in the vortex tube consists of basically two major thermodynamic-fluid mechanical processes. One is the isentropic expansion process at the inlet nozzle, during which the gas temperature is nearly isentropically cooled. Second process is the viscous dissipation heating due to the high level of turbulence in both flow passages toward cold gas exit as well as the hot gas exit of the vortex tube. Since the amount of such a viscous heating is different between the two passages, the gas temperature at the cold exit is much lower than that at the hot exit.
] Emission Characteristics in Radiant Tube Burner with Oscillating Combustion Technology
Cho, Han-Chang ; Cho, Kil-Won ; Kim, Hoo-Joong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 100~106
DOI : 10.3795/KSME-B.2008.32.2.100
An experimental study was carried out in a small-scale test furnace to investigate the performance, such as
emission, enhancement of heat transfer, uniformity of temperature, and etc, of oscillating combustion applied in radiant tube burner system. A premixed type burner and a cyclic oscillating control valve were designed and used. The fuel, used commercial LPG in this study, was only oscillated using the cyclic oscillating control valve. As oscillating combustion was applied in radiant tube burner system, it is found that
emission, compared to no oscillation, could be reduced by 38% at
. However, as oscillating frequency was increased, effect of abatement of
emission is gradually reduced. From the measurement of furnace heating time from
, heat transfer is increased by 11.5% at the oscillation of 120rpm. Temperature distribution of radiant tube surface is more uniform at oscillation of 120rpm with decrease of the peak temperature and increase of low temperature. From these results, it is confirmed that oscillating combustion is useful in radiant tube burner system.
An Experimental Study on the Internal Flow Characteristics of a Jet Pump for the Smart UAV Fuel System
Lee, Yoon-Kwon ; Lee, Chang-Ho ; Choi, Hee-Joo ; Lee, Jee-Keun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 107~116
DOI : 10.3795/KSME-B.2008.32.2.107
The jet pumps are widely used to transfer the fuel between the tanks in an aircraft fuel supply system. However detailed design procedures for determining the size of components of the jet pumps are not known so well. In this paper, the flow characteristics of the jet pump, which is applied in the fuel transfer system for the smart UAV (Unmanned Aerial Vehicle), were experimentally investigated using the acrylic jet pump model for the visualization of the internal flow. The pressure distributions within the jet pump were measured, and then the loss coefficients of each part were calculated. The effects of Reynolds number and the distances (S) between the exit of the primary nozzle and the mixing chamber entrance were investigated. In addition, cavitation phenomena were considered through the flow visualization inside the jet pump. As a conclusion from the experiment, the contraction shape of the primary nozzle has a strong effect on the loss coefficient of the nozzle and the cavitation occurrence. Cavitation starts around the nozzle exit, and then it propagates to the full flow fields of the jet pump.
Measuring Convective Heat Transfer Coefficient Around a Heated Fine Wire in Cross Flow of Nanofluids
Lee, Shin-Pyo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 117~124
DOI : 10.3795/KSME-B.2008.32.2.117
Recent researches on nanofluids have mainly focused on the increase of thermal conductivity of nanofluids under static condition. The ultimate goal of using nanofluids, however, is to enhance the heat transfer performance under fluid flow. So it has been highly necessary to devise a simple and accurate measuring apparatus which effectively compares the heat transfer capability between the base and nanofluids. Though the convective heat transfer coefficient is not the complete index for the heat transfer capability, it might be one of useful indications of heat transfer enhancement. In this article, the working principles of experimental system for convective heat transfer coefficient around a heated fine wire in cross flow of nanofluids and its application example to three samples of nano lubrication oils are explained in detail.
Numerical Study of Bubble Growth and Reversible Flow in Parallel Microchannels
Lee, Woo-Rim ; Son, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 125~132
DOI : 10.3795/KSME-B.2008.32.2.125
The bubble dynamics and heat transfer associated with nucleate boiling in parallel microchannels is studied numerically by solving the equations governing conservation of mass, momentum and energy in the liquid and vapor phases. The liquid-vapor interface is tracked by a level set method which is modified to include the effects of phase change at the interface and contact angle at the wall. Also, the reversible flow observed during flow boiling in parallel microchannels has been investigated. Based on the numerical results, the effects of contact angle, wall superheat and the number of channels on the bubble growth and reversible flow are quantified.
