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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
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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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Numerical simulation of turbulent flows through linear turbine cascades with high turning angles
Lee, Hun-Gu ; Yu, Jeong-Yeol ; Yun, Jun-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3917~3925
DOI : 10.22634/KSME-B.19220.127.116.1117
A numerical analysis on three dimensional turbulent incompressible flows through linear cascades of turbine rotor blades with high turning angles has been performed by using a generalized k-.epsilon. model which is a high Reynolds number form and derived by RNG(renormalized group) method to account for the variation of the rate of strain. A second order upwind scheme is used to suppress numerical diffusion in approximating the convective terms. Body-fitted coordinates are adopted to represent the complex blade geometry accurately. For the case without tip clearance, velocity vectors and static pressure contours are shown to be in good agreement with previous experimental results. For the case with tip clearance, the effects of the passage vortex and tip clearance flow on the total pressure loss as well as their interactions are discussed.
Reassessment on numerical results by the continuum model
Jeong, Jae-Dong ; Yu, Ho-Seon ; No, Seung-Tak ; Lee, Jun-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3926~3937
DOI : 10.22634/KSME-B.1918.104.22.16826
In recent years there has been increased interest in the continuum model associated with the solidification of binary mixtures. A review of the literature, however, shows that the model verification was not sufficient or only qualitative. Present work is conducted for the reassessment of continuum model on the solidification problems of binary mixtures widely used for model validation. In spite of using the same continuum model, the results do not agree well with those of Incropera and co-workers which are benchmark problems typically used for validation of binary mixture solidification. Inferring from the agreement of present results with the analytic, experimental and other model's numerical results, this discrepancy seems to be caused by numerical errors in applying continuum model developed by Incropera and co-workers, not by the model itself. Careful examination should be preceded before selecting validation problems.
Heat transfer characteristics of fin and tube heat exchangers with various interrupted surface for air conditioning application
Yun, Jeom-Yeol ; Lee, Gwan-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3938~3948
DOI : 10.22634/KSME-B.1922.214.171.12438
This study is related with the experimental investigation on the heat transfer and pressure drop characteristics of the fin-and-tube heat exchangers with three different interrupted fins and a plane fin for air-conditioning application. Experiments were conducted accordingly following the appropriate development process. Geometry similitude experiment was introduced to predict the performance of fins, and prototype experiment was also performed to confirm the validity of geometry similitude experimental results. However, these experimental results were limited to the sensible heat transfer characteristics of the heat exchangers. Hence, additional experiment was performed using refrigerant to investigate the latent heat transfer characteristics. This paper presents an appropriate process for the development of a new type heat exchanger. Sensible and latent heat transfer characteristics for each fin configuration is also provided along with the optimal fin configuration.
A study of a new interfacial instability between two vertical fluid layers of different densities
Lee, Cheol-U ; Ju, Sang-U ; Lee, Sang-Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3949~3959
DOI : 10.22634/KSME-B.19126.96.36.19949
A new interfacial instability between two vertical fluid layers of different densities is studied. The two layers are flowing between two parallel vertical plates vertically upward or downward, forming counter- or concurrent flows. In order to extend the study to highly-nonlinear regime in future studies, a nonlinear interface evolution equation is derived, and the stability analysis is performed based on the evolution equation. Among the parameters studies are the ratios of the fluid densities and layer thicknesses and the net flow rate.
Fluid Flow in a Circular Cylinder Subject to Circulatory Oscillation-Theoretical Analysis
Seo,Yong-Gwon ; Kim, Hyeon-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3960~3969
DOI : 10.22634/KSME-B.19188.8.131.5260
A fluid flow inside a circular cylinder subject to horizontal and circular oscillation is analyzed theoretically. Under the assumption of small-amplitude oscillation, the governing equations take linear forms. The velocity field is obtained in terms of the first kind of Bessel function of order 1. It was found that a particle describes an orbit close to a circle in the central region and an arc near the side wall. We also obtained the Stokes' drift velocity induced by the traveling wave along the circumferential direction. The Eulerian streaming velocities at the edge of the bottom and side boundary layers were also obtained. It was shown that the vertical component of the steady streaming velocity on the side wall is almost proportional to the amplitude of the free surface motion.
Fluid Flow in a Circular Cylinder Subject to Circulatory Oscillation-Numerical Analysis and Experiment
Seo,Yong-Gwon ; Park, Jun-Gwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3970~3979
DOI : 10.22634/KSME-B.19184.108.40.20670
A fluid flow inside a circular cylinder subject to horizontal, circular oscillation is analyzed numerically and experimentally. The steady streaming velocities at the edges of the boundary layers on the bottom and side surfaces of the cylinder obtained in the previous paper are used as the boundary conditions in the governing equations for the steady flow motion in the interior region. The Stokes' drift velocity obtained in the previous paper also constitutes the Lagrangian velocity which is used in the momentum equations. It turns out that the interior steady flow is composed of one cell, ascending at the center and descending near the side surface, at the streaming Reynolds number 2500. However, at the streaming Reynolds number 25, the flow field is divided into two cells resulting in a descending flow at the center. The experimentally visualized flow patterns at the bottom surface agree well with the analytical solutions. The visualization experiment also confirms the flow direction as well as the center position of the cell obtained by the numerical solutions.
