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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
A study on the development of the high efficiency condensing heat exchanger
Lee, Geum-Bae ; Park, Sang-Il ; Park, Jun-Tae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 589~601
DOI : 10.22634/KSME-B.19220.127.116.119
A computer simulation program of a high efficiency condensing heat exchanger is developed. The flue gas flows outside bare tube bundles both in strong cross flow and in weak counter flow and the cooling water inside the tubes. Condensing heat exchangers achieve high efficiency by reducing flue-gas temperatures to a level at which most of the water vapor in the flue gas is condensed and the latent heat associated with phase change of the water is recovered. The computer model has been verified by comparison with measured data. To verify the model, heat transfer coefficient was adjusted, along with the mass transfer diffusion coefficient and pressure drop coefficient, to achieve agreement between predicted and measured data. The efficiencies of heat exchanger increase 2.3 ~ 8.1% by condensations of 6.3 ~ 62.6% of the water vapor in the flue gas.
A Study on the Characteristics of Methane-Air Premixture Combustion and Combustion Radicals (II)
Choe, Su-Jin ; Jeon, Chung-Hwan ; Jang, Yeong-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 602~614
DOI : 10.22634/KSME-B.1918.104.22.1682
In order to evaluate the effects of equivalence ratio, initial pressure and temperature on the laminar flame propagation process, and combustion radicals characteristics, experimental approaches are carried out in methane-air premixture using a constant volume chamber. Local and average radical intensities were measured to determine the time and spatial correlations between each radicals; C
(517 nm) and O
(309 nm) . The results are showed that two kinds of equation were proposed for the cases of continuous flame and intermittent flame type to evaluate actual equivalence ratio using relative intensities with each radicals. Both equations were agreed with actual equivalence ratio within 10% errors range. And schlieren photo and CCD image were compared with flame sizes at equivalence ratio 1.0.o 1.0.
A study on the heat transfer characteristics of swirling flow in a circular sectioned
bend with uniform heat flux
Lee, Sang-Bae ; Gwon, Gi-Rin ; Jang, Tae-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 615~627
DOI : 10.22634/KSME-B.1922.214.171.1245
An experiment was performed to local heat transfer coefficient and Nusselt number in the circular duct of 180.deg. bend for Re=6*10
at swirling flow and non-swirling flow conditions. The test tube with circular section was made by stainless which has curvature ratio 9.4. The wall of test tube was heated directly by electrical power to 3.51 kw and swirling motion of air was produced by a tangential inlet to the pipe axis at the 180 degree. Measurements of local wall temperatures and bulk mean temperature of air are made at four circumferential positions in the 16 stations. The wall temperatures show particularly reduced distribution curve at bend for non-swirling flow but this effect does not appear for swirling flow. Nusselt number distributions for swirling flow which was calculated from the measured wall and bulk temperatures were higher than that of non-swirling flow. Average Nusselt number of swirling flow increased about 90 ~ 100% than that of non-swirling flow whole through the test tube. The Nu/N
values at the station of 90.deg. for non-swirling flow and swirling flow are respectively about 2.5 and 4.8 at Re=6*10
. Also that is good agreement with Said's result for non-swirling flow. flow.
A study on the flow characteristics of laminar wavy film
Kim, Jin-Tae ; Lee, Gye-Han ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 628~636
DOI : 10.22634/KSME-B.19126.96.36.1998
Flow visualization technique incorporating photochromic dye is used to study the flow characteristics of the gravity driven laminar wavy film. The film thickness and wave speed are successfully measured by flow visualization. As the inclination angle increases, the waves have higher peaks and lower substrate thickness. The measured cross stream velocity at the free surface is up to 10% of stream wise velocity, which shows enhanced mixing in the lump of the film. The measured stream wise velocity profiles are close to parabolic profile near the substrate and the peak but show significant velocity defect near the rear side of the wave. The measured wall shear rate distributions show good agreement with the previous workers' numerical results.
