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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
Selecting the target year
Some Relations Between the Geometric Parameters and Internal Flow Field Characteristics in Multiblade Fan/Scroll System
Maeng, Joo-Sung ; Yoo, Dal-Hyun ; Lee, Kwang-Ho ; Park, ln-Gyu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1139~1147
DOI : 10.22634/KSME-B.2000.24.9.1139
This paper describes that the size of inactive zone can be directly applied to design multiblade fan/scroll system. From the experimental studies using a five hole pitot tube and smoke test, it is found that the size of inactive zone has linear relations with the mean velocity of impeller inlet and cut-off angle gives a great influences to the fan efficiency. For the practical design, a function related with geometric parameters(i.e. inner radius, cord length, cut-off clearance and cut-off angle) of fan/scroll system is suggested. By using these formulas, the size and distribution of inactive zone can be predicted without the measurements through the full domain, it can be possible to use them to know the efficiency improvement for new model designed.
Modification of QUICK Scheme for Unstructured Grid Finite Volume Method
Kang, Dong Jin ; Bae, Sang Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1148~1156
DOI : 10.22634/KSME-B.2000.24.9.1148
The QUICK scheme for convection terms is modified for unstructured finite volume method by using linear reconstruction technique and validated through the computation of two well defined laminar flows. It uses two upstream grid points and one downstream grid point in approximating the convection terms. The most upstream grid point is generated by considering both the direction of flow and local grid line. Its value is calculated from surrounding grid points by using a linear construction method. Numerical error by the modified QUICK scheme is shown to decrease about 2.5 times faster than first order upwind scheme as grid size decreases. Computations are also carried out to see effects of the skewness and irregularity of grid on numerical solution. All numerical solutions show that the modified QUICK scheme is insensitive to both the skewness and irregularity of grid in terms of the accuracy of solution.
A Study on the Characteristic of Beakdown Voltage for Combustion Diagnostic of Gasoline Engine
Park, Jae-Keun ; Jo, Min-Seok ; Whang, Jae-Won ; Jang, Gi-Hyun ; Chae, Jae-Ou ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1157~1165
DOI : 10.22634/KSME-B.2000.24.9.1157
A classic examples of the abnormal combustions are the knock and misfire, which raise noxious performance and life of the engine. A heavy knock can also cause severe damages to the engine itself, which gives more reason why it must be detected and corrected. With the response of the today's requirements, we have researched the new diagnostic system which uses the breakdown voltage characteristics between electrodes of spark plug. This breakdown voltage depends on the pressure, temperature and even the shape and material of electrodes. But there is no data of breakdown voltage in case of using the spark plug as a electrodes. So, in this study, we show the breakdown voltage characteristic by pressure and temperature in constant volume bomb, which will make it possible to diagnose the engine combustion phenomenon.
Numerical Study on the Two-Dimensional Heat Flow in High-Power Density Welding Process
Park, Kun-Joong ; Jang, Kyung-Chun ; Kim, Charn-Jung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1166~1174
DOI : 10.22634/KSME-B.2000.24.9.1166
This work presents a two-dimensional quasi-steady state model to study the fluid flow and heat transfer in high-power density welding process of thin AISI-304 stainless steel plates. The enthalpy method and the finite volume method were used for a numerical analysis of the mushy region phase change as well as the heat flow at the weld pool and the heat-affected zone. The results show that the mushy region distributed around the weld pool becomes wider downstream and the surface heat losses by convection and radiation can be significant factors in welding process especially when a welding speed is relatively low.
Shelter Effect of Porous Fences on the Saltation of Sand Particles in an Atmospheric Boundary Layer
Park, Ki-Chul ; Lee, Sang-Joon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1175~1184
DOI : 10.22634/KSME-B.2000.24.9.1175
Effects of porous wind fences on the wind erosion of particles from a triangular sand pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Flow visualization was carried out to investigate the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the particle size, fence porosity
and the height of sand pile. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity
=30% was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles. With increasing the sand particle diamter, the threshold velocity was also increased. When the height of sand pile is lower than the fence height, threshold velocity is enhanced.
A Study on the Characteristics of Intake Port Flow and Performance with Swirl Ratio Variance in a Turbocharged D.I. Diesel Engine
Yoon, Jun-Kyu ; Cha, Kyung-Ok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1185~1194
DOI : 10.22634/KSME-B.2000.24.9.1185
The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.
