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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 20, Issue 12 - Dec 1996
Volume 20, Issue 11 - Nov 1996
Volume 20, Issue 10 - Oct 1996
Volume 20, Issue 9 - Sep 1996
Volume 20, Issue 8 - Aug 1996
Volume 20, Issue 7 - Jul 1996
Volume 20, Issue 6 - Jun 1996
Volume 20, Issue 5 - May 1996
Volume 20, Issue 4 - Apr 1996
Volume 20, Issue 3 - Mar 1996
Volume 20, Issue 2 - Feb 1996
Volume 20, Issue 1 - Jan 1996
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Nitric Oxide and Carbon Monoxide Emission from a Premixed Flame Stabilized in a Porous Ceramic Matrix Burner
Jeong, Jong-Su ; Lee, Gyo-U ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3243~3250
DOI : 10.22634/KSME-B.1922.214.171.12443
Emission characteristics of nitric oxides and carbon monoxide from a porous media combustor has been experiment studied. The relationship between the change of flame shape and emission has also been examined. As the equivalence ratio decreases, the flame shape on the ceramic matrix plate changes from a diffusion flame, R(radiant)-type flame, to B(Blue)-type flame. With large fuel flow rate, R-type flame turns to be two dimensional R-II type flame around the equivalence of 0.7. Carbon monoxide emission increases very rapid with decreasing equivalence ratio. It changes a lot from some 10 ppm to 100-10,000 ppm with the change of flame type from R-I to R-II type. Nitric oxide emission from the premixed burner is less than 25 ppm over all range of fuel flow rate, which is less than 20% of NOx emission from conventional gas burners.
Experimental Study on Flows within an Unshrouded Centrifugal Impeller Passage(II)-on the Influence of Flow Rate-
Kim, Seong-Won ; Jo, Gang-Rae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3251~3261
DOI : 10.22634/KSME-B.19126.96.36.19951
Flows were measured in an unshrouded centrifugal impeller. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes between the inlet and outlet of the impeller rotating at 700 rpm, which diameter is 0.39 meter, and the static pressures and the slip factor at the impeller outlet were estimated from the measured values. Measurements were made for three flow rates corresponding to zero incidence and two others with the greater and the smaller one than zero. From the measured data in these flow rates, the followings were investigated in the impeller passage, the variation of the primary and secondary flows, the leakage flows, the wake's position and its size, the static pressure rise and the loss production mechanism. Furthermore the static pressure and the slip factor were compared with the results of inviscid Quasi-3D calculation.
Experimental Study on Flows within a Shrouded Centrifugal Impeller Passage -at the Shockless Condition-
Kim, Seong-Won ; Jo, Gang-Rae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3262~3271
DOI : 10.22634/KSME-B.19188.8.131.5262
Flow patterns were measured in a shrouded centrifugal impeller. The flow rate in measurements was fixed at the value corresponding to a nearly zero incidence at the blade inlet. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes from the inlet to the outlet of impeller rotating at 700 rpm, and the static pressure distribution along flow passage and the slip factor at impeller outlet were calculated from the measured values. From these measured data, the primary and secondary flows, the wake production and the static pressure rise in the impeller passage were investigated. Furthermore, the secondary flow patterns and the wake's location in this impeller passage were compared with those of the unshrouded impeller.
Numerical study on flows within an shrouded centrifugal impeller passage
Kim, Seong-Won ; Jo, Gang-Rae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3272~3281
DOI : 10.22634/KSME-B.19184.108.40.20672
The flow analysis method which had been developed for the numerical calculation of 3-dimensional, incompressible and turbulent flow within an axial compressor was extended to the flow field within centrifugal impeller. In this method based on the SIMPLE(Semi Implicit Method Pressure Linked Equations) algorithm, the coordinate transformation was adopted and the standard k-.epsilon. model using wall function was used for turbulent flow analysis. The calculated flow fields have agreed very well with measurement results. Especially, 3-dimensional and viscous flow characteristics including secondary flows, jet-wake flow and decreased pressure rise along impeller passage, which can't be predicted by inviscid Q3D calculation were predicted very reasonably.
A study on the influence of turbulence characteristics on flame propagation in swirl flow field
Lee, Sang-Jun ; Lee, Jong-Tae ; Lee, Seong-Yeol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3282~3292
DOI : 10.22634/KSME-B.19220.127.116.1182
Flow velocity was measured using a hot wire anemometer. Turbulence intensity was in proportion to mean flow velocity regardless of swirl velocity. And integral length scale has proportional relation with swirl velocity regardless of measurement position. Flame speed calculated by radius of visualized flame was increased and then decreased according to lapse of time from spark. Maximum flame speed was increased according to increase of turbulence intensity. Burning speed and flame transport effect increased with increase of swirl velocity, but ratio of burning speed to flame speed decreased with increased of swirl velocity. Mass fraction burned versus volume fraction burned was increased in proportion to the increase of turbulence intensity, caused by increase of combustion promotion effect according to increase of turbulence intensity and scale.