Reduced Chemical Kinetic Mechanism for Premixed CO/H
Jang, Kyoung ; Cha, Dong-Jin ; Joo, Yong-Jin ; Lee, Ki-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 133~140
DOI : 10.3795/KSME-B.2008.32.2.133
A reduced chemical kinetic mechanism is developed in order to predict the flame phenomena in premixed
flames at atmospheric pressure, aimed at studying the coal gas combustion for the IGCC applications. The reduced mechanism is systematically derived from a full chemical kinetic mechanism involving 11 reacting species and 66 elementary reactions. This mechanism consists of four global steps, and is capable of explicitly calculating the concentration of 7 non-steady species and implicitly predicting the concentration of 3 steady state species. The fuel blend contains two fuels with distinct thermochemical properties, whose contribution to the radical pool in the flame is different. The flame speeds predicted by the reduced mechanism are in good agreement with those by the full mechanism and experimental results. In addition, the concentration profiles of species and temperature are also in good agreement with those by the full mechanism.
Effects of Design Parameters on the Thermal Performance of a Brushless DC Motor
Kim, Min-Soo ; Lee, Kwan-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 141~148
DOI : 10.3795/KSME-B.2008.32.2.141
A numerical simulation of brushless DC motor is performed to elucidate thermo-flow characteristics in winding and bearing with heat generation. Rotation of rotor and blades drives influx of ambient air into the rotor inlet. Recirculation zone exists in the tiny interfaces between windings. The flow separation causes poor cooling performance in bearing part and therefore the redesign of the bearing groove is required. The design parameters such as the inlet location, geometry and bearing groove threshold angle have been selected in the present simulation. As the inlet location moves inward in the radial direction, total incoming flow rate and heat transfer rate are increased. Total incoming flow rate is increased with increasing the inlet inner length. The effect of the bearing groove threshold angle on the thermal performance is less than that of other design parameters.
Effect of Contact Conductance and Semitransparent Radiation on Heat Transfer During CVD Process of Semiconductor Wafer
Yoon, Yong-Seok ; Hong, Hye-Jung ; Song, Myung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 149~157
DOI : 10.3795/KSME-B.2008.32.2.149
During CVD process of semiconductor wafer fabrication, maintaining the uniformity of temperature distribution at wafer top surface is one of the key factors affecting the quality of final products. Effect of contact conductance between wafer and hot plate on predicted temperature of wafer was investigated. The validity of opaque wafer assumption was also examined by comparing the predicted results with Discrete Ordinate solutions accounting for semitransparent radiative characteristics of silicon. As the contact conductance increases predicted wafer temperature increases and the differences between maximum and minimum temperatures within wafer and between wafer and hot plate top surface temperatures decrease. The opaque assumption always overpredicted the wafer temperature compared to semitransparent calculation. The influences of surrounding reactor inner wall temperature and hot plate configuration are then discussed.
Experimental Study on the Secondary Flow Characteristics of a Supercritical Carbon Dioxide Flow in a Gas Cooling Process Within a Square Duct
Han, Seong-Ho ; Seo, Jung-Sik ; Kim, Young-Chan ; Kim, Min-Soo ; Choi, Young-Don ;
Transactions of the Korean Society of Mechanical Engineers B, volume 32, issue 2, 2008, Pages 158~165
DOI : 10.3795/KSME-B.2008.32.2.158
The carbon dioxide properties change sharply near the critical or pseudo-critical point in the heat transfer processes. The reduction in turbulent, convective heat transfer parameters observed in some supercritical data and in experiments with common gases can be due to property variation, acceleration, buoyancy or combinations of these phenomena, depending on the conditions of the applications. In this study, the measurement for the secondary flow driven by buoyancy was carried out on the supercritical carbon dioxide turbulent flows in the different boundary condition with the constant mass flow rate. The available measuring techniques were used to clarify the behaviour of any supercritical fluid. Laser Doppler Velocimeter (LDV) and a special device was used to measure the secondary velocity and turbulent characteristics of the supercritical flows.