Passive control of condensation shock wave in supersonic nozzles
Kim, Hui-Dong ; Gwon, Sun-Beom ; Setoguchi, Toshiaki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3980~3990
DOI : 10.22634/KSME-B.19220.127.116.1180
When a moist air is rapidly expanded in a supersonic nozzle, nonequilibrium condensation occurs at a supersaturation state. Condensation shock wave appears in the nozzle flow if the releasing latent heat due to condensation goes beyond a critical value. It has been known that self-excited oscillations of the condensation shock wave generate in an air or a steam nozzle flow with a large humidity. In the present study, the passive control technique using porous wall with a cavity underneath was applied to the condensation shock wave. The effects of the passive control on the steady and self-excited condensation shock waves were experimentally investigated by Schlieren visualization and static pressure measurements. The result shows that the present passive control is a useful technique to suppress the self-excited oscillations of condensation shock wave.
Laminar Convective Heat Transfer of a Bingham Plastic in a Circular Pipe(I) Analytical approach- thermally fully developed flow and thermally develping flow(the Graetz problem extended)
Min, Tae-Gi ; Yu, Jeong-Yeol ; Choe, Hae-Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 3991~4002
DOI : 10.22634/KSME-B.1918.104.22.16891
Thermally fully developed and thermally developing laminar flows of a Bingham plastic in a circular pipe have been studied analytically. For thermally fully developed flow, the Nusselt numbers and temperature profiles are presented in terms of the yield stress and Peclet number, proposing a correlation formula between the Nusselt number and the Peclet number. The solution to the Graetz problem has been obtained by using the method of separation of variables, where the resulting eigenvalue problem is solved approximately by using the method of weighted residuals. The effects of the yield stress, Peclet and Brinkman numbers on the Nusselt number are discussed.
Laminar Convective Heat Transfer of a Bingham Plastic in a Circular Pipe(II) Numerical approach-hydrodynamically develrping flow and simultaneously developing flow
Min, Tae-Gi ; Choe, Hyeong-Gwon ; Choe, Hae-Cheon ; Yu, Jeong-Yeol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4003~4012
DOI : 10.22634/KSME-B.1922.214.171.12403
Hydro dynamically developing and simultaneously (hydro dynamically and thermally) developing laminar flows of a Bingham plastic in a circular pipe have been investigated numerically. Solutions have been obtained by using a four-step fractional method combined with an equal order bilinear finite element method. For the hydro dynamically developing flow, shorter entrance length is required to reach fully developed velocity field for larger yield stress and non-monotonic pressure drop along the pipe centerline is observed when the yield stress exceeds a certain critical value. For the simultaneously developing flow, the heat transfer characteristics show the same trends as those predicted for the thermally developing flow (Graetz problem).
A numerical study of flow and heat transfer characteristics varied by impingement jet in turbine blade cooling
Lee, Jeong-Hui ; Kim, Sin-Il ; Yu, Hong-Seon ; Choe, Yeong-Gi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4013~4026
DOI : 10.22634/KSME-B.19126.96.36.19913
A numerical simulation has been carried out for the jet impinging on a flat plate and a semi-circular concave surface. In this computation finite volume method was employed to solve the full Navier-Stokes equation based on a non-orthogonal coordinate with non staggered variable arrangement. The standard k-.epsilon. turbulent model and low Reynolds number k-.epsilon. model(Launder-Sharmar model) with Yap's correction were adapted. The accuracy of the numerical calculations were compared with various experimental data reported in the literature and showed good predictions of centerline velocity decay, wall pressure distribution and skin friction. For the jet impingement on a semi-circular concave surface, potential core length was calculated for two different nozzle(round edged nozzle and rectangular edged nozzle) to consider effects of the nozzle shape. The result showed that round edged nozzle had longer potential core length than rectangular edged nozzle for the same condition. Heat transfer rate along the concave surface with constant heat flux was calculated for various nozzle exit to surface distance(H/B) in the condition of same jet velocity. The maximum local Nusselt number at the stagnation point occurred at H/B = 8 where the centerline turbulent intensity had maximum value. The predicted Nusselt number showed good agreement with the experimental data at the stagnation point. However heat transfer predictions along the downstream were underestimated. This results suggest that the improved turbulence modeling is required.
