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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 25, Issue 12 - Dec 2001
Volume 25, Issue 11 - Nov 2001
Volume 25, Issue 10 - Oct 2001
Volume 25, Issue 9 - Sep 2001
Volume 25, Issue 8 - Aug 2001
Volume 25, Issue 7 - Jul 2001
Volume 25, Issue 6 - Jun 2001
Volume 25, Issue 5 - May 2001
Volume 25, Issue 4 - Apr 2001
Volume 25, Issue 3 - Mar 2001
Volume 25, Issue 2 - Feb 2001
Volume 25, Issue 1 - Jan 2001
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Velocity Field Measurements of a Vertical Turbulent Buoyant Jet Using a PIV Technique
Sin, Dae-Sik ; Yun, Jeong-Hwan ; Lee, Sang-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 611~618
DOI : 10.22634/KSME-B.2001.25.5.611
The flow characteristics of a turbulent buoyant jet were experimentally investigated using a single-frame PIV system. The Reynolds number based on the nozzle exit velocity and nozzle diameter was about Re=5
. The instantaneous velocity fields in the streamwise plane passing the jet axis were measured in the near field X/D <11 with and without the temperature gradient. By ensemble averaging the instantaneous velocity fields, the spatial distributions of mean velocity, vorticity, and higher-order statistics up to third order were obtained. The temperature difference of 10
does not affect a significant influence to the flow structure in the near field, but the total entrainment rate is increased slightly. The entrainment rate shows a linear variation with the streamwise distance in the region after X/D=5.0.
A Study of Natural Convection Heat Transfer in a Composed Rectangular-Parallelogrammic Enclosure with a Guide Vane
Jang, Yeong-Geun ; Jo, Un ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 619~626
DOI : 10.22634/KSME-B.2001.25.5.619
The present experimental and numerical study investigate flow and natural convection heat transfer characteristics of a composed rectangular-parallelogrammic enclosure with a guide vane. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a modified SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term. In this results of experimental study, the natural convection heat transfer characteristics was well coincided with conclusions of other earlier experimental researches and numerical analysis.
Characteristics of Impinging Diesel Spray on the Heated Flat Wall in High Temperature and High Pressure Environments
Im, Gyeong-Hun ; Lee, Bong-Su ; Kim, Jong-Hyeon ; Gu, Ja-Ye ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 627~633
DOI : 10.22634/KSME-B.2001.25.5.627
Characteristics of a diesel spray impingement with the variation of ambient temperature, wall temperature and ambient pressure were investigated through shadowgraphy method by using high speed camera. The radial penetration of spray was increased with ambient temperature and wall temperature. It is resulted from the decrease of ambient gas density caused by the increase of temperature. The height of spray was also increased with ambient temperature and wall temperature, because the height of stagnate region is noticeably increased, although height of wall jet vortex is decreased. At the same ambient pressure, the area ratio of impinging spray of room temperature environment to high temperature environment was increased, as the temperature difference between room temperature and high temperature increases. And the increment of area ratio was higher at low ambient pressure than high ambient pressure.
Development of 1/60th Scale Moving Model Rig Using the Compressed Air Launcher and One-Wire Guidance System of Train Model
Kim, Dong-Hyeon ; O, Il-Geun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 634~644
DOI : 10.22634/KSME-B.2001.25.5.634
The test facility of a 1/60-scale model for train-tunnel systems has been recently developed to investigate the effects of tunnel portal shapes, hood shapes and air-shafts for reducing the micro-pressure waves radiating towards the surroundings from the tunnel exit. The present test rig has been advanced from a 1/70-scale facility at NLR in Netherlands. The NLR test rig has the two-wise guidance system that needs two ears attached on the external surface of a model train nose. Therefore, their train models have irregular nose shapes. The main characteristics of the present facility are that the train model is guided by only one wire from the compressed air launcher to the absorber parts of test facility and the wire guidance hole is located at the axial center of a train model. In the present test rig, after a train model is launched, the air jet from the launcher does not enter the tunnel model. Experimental results were compared with numerical predictions to prove the performance of the test facility.