Experimental investigation of flow parameters influencing the calibration of five-hole probes
Lee, Sang-U ; Yun, Tae-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 637~649
DOI : 10.22634/KSME-B.19188.8.131.527
Effects of cone angle, pressure-hole orientation and Reynolds number on the five-hole probe calibration have been investigated for eight large-scale conical five-hole probes, which have either perpendicular pressure holes or forward-facing pressure holes for the cone angles of 45 deg, 60 deg, 75 deg and 90.deg. Pitch and yaw angles are changed from -40 deg to +40 deg with an interval of 5 deg, respectively, when the probe Reynolds numbers are 1.77*10
. The result shows that larger cone angle results in more sensitive changes in the calibration coefficients. In the case that the cone angle is 45 deg, the pitch-angle and yaw-angle coefficients of the five-hole probe with the perpendicular pressure holes show a very different trend compared with those of the five-hole probe with the forward-facing pressure holes. On the other hand, when the cone angle is more than 60 deg, each calibration coefficient is nearly independent of the pressure-hole orientation. Additionally, the effects of the Reynolds number on the calibration coefficients are also reported in detail.
Analysis of in-cylinder steady flow for dual-intake-valve gasoline engine using single-frame particle tracking velocimetry
Lee, Chang-Sik ; Lee, Gi-Hyeong ; Im, Gyeong-Su ; Jeon, Mun-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 650~658
DOI : 10.22634/KSME-B.19184.108.40.2060
Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.
Numerical studies for combustion processes and emissions in the DI diesel engines using EGR
Kwon, Y.D. ; Lee, J. C. ; Kim, Y. M. ; Kim, S. W. ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 659~669
DOI : 10.22634/KSME-B.19220.127.116.119
The effects of exhaust gas recirculation on diesel engine combustion and soot/NOx emissions are numerically studied. The primary and secondary atomization is modelled using the wave instability breakup model. Autoignition of a diesel spray is modelled using the Shell ignition model. Soot formation is kinetically controlled and soot oxidation is represented by a model which account for surface chemistry. The NOx formation is based on the extended Zeldovich NOx model. Effects of injection timing and concentration of
on the pollutant formation and the combustion process are discussed in detail.
Numerical analysis for mitigating thermal stratification flow of pressurizer surge horizontal pipe by outside heating
Jeong, Il-Seok ; Kim, Yu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 670~678
DOI : 10.22634/KSME-B.1918.104.22.1680
A method to mitigate the thermal stratification phenomenon of pressurizer surge line is proposed by heating bottom outside of horizontal pipe. Unsteady two dimensional model has been used to numerically investigate an effect of heating the bottom of pipe. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature and streamline profiles of fluids and pipe walls with time are compared with the previous study result. The numerical result of this study shows that the outside heating can relaxate the thermal stratification flow of the pressurizer surge line. Maximum dimensionless temperature difference between hot and cold sections of the pipe inner wall which causes thermal stratification was reduced from 0.514 to 0.424 at dimensionless time 1, 632 and 1, 500 respectively.
An experimental study for the effect of rotational direction on the recovery rate of spilled oil using a belt skimmer
Song, Dong-Eop ; Yun, Gyeong-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 679~690
DOI : 10.22634/KSME-B.1922.214.171.1249
Oil spill over the sea and the river become a serious problem in these days. Two different approaches are used to clean up the spilled oil by means of chemical dispersion and mechanical devices. If it is possible, removing spilled oil using mechanical devices are highly desirable in order not to worry about the secondary contamination from chemical treatment. One of the major unsolved problems using mechanical devices has been the recovery of highly viscous oil spill. So, the systematic experimental data for treating very viscous oil are still wanting. In the present study a series of experiments were carried out to study the effect of the rotational direction of the belt skimmer on the rate of oil recovery using Bunker C oil. Three different situations, namely, upward, downward and up-and-downward pickup rate have been investigated for variable belt speed. The results showed that the rate of oil recovery for downward pickup was much higher than that for upward pickup. The major mechanism to recover the oil using a belt skimmer has been confirmed that oil sticks to the belt surface while moving to the water rather than moving upward. For the removal of spilled oil the optimal belt speed under the present experimental conditions was found to be about 200 ~ 270 mm/s just before the starvation started. The present experimental results would provide the basis for understanding the performance characteristics and physics of various types of skimmers.