Factors influencing on the discharge coefficients of sonic nozzle
Yu, Seong-Yeon ; Lee, Sang-Yun ; Park, Gyeong-Am ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4027~4035
DOI : 10.22634/KSME-B.19188.8.131.5227
Accuracy of gas flow measurements using sonic nozzle and factors which influence on the discharge coefficients of sonic nozzle are investigated with high pressure gas flow standard measurement system. The gas flow measurement system comprises two compressors, storage tank, temperature control loop, sonic nozzle test section, weighing tank, gyroscopic scale and data acquisition system. The experiments are performed at various nozzle throat diameter and inlet pressure. Overall uncertainty of discharge coefficients is estimated to less than .+-.0.2% and most of experimental data fall into this range. Dependence of discharge coefficients on the Reynolds number is good agreement with those suggested in ISO document. The influence of swirl on the discharge coefficients becomes greater as the nozzle throat diameter is enlarged. The discharge coefficient of conical nozzle shows about 4.5% lower discharge coefficients than those of toroidal nozzle, but variation trend with Reynolds number is very similar each other and reproducibility of data is very good.
Experimental study of compression waves propagating porous walls
Kim, Hui-Dong ; Setoguchi, Toshiaki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4036~4043
DOI : 10.22634/KSME-B.19184.108.40.20636
When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates along the tunnel, compressing and accelerating the rest air in front of the wave. At the exit of the tunnel, an impulsive wave is emitted outward toward the surrounding, which causes a positive impulsive noise like a kind of sonic boom produced by a supersonic aircraft. With the advent of high-speed train, such an impulsive noise can be large enough to cause the noise problem, unless some attempts are made to alleviate its pressure levels. In the purpose of the impulsive noise reduction, the present study tested the effect of porous walls on the compression wave propagating into a model tunnel. Experimental results were obtained using a shock tube with an open end. The results showed that the cavity/porous wall is very effective for the compression wave with a large nonlinear effect. The porosity of 30% is most effective for attenuation and pressure gradient reduction of the compression wave front. Also the impulsive noise reduction increases with increasing the length and height of the cavity, compared with the tunnel equivalent diameter.
Planar measurements of OH and
number density in premixed
flame using laser induced pre-dissociative fluorescence
Jin, Seong-Ho ; Nam, Gi-Jung ; Kim, Hei-San ; Jang, Rae-Gak ; Park, Seung-Han ; Kim, Ung ; Park, Gyeong-Seok ; Sim, Gyeong-Hun ; Kim, Gyeong-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4044~4052
DOI : 10.22634/KSME-B.19220.127.116.1144
Planar images of OH and
with tunable KrF excimer laser which has a) 0.5
/ linewidth, b) 0.5 nm tuning range, c) 150 mJ pulse energy, and d) 20 ns pulse width are obtained to determine spatial distributions of OH and
flame. The technique is based on planar laser induced pre-dissociative fluorescence(PLIPF) in which collisional quenching is almost avoided because of the fast pre-dissociation. Dispersed LIPF spectra of OH and
are also measured in a flame in order to confirm the excitation of single vibronic state of OH and
, OH and
are excited on the P
(8) line of the
.PI.(v'||'||'&'||'||'quot;= 0) band and R(17) line of the Schumann-Runge band B
(v'= 0)- X
(v'||'||'&'||'||'quot;= 6), respectively. Dispersed OH and
spectra show an excellent agreement with simulated spectrum and previous works done by other group respectively. It is confirmed that OH widely distributed around flame front area than
Effect of liquid viscosity on internal flow and spray characteristics of Y-jet atomizers
Song, Si-Hong ; Lee, Sang-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 20, issue 12, 1996, Pages 4053~4061
DOI : 10.22634/KSME-B.1918.104.22.16853
Internal flow characteristics within Y-jet atomizers and the local drop size distribution and cross-sectional averaged drop size at the outside were investigated with the liquid and air injection pressures, mixing port length of atomizers, and the liquid properties taken as parameters. To examine the effect of the liquid viscosity, glycerin-water mixtures were used in this study. The liquid viscosity plays only a minor role in determining the internal flow pattern and the spatial distribution shape of drops, but the drop sizes themselves generally increase with increasing of the liquid viscosity. An empirical correlation for the liquid discharge coefficient at the liquid port was deduced from the experimental results; the liquid discharge coefficient strongly depends on the liquid flow area at the mixing point which is proportional to the local volumetric quality(.betha.
), and the volumetric quality was included in the correlation. Regardless of the value of the liquid viscosity, the compressible flow through the gas port was well represented by the polytropic expansion process(k=1.2), and the mixing point pressure could be simply correlated to the aspect ratio(
) of the mixing port and the air/liquid mass flow rate ratio(
) as reported in the previous study.udy.udy.y.