Analysis of heat and mass transfer in a vertical tube absorber cooled by air
Kim, Seon-Chang ; O, Myeong-Do ; Lee, Jae-Heon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3293~3303
DOI : 10.22634/KSME-B.1918.104.22.16893
Numerical analyses have been performed to estimate the absorption heat and mass transfer coefficients in absorption process of the LiBr aqueous solution and the total heat and mass transfer rates in a vertical tube absorber which is coolING ed by air. Axisymmetric cylindrical coordinate system was adopted to model the circular tube and the transport equations were solved by the finite volume method. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by water vapor in tube. Effects of film Reynolds number on heat and mass transfer coefficients have been also investigated. Especially, effects of tube diameter have been considered to observe the total heat and mass transfer rates through falling film along the tube. Based on the analysis it has been found that the total mass transfer rate increases rapidly in a region with low film Reynolds number(10 ~ 40) as the film Reynolds number increases, while decreases beyond that region. The total heat and mass transfer rates increase with increasing the tube diameter.
Convective heat transfer characteristics of a two-dimensional turbulent wall attaching offset jet
Yun, Sun-Hyeon ; Lee, Dae-Hui ; Song, Heung-Bok ; Kim, Dae-Seong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3304~3312
DOI : 10.22634/KSME-B.1922.214.171.12404
An experimental study on the convective heat transfer characteristics was performed for a two-dimensional wall attaching offset jet(WAOJ). Thermochromic liquid crystal was used to measure the plate wall temperature. The Nusselt number was measured for Reynolds numbers from 6, 500 to 39, 000, and the offset ratios from 0.5 to 15. The maximum Nusselt number point coincides with the time-averaged reattachment point and Nusselt number decreases monotonically after the jet reattaches on the wall. In the recirculation region Nusselt number minimize near the upstream corner and then increases as X/D decreases to vanishes. This suggests the existence of secondary vortices, causing an additional mixing of the flow in the corner. The correlations between the local Nusselt number and Reynolds number, Re, offset ratio, H/D, and streamwise distance, X/D are presented.
Effect of supercooling on the cooling in horizontal cylindrical annuli
Yun, Jeong-In ; Kim, Jae-Dol ; Kato, Toyofumi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3313~3321
DOI : 10.22634/KSME-B.19126.96.36.19913
A fundamental study in cooling and solidification process focused on ice storage was performed, including the interesting phenomena of density inversion, supercooling and dendritic ice. A numerical study was performed for natural convection and ice formation in the cooling and freezing processes with supercooling in a space between double cylinders. When water was cooled under the freezing point by a cooling wall in a cavity, solidification was not started at once, but a subcooled region was formed near the wall. Especially, when the cooling rate was low, subcooled region extended to a wide area. However, after a few minutes, supercooling is released by some triggers. Dendritic ice is suddenly formed within a subcooled region, and a dense ice layer begins to be developed from the cooling wall. Due to the difficulties, most previous studies on solidification process with numerical methods had not treated the supercooling phenomena, i.e. the case considering only the growth of dense ice. In this study, natural convection and ice formation considering existence of supercooling and dendritic ice were analyzed numerically with using finite difference method and boundary fixing method. The results of numerical analysis were well compared with the experimental results.
Effects of the crystal rotation on heat transfer and fluid flow in the modified floating-zone crystal growth
Seo, Jeong-Se ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3322~3333
DOI : 10.22634/KSME-B.19188.8.131.5222
A numerical analysis has been conducted to investigate a modified floating-zone crystal growth process in which most of the melt surface is covered with a heated ring. The crystal rod is not only pulled downward but rotated around its axisymmetric line during crystal growth process in order to produce the flat interface of crystal growth and the single crystal growth of NaNO3 is considered in 6mm diameter. The present study is made from a full-equation-based analysis considering a pulling velocity in all of solid and liquid domains and both of solid-liquid interfaces are tracked simultaneously with a governing equation in each domain. Numerical results are mainly presented for the comparison of the surface shape of rotational crystal rod with that of no-rotational crystal rod and the effects of revolution speeds of the crystal rod. Results show that the rotation of crystal rod produces more its flat surface. In addition, the shape of crystal growth near the centerline is more concaved with the increase in the revolution speed of crystal rod. The flow pattern and temperature distribution is analyzed and presented in each case. As the pulling velocity of crystal rod is increasing, the free surface of the melt below the heated ring is enlarged due to the crystal interface migrating downward.
Simultaneous velocity and temperature measurement of thermo-fluid flows by using particle imaging technique
Lee, Sang-Jun ; Baek, Seung-Jo ; Yun, Jeong-Hwan ; Do, Deok-Hui ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3334~3343
DOI : 10.22634/KSME-B.19184.108.40.20634
A quantitative flow visualization technique was developed to measure velocity and temperature fields simultaneously in a two-dimensional cross section of thermo-fluid flows. Thermochromic liquid crystal(TLC) particles are used as temperature sensor and velocity tracers. Illuminating a thermo-fluid flow with a thin sheet of white light, the reflected colors from the TLC particles in the flow were captured simultaneously by two CCD cameras; a 3-chip CCD color camera for temperature field measurement and a black and white CCD camera for velocity field measurement. Variations of temperature field were measured by using a HSI true color image processing system and TLC solution. The relationship between the hue values of TLC color image and real temperature was obtained and this calibration curve was used to measure the true temperature under the same camera and illumination condition. The velocity field was obtained by using a 2-frame PTV technique using the concept of match-probability to track true velocity vectors from two consecutive image frames. These two techniques were applied at the same time to the unsteady thermal-fluid flow in a Hele-Shaw cell to measure the temperature and velocity field simultaneously and some results are discussed.