The Study on the Development of The Non-Gravity Fluidized Dryer
Kim, Seok-Cheol ; Bae, Dong-Kyu ; Han, Ji-Woong ; Kum, Sung-Min ; Lee, Chang-Eon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1195~1209
DOI : 10.22634/KSME-B.2000.24.9.1195
The purpose of this study is to develop the non-gravity fluidized dryer. In this non-gravity fluidized dryer the fluidized zone is produced by two paddles in mixer, which maximizes the surface area of materials and then heated air through the guiding panels dehumidify them. This can conduct the drying process quickly and control moisture contents to lower limits. The ventilation system is closed loop system, which can be changeable to open system, and can be used as a multi-purposed dryer in which mixing, drying, granulating and cooling process is conducted. In order to develop the non-gravity fluidized dryer, in the first fundamental experiments were performed to mixing accuracy and then the other parts of dryer and control system were examined to check whether they were designed properly and operated harmoniously with mixer. Also the preparatory experiments were fulfilled to examine the efficiency and reliability of the dryer. Lastly, on the basis of preparatory experiments, performance test for the non-gravity fluidized dryer carried out for the variation of the initial moisture contents, desired moisture contents, heated air velocity and heating temperature.
Bifurcation to Chaotic Thermal Convection in a Horizontal Annulus
Yoo, Joo-Sik ; Kim, Yong-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1210~1218
DOI : 10.22634/KSME-B.2000.24.9.1210
Thermal convection in a horizontal annulus is considered, and the bifurcation phenomena of flows from time-periodic to chaotic convection are numerically investigated. The unsteady two-dimensional streamfunction-vorticity equation is solved with finite difference method. As Rayleigh number is increased, the steady flow bifurcates to a time-periodic flow with a fundamental frequency, and afterwards a period-tripling bifurcation occurs with further increase of the Rayleigh number. Chaotic convection is established after a period-doubling bifurcation. A periodic convection with period 4 appears after the first chaotic convection. At still higher Rayleigh numbers, chaotic flows reappear.
An Efficient Method for Mold Thermal Cycle Analysis in Repeated Forming Process of TV Glass
Choi, Joo-Ho ; Kim, Jun-Bum ; Hwang, Jung-Hea ; Ha, Duk-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1219~1226
DOI : 10.22634/KSME-B.2000.24.9.1219
An efficient method is developed for plunger thermal cycle analysis in repeated forming process of the TV glass. The plunger undergoes temperature fluctuation during a cycle due to the repeated contact and separation from the glass, which attains a cyclic steady state having same temperature history at every cycle. Straightforward analysis of this problem brings about more than 80 cycles to get reasonable solution, and yet hard to setup stopping criteria due to extremely slow convergence. An exponential fitting method is proposed to overcome the difficulty, which finds exponential function to best approximate temperature values of 3 consecutive cycles, and new cycle is restarted with the fitted value at infinite time. Numerical implementation shows that it reduces the number of cycles dramatically to only 6-18 cycles to reach convergence within 10 accuracy. A system for the analysis is constructed, in which the thermal analysis is performed by commercial software ANSYS, and the fitting of the result is done by IMSL library. From the parametric studies, one reveals some important facts that although the plunger cooling or the glass thickness is increased, its counter part in contact is not much affected, duo to the low thermal conductance of the glass.
Effects of Spatial Discretization Schemes on Numerical Solutions of Viscoelastic Fluid Flows
Min, Tae-Gee ; Yoo, Jung-Yul ; Choi, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1227~1238
DOI : 10.22634/KSME-B.2000.24.9.1227
This study examines the effects of the discretization schemes on numerical solutions of viscoelastic fluid flows. For this purpose, a temporally evolving mixing layer, a two-dimensional vortex pair interacting with a wall, and a turbulent channel flow are selected as the test cases. We adopt a fourth-order compact scheme (COM4) for polymeric stress derivatives in the momentum equations. For convective derivatives in the constitutive equations, the first-order upwind difference scheme (UD) and artificial diffusion scheme (AD), which are commonly used in the literature, show most stable and smooth solutions even for highly extensional flows. However, the stress fields are smeared too much and the flow fields are quite different from those obtained by higher-order upwind difference schemes for the same flow parameters. Among higher-order upwind difference schemes, a third-order compact upwind difference scheme (CUD3) shows most stable and accurate solutions. Therefore, a combination of CUD3 for the convective derivatives in the constitutive equations and COM4 for the polymeric stress derivatives in the momentum equations is recommended to be used for numerical simulation of highly extensional flows.
Wall Heat Flux Behavior of Nucleate Pool Boiling Under a Constant Temperature Condition in a Binary Mixture System
Bae, Sung-Won ; Lee, Han-Choon ; Kim, Moo-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1239~1246
DOI : 10.22634/KSME-B.2000.24.9.1239
The objective of this work is to measure space and time resolved wall heat fluxes during nucleate pool boiling of R113/R11 mixtures using a microscale heater array in conjunction with a high speed CCD. The microscale heater array is constructed using VLSI techniques, and consists of 96 serpentine platinum resistance heaters on a transparent quartz substrate. Electronic feedback circuits are used to keep the temperature of each heater at a specified temperature and the variation in heating power required to keep the temperature constant is measured. Heat flux data around an isolated bubble are obtained with triggered CCD images. CCD images are obtained at a rate of 1000frames/second. The heat transfer variation vs. time on the heaters directly around the nucleation site is plotted and correlated with images of the bubble obtainedby using the high speed CCD. For both of the mixture(R11/R113) and pure system(pure R11, pure R113), the wall heat fluxes are presented and compared to find out the qualitative difference between pure and binary mixture nucleate boiling.