The Effect of Wake-Induced Periodic Unsteadiness on Heat Transfer in the Transitional Boundary Layer Around NACA0012 Airfoil
Jeong, Ha-Seung ; Lee, Jun-Sik ; Gang, Sin-Hyeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 645~652
DOI : 10.22634/KSME-B.2001.25.5.645
Heat transfer data are presented which describe characteristics of the transitional thermal boundary layers on the NACA0012 airfoil with upstream wakes. The wakes are generated periodically by circular cylindrical rods which rotate around the airfoil like a squirrel cage. The unsteady wakes simulate those produced by the upstream rotating blade rows in axial turbomachines. The pressure or suction side of the airfoil is also simulated according to the rotating direction of circular rods. As the Reynolds number and the number of rotating rods increase, the boundary layer transition occurs earlier and the Nusselt number increases. The difference of heat transfer coefficient is less on the pressure side than on the suction side. At a constant Reynolds number, the Nusselt number is larger and smaller, respectively, before and after transition as the Strouhal number increases.
Experiments on Operation Characteristics of In-Water Harvest-Type Ice Storage System
Choe, In-Su ; Kim, Jae-Dol ; Yun, Jeong-In ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 653~659
DOI : 10.22634/KSME-B.2001.25.5.653
This paper is concerned with the development of a new method for making and separating ice in-water and saving floated ice by installing an evaporation panel in an ice storage tank. The new method shows very good heat transfer efficiency than that of the convectional method. It is because the evaporation panel is directly contacted with water in the storage tank. The experiments were performed by varying inlet and outlet refrigerant temperatures of its evaporator. From the experimental results, the operating characteristics of in-water harvest-type ice storage system were investigated by measuring temperature and pressure at each point of the ice storage system and power required to operating compressor respect to the changes of the inlet and outlet refrigerant temperature of evaporator. It can be think that defrost frequency decreased and heavy ice created as the refrigerant temperature of evaporator outlet and defrost setting temperature is low so gotten result can effect to release efficiency. Also, consumption power, condensing heat quantity, refrigerating capacity and performance efficiency decreased as time goes by. Therefore, these results provide the basic data for system optimization, performance improvement and the possibility of application to other fields.
Characteristics of Ultrafine SiO
Particle Synthesized by Electro-Hydrodynamic Spray Injection in a Furnace
Yun, Jin-Uk ; Yang, Tae-Hun ; An, Gang-Ho ; Choe, Man-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 660~665
DOI : 10.22634/KSME-B.2001.25.5.660
Ultrafine particles have been widely used in many high technology industrial areas. The spherical nonagglomerated and uniform nanometer-size SiO
particles are synthesized by the direct injection of TEOS(Tetraethyorthosilicate) using electro-hydrodynamic spraying method. Electro-hydrodynamic spraying can generate submicron-size TEOS droplets having high electric charges by applying a high electric field between the liquid injection nozzle and the reaction tube. These TEOS droplets are evaporated, and thermally decomposed or oxidized to produce nanometresized SiO
particles in the reaction tube. Spherical, nonagglomerated and ultrafine particles are generated in various conditions and examined by using SEM and SMPS. As the total gas flow rate in the furnace changes from 1.5 lpm, the mean diameter of SiO
particle decreases from 120 nm to 68 nm. The synthesized particle charging fractions are also investigated.
Effects of Hydrophilic Surface Treatment on Evaporation Heat Transfer at the Outside Wall of Enhanced Tubes
Park, No-Seong ; Hwang, Gyu-Dae ; Kim, Ho-Yeong ; Gang, Byeong-Ha ; Jeong, Jin-Taek ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 666~672
DOI : 10.22634/KSME-B.2001.25.5.666
Experiments have been carried out to investigate the evaporation heat transfer characteristics of various tubes on which hydrophilic surface treatment using plasma was employed. Spiral, corrugated and low-finned tubes were selected as test tubes. The evaporator tubes were bundled to form three rows of tubes connected in series, with each row being 400mm long. The results obtained indicate that hydrophilic treated tubes tested exhibit better evaporation heat transfer performance as compared with untreated tubes. It is found that the high wettability of the surface obtained through hydrophilic treatment induces film flow onto the tubes during the evaporation process, while sessile drops are formed on untreated tubes.