Concave surface curvature effect on heat transfer from a turbulent round impinging jet
Im, Gyeong-Bin ; Lee, Dae-Hui ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 691~699
DOI : 10.22634/KSME-B.19126.96.36.1991
The effects of concave hemispherical surface curvature on the local heat transfer from a turbulent round impinging jet were experimentally investigated. The liquid crystal transient method was used for these measurements. This method, which is a variation on the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystals for the measurement of the surface temperature. The Reynolds number ranges from Re=11,000 to 50,000, the nozzle-to- surface distance from L/d=2 to 10, and the surface curvature from D/d=6 to 12.The present results are also compared to those for the flat plate case. In the experiment, the local Nusselt numbers tend to increase in all regions with an increasing surface curvature. The maximum Nusselt number for all Reynolds numbers occurred at L/d .ident. 6 and a second maximum in the Nusselt number occurred at R/d .ident. 2 for both Re=23,000 and Re=50,000 in the case of L/d=2 and for Re=50,000 only in the case of L/d=4. Meanwhile, as the surface curvature increases, the value of the secondary maximum Nusselt number decreases. All the other cases exhibit monotonically decreasing values of the Nusselt number along the curved surface. The stagnation point Nusselt numbers are well correlated with Re, L/d, and D/d.
An experimental study of a flow field generated by a rotating cylinder on a plane moving at free stream velocity
Park, Un-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 700~712
DOI : 10.22634/KSME-B.19188.8.131.520
The flowfield generated by a 2-D rotating cylinder on a plane moving at freestream velocity was experimentally investigated in a wind tunnel to simulate aerodynamic characteristics of rotating wheels of an automobile. In the flowfield around a rotating cylinder at 3*10
, unique mean flow and turbulence characteristics were confirmed by hot-wire measurements as well as frequency analysis, which was supported by flow visualization. In the vicinity of a rotating cylinder, a unique turbulence structure on .root.over bar u'
profiles was formed in hump-like shape at 1 < y/d < 3. A peak frequency which characterized the effect of a rotating cylinder had the same value of the rotation rate of a cylinder. In case of cylinder rotation, the depths of mean velocity -defect and turbulent-shear regions were thickened by 20-40% at 0 < x/d < 10 compared with the case of cylinder stationary. Far downstream beyond x/d > 10, the flowfield generated by a rotating cylinder showed self-similarity in the profiles of mean velocity and turbulence quantities. The effect of a rotating cylinder was independent of its rotation rate and Reynolds number in the measurement range.
Performance and heat transfer of an air conditioning system filled with hydrocarbon refrigerants
Jang, Yeong-Su ; Kim, Min-Su ; No, Seung-Tak ;
Transactions of the Korean Society of Mechanical Engineers B, volume 21, issue 5, 1997, Pages 713~723
DOI : 10.22634/KSME-B.19184.108.40.2063
Performance and heat transfer characteristics of an air conditioning system filled with hydro- carbon refrigerants are experimentally investigated. Single component hydrocarbon refrigerants (propane, isobutane, butane and propylene) and binary mixtures of propane/isobutane and propane/butane are considered as working fluids in the air conditioning system. Performances of each refrigerant are obtained at several compressor speeds and temperature levels of secondary heat transfer fluids. The cooling capacity and the coefficient of performance are obtained as test results. Heat transfer data of selected refrigerants are achieved from overall conductance measurement. Average heat transfer coefficients at different mass fluxes are shown and they are also displayed for different heat capacities of the system. Experimental results show that some hydrocarbon refrigerants have better characteristics than R22.