A Study on the Effect of Recirculated Exhaust Gas with Scrubber EGR System upon Exhaust Emissions in Diesel Engines
Bae, Myung-Whan ; Ha, Jung-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1247~1254
DOI : 10.22634/KSME-B.2000.24.9.1247
The effects of recirculated exhaust gas on the characteristics of
and soot emissions under a wide range of engine load have been experimentally investigated by a water-cooled, four-cylinder, indirect injection, four cycle and marine diesel engine operating at two kinds of engine speeds. The simultaneous control of
and soot emissions in diesel engines is targeted in this study. The EGR system is used to reduce
emissions, and a novel diesel soot removal device with a cylinder-type scrubber for the experiment system which has 6 water injectors(A water injector has 144 nozzles in 1.0 mm diameter) is specially designed and manufactured to reduce the soot contents in the recirculated exhaust gas to intake system of the engines. The intake oxygen concentration and the mean equivalence ratio calculated by the intake air flow and fuel consumption rate, and the exhaust oxygen concentration measured are used to analyse and discuss the influences of EGR rate on
and soot emissions. The experiments are performed at the fixed fuel injection timing of
BTDC regardless of experimental conditions. It is found that
emissions are decreased and soot emissions are increased owing to the drop of intake oxygen concentration and exhaust oxygen concentration, and the rise of equivalence ratio as the EGR rate rises.
Modification of Turbulent Boundary Layer Flow by Local Wall Vibration
Kim, Chul-Kyu ; Jeon, Woo-Pyung ; Park, Jin-Il ; Kim, Dong-Joo ; Choi, Haecheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1255~1263
DOI : 10.22634/KSME-B.2000.24.9.1255
In this study, the modification of turbulent boundary layer flow by local wall vibration is investigated. The wall is locally vibrated using a wall deformation actuator, which moves up and down at the frequencies of 100Hz and 50Hz. Simultaneous measurements of the streamwise velocities in the spanwise direction are performed at several wall-normal and streamwise locations using an in-house multi-channel hot wire anemometer and a spanwise hot-wire-probe rake. The mean velocity is reduced in most places due to the wall vibration and its reduced amount becomes small as flow goes downstream. Interestingly, the mean velocity is found to increase very near the wall and near the actuator. This is due to the motion induced by the streamwise vortices which are generated by the downward motion of the actuator. In case of the streamwise velocity fluctuations, their magnitude increases as compared to the unperturbed turbulent boundary layer, and the increased amount becomes small as the flow moves downstream. The modified flow field at the forcing frequency of 50Hz is not much different from that of 100Hz, except the reduced amount of modification.
Numerical Design of Light-off Auto-Catalyst for Reducing Cold-Start Emissions
Jeong, Soo-Jin ; Kim, Woo-Seung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1264~1276
DOI : 10.22634/KSME-B.2000.24.9.1264
Light-off catalyst has been used for minimization of cold-start emissions. Improved cold-start performance of light-off catalyst needs the optimal design in terms of flow distribution, geometric surface area, precious metal loading, cell density and space velocity. In this study, these influential factors are numerically investigated using integrated numerical technique by considering not only 3-D fluid flow but also heat and mass transfer with chemical reactions. The present results indicate that uneven catalyst loading of depositing high active catalyst at upstream of monolith is beneficial during warm-up period but its effect is severely deteriorated when the space velocity is above 100,000
To maximize light-off performance, this study suggests that 1) a light-off catalyst be designed double substrate type; 2) the substrate with high GSA and high PM loading at face be placed at the front monolith; and 3) the cell density of the rear monolith be lower to reduce the pressure drop.
Enhancement of Convective Heat Transfer by Using a Micro-Encapsulated Phase-Change-Material Slurry
Jung, Dong-Ju ; Choi, Eun-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 24, issue 9, 2000, Pages 1277~1284
DOI : 10.22634/KSME-B.2000.24.9.1277
To enhance heat transfer characteristics of water, micro-encapsulated octadecane of about
diameter was added to water. Viscosity of the slurry was measured by using a capillary tube viscometer. The measured viscosity decreased as the temperature of the slurry increased, and it increased as the fraction of the capsules in the slurry increased. Thermal characteristics of the octadecane were studied by using a differential scanning calorimeter. The melting temperature and the melting energy of the octadecane were found to be
and 34.4kcal/kg, respectively. The convective heat transfer characteristics of the slurry were investigated in a flow loop with a constant heat flux test section. Friction factor of the slurry flow was found to be similar to the expected curve by Petukhov. The Nusselt number of the slurry flow was highest when the octadecane melted. Effective thermal capacity of the 14.2% slurry was found to have 1.67 times of the thermal capacity of water.