Inverse Estimation of Thermal Properties for APC-2 Composite
Jeong, Beop-Seong ; Kim, Seon-Gyeong ; Kim, Hui-Jun ; Lee, U-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 673~679
DOI : 10.22634/KSME-B.2001.25.5.673
The objective of this work is to estimate the temperature dependent thermal properties of the APC-2 composite using a inverse parameter estimation technique. The present inverse method features the estimation of the thermal conductivity and the volumetric heat capacity, which are dependent on the temperature inside the composite. Furthermore, the thermal conductivity is directionally dependent because of the aniosotropy of the composite. An on-line temperature measurement system with a suitable method of heating is built. A composite slab is fabricated using thermoplastic prepreg for the investigation. The corresponding computer code for evaluating the thermal properties inversely using the temperature reading transmitted from the measurement system is developed. The parameterized form is used for the rapid and stable estimation. The modified Newtons method is adopted for the solution technique of the inverse analysis. The estimated results are compared with the measured data from a previous study for the verification.
A Study on the Spin-up Flow in a Rectangular Container by Using Ekman Pumping Models
Choe, Yun-Hwan ; Park, Jun-Gwan ; Seo, Yong-Gwon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 680~687
DOI : 10.22634/KSME-B.2001.25.5.680
In this study, spin-up flows in a rectangular container are analysed both numerically and experimentally. In the numerical computation, we use two Ekman pumping models, the classical leading order and the first order. We also compared our results with those obtained for the case without a pumping model. Effect of two parameters, Reynolds number and the Rossby number on the flow evolution is studied. The first order and the leading order Ekman pumping models are in good agreement with the experimental result compared with the non-Ekman pumping model. Attention is given to the merging of two cyclonic vortices.
Vaporizing Characteristics of Spray from Two Different GDI Injectors
Choe, Dong-Seok ; Kim, Deok-Jul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 688~696
DOI : 10.22634/KSME-B.2001.25.5.688
Vaporizing characteristics of two GDI injectors with different spray angles were investigated using exciplex fluorescence method. Injector I has narrower spray angle, while injector II has wider one. The exciplex system of fluorobenzene and DEMA in a non-fluorescing base fuel of hexane was employed. In quantifying concentration of fuel vapor, quenching of concentration and temperature was corrected. Droplet size and velocity were also measured by PDPA under non-vaporizing condition. From obtaining the images of liquid and vapor phases, vaporizing GDI sprays could be divided as two regions: cone and mixing regions. For injector I, vortex region was not developed. High concentration of fuel vapor due to vaporization of many fine droplets was distributed near the spray axis. For injector II, droplets with the diameter of about 10
m were distributed in the vortex region. The vortex region had high concentration of fuel vapor due to vaporization of these droplets. Particularly, higher and lower concentrations of fuel vapor were balanced at 2ms after the start of injection for injector II.
Numerical Study of Wavy Taylor-Couette Flow(I) -Without an Axial Flow-
Hwang, Jong-Yeon ; Yang, Gyeong-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 697~704
DOI : 10.22634/KSME-B.2001.25.5.697
The flow between two concentric cylinders, with the inner one rotating, is studied using numerical simulation. This study considers the identical flow geometry as in the experiments of Wereley and Lueptow[J. Fluid Mech., 364, 1998]. They carried out experiment using PIV to measure the velocity fields in a meridional plane of the annulus in detail. When Taylor number increases over the critical one, the flow instability caused by curved streamlines of the tangential flow induces Taylor vortices in the flow direction. As Taylor number further increases over another critical one, the steady Taylor vortices become unsteady and non-axisymmetrically wavy. The velocity vector fields obtained also show the same flow features found in the experiments of Wereley and Lueptow.
Numerical Study of Wavy Taylor-Couette Flow (II) -With an Axial Flow-
Hwang, Jong-Yeon ; Yang, Gyeong-Su ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 705~712
DOI : 10.22634/KSME-B.2001.25.5.705
The flow between two concentric cylinders, with the inner one rotating and with an imposed pressure-driven axial flow, is studied using numerical simulation. The case without the axial flow was investigated in the preceding paper. This study considers the identical flow geometry as in the experiments of Wereley and Lueptow[Phys. Fluid, 11(12), 1999]. They carried out experiments using PIV to measure the velocity fields in a meridional plane of the annulus in detail. When an axial flow is imposed, the critical Taylor number is increased. The axial flow stabilizes the flow field and decreases the torque required to rotate the inner cylinder. The velocity vector fields obtained also show the same flow features found in the experiments of Wereley and Lueptow.