An experimental and numerical study on natural convection-radiation conjugate heat transfer in a three-dimensional enclosure having a protruding heat source
Baek, Chang-In ; Lee, Gwan-Su ; Kim, Woo-Seung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3344~3354
DOI : 10.22634/KSME-B.19220.127.116.1144
An experimental and numerical study on the three-dimensional natural convection-radiation conjugate heat transfer in the enclosure with heat generating chip has been performed. A 3-dimensional simulation model is developed by considering heat transfer phenomena by conduction-convection and radiation. Radiative transfer was analyzed with the discrete ordinates method. Experiments are conducted in order to validate the numerical model. Comparisons with the experimental data show that good agreement is obtained when the radiation effect is considered. The effects of the thermal conductivity of the substrate and power level on heat transfer are investigated. It is shown that radiation is the dominant heat transfer mode and the conductivity of the substrate has important effects on the heat transfer in the enclosure.
The study on the combustion characteristics of a planar flame burner as a calibration source of laser diagnostics
Gil,Yong-Seok ; Jeong, Seok-Ho ; Lee, Byeong-Jun ; Han, Jae-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3355~3360
DOI : 10.22634/KSME-B.1918.104.22.16855
To provide standard data of temperature and species concentration in a flame for calibrating the laser based combustion diagnostics, we investigated combustion characteristics of a flat flame burner(Mckennar Product). For various stoichiometric ratios we measured temperature and concentration of OH in the premixed methane/air flame with Coherent anti-Stokes Raman spectroscopy and laser induced fluorescence technique, respectively. Assuming the chemical equilibrium condition at the measured temperature, the mole fraction of the OH radical in the flame was obtained and compared with numerical analysis.
Analysis on the non-equilibrium dendritic solidification of a binary alloy with back diffusion
Jeong, Jae-Dong ; Yu, Ho-Seon ; Lee, Jun-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3361~3370
DOI : 10.22634/KSME-B.1922.214.171.12461
Micro-Macro approach is conducted for the mixture solidification to handle the closely linked phenomena of microscopic solute redistribution and macroscopic solidification behavior. For this purpose, present work combines the efficiency of mixture theory for macro part and the capability of microscopic analysis of two-phase model for micro part. The micro part of present study is verified by comparison with experiment of Al-4.9 mass% Cu alloy. The effect of back diffusion on the macroscopic variables such as temperature and liquid concentration, is appreciable. The effect, however, is considerable on the mixture concentration and eutectic fraction which are indices of macro and micro segregation, respectively. According to the diffusion time, the behavior near the cooling wall where relatively rapid solidification permits short solutal diffusion time, approaches Scheil equation limit and inner part approaches lever rule limit.
A study on the wsggm-based spectral modeling of radiation properties of water vapor
Kim, Uk-Jung ; Song, Tae-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3371~3380
DOI : 10.22634/KSME-B.19126.96.36.19971
Low resolution spectral modeling of water vapor is carried out by applying the weighted-sum-of-gray-gases model (WSGGM) to a narrow band. For a given narrow band, focus is placed on proper modeling of gray gas absorption coefficients vs. temeprature relation used for any solution methods for the Radiative Transfer Equation(RTE). Comparison between the modeled emissivity and the "true" emissivity obtained from a high temperatue statistical narrow band parameters is made ofr the total spectrum as well as for a few typical narrow bands. Application of the model to nonuniform gas layers is also made. Low resolution spectral intensities at the boundary are obtained for uniform, parabolic and boundary layer type temeprature profiles using the obtained for uniform, parabolic and boundary layer type temperature profiles using the obtained WSGGM's with 9 gray gases. The results are compared with the narrow band spectral intensities as obtained by a narrow band model-based code with the Curtis-Godson approximation. Good agreement is found between them. Local heat source strength and total wall heat flux are also compared for the cases of Kim et al, which again gives promising agreement.
Effect of methanol-blended fuel properties on the combustion characteristics of a gasoline engine
Jo, Haeng-Muk ; Lee, Chang-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 10, 1996, Pages 3381~3386
DOI : 10.22634/KSME-B.19188.8.131.5281
The engine performance and combustion characteristics of methanol blended fuel in spark ignition engine were discussed on the basis of experimental investigation. The effects of methanol blending fuel on combustion in cylinder were investigated under various conditions of engine cycle and blending ratio. The results showed that the engine performance was influenced by the methanol blending ratio and the variations of operating conditions of test engine. The increase of fuel temperature brought on the improvement of combustion characteristics such as cylinder pressure, the rate of pressure rise and heat release in an engine. The burning rate of fuel-air mixture, the exhaust emissions and the other characteristics of performance were discussed also.