Flow Structure of Conical Vortices Generated on the Roof of a Rectangular Prism
Kim, Gyeong-Cheon ; Ji, Ho-Seong ; Seong, Seung-Hak ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 713~721
DOI : 10.22634/KSME-B.2001.25.5.713
Characteristics of the conical vortices on the roof corner of a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. The Reynolds number based on the free stream velocity and the height of the model was 5.3
. The mean, instantaneous velocity vector fields, vorticity fields, and turbulent kinetic energy distribution were measured for two different angles of attack, 30
. The PIV measurements clearly observed not only the conical main vortex and the secondary vortex but also the tertiary vortex which is firstly reported in this paper. Asymmetric formation of the corner vortex for the case of 30
angle of attack produces relatively the high magnitude of vorticity and turbulent kinetic energy around the bigger vortex which generates the peak suction pressure on the roof. Fairly symmetric features of the roof vortex are observed in the case of 45
angle of attack, however, the dynamic characteristics are proved to be asymmetric due to the rectangular shape of the roof.
Control of Impinging Jet Heat Transfer Using Mesh Screens
Jo, Jeong-Won ; Lee, Sang-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 722~730
DOI : 10.22634/KSME-B.2001.25.5.722
The local heat transfer of an axisymmetric submerged air jet impinging on a heated flat plate is investigated experimentally with the variation of mesh-screen solidity. The screen installed in front of the nozzle exit modifies the flow structure and local heat transfer characteristics. The mean velocity and turbulence intensity profiles of streamwise velocity component are measured using a hot-wire anemometry. The temperature distribution on the heated flat surface is measured with thermocouples. The smoke-wire flow visualization technique was employed to understand the near-field flow structure qualitatively for different mesh screens. Large-scale toroidal vortices and high turbulence intensity enhance the heat transfer rate in the stagnation region. For a higher solidity, turbulence intensity become higher which increases the local heat transfer at small nozzle-to-plate spacings such as L/D<6. The local and average Nusselt numbers of impinging jet from the
(sub)s=0.83 screen at L/D=2 are about 5.6∼7.5% and 7.1% larger than those for the case of no screen, respectively. For the nozzle-to-plate spacings larger than 6, however, the turbulence intensities for all tested screens approach to an asymptotic curve and the mean velocity along the jet centerline decreases monotonically. As the nozzle-to-plat spacing increases for high solidity screens, the heat transfer rate decreases due to the reduction in turbulence intensity and jet momentum.
Numerical Study on the Similarity between the Fully Developed Turbulent Flow in an Orthogonally Rotating Square Duct and that in a Stationary Curved Square Duct
Lee, Gong-Hui ; Baek, Je-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 731~740
DOI : 10.22634/KSME-B.2001.25.5.731
A numerical study on the quantitative analogy between the fully developed turbulent flow in a straight square duct rotating about an axis perpendicular to that of the duct and that in a stationary curved duct of square cross-section is carried out. In order to clarify the similarity of the two flows, dimensionless parameters K(sub)TR=Re(sup)1/4/√Ro and Rossby number, Ro, in a rotating straight duct flow were used as a set corresponding to K(sub)TC=Re(sup)1/4/√λ and curvature ratio, λ, in a stationary curved duct flow so that they have the same dynamical meaning as those of the fully developed laminar flows. For the large values of Ro or λ, it is shown that the flow field satisfies the asymptotic invariance property, that is, there are strong quantitative similarities between the two flows such as flow patterns and friction factors for the same values of K(sub)TR and K(sub)TC.
Electrodynamic Behavior of a Charged Particle among Two-Dimensional Quadrupole Electrodes
Park, Seok-Joo ; Lim, Jeong-Hwan ; Kim, Sang-Do ; Choi, Ho-Kyung ; Park, Hyun-Seol ; Park, Young-Ok ; McMurry, Peter-H. ;
Transactions of the Korean Society of Mechanical Engineers B, volume 25, issue 5, 2001, Pages 741~749
DOI : 10.22634/KSME-B.2001.25.5.741
An inhomogeneous hyperbolic electric field is established among two-dimensional quadrupole electrodes to which an ac voltage is applied. Conditions under which charged particles are focused into a narrow axis region of the plug laminar flow are discussed. The aerodynamic forces influence the behavior of the charged particles in the quadrupole electric field. We derived the dimensionless equations of motion of a charged particle in the alternating quadrupole electric field, and discussed particle trajectories and focusing performance in terms of two dimensionless parameters, which are functions of particle size, operating pressure, and the amplitude and frequency of applied AC voltage, with the results of numerical simulations and experiments.