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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 29, Issue 12 - Dec 2005
Volume 29, Issue 11 - Nov 2005
Volume 29, Issue 10 - Oct 2005
Volume 29, Issue 9 - Sep 2005
Volume 29, Issue 8 - Aug 2005
Volume 29, Issue 7 - Jul 2005
Volume 29, Issue 6 - Jun 2005
Volume 29, Issue 5 - May 2005
Volume 29, Issue 4 - Apr 2005
Volume 29, Issue 3 - Mar 2005
Volume 29, Issue 2 - Feb 2005
Volume 29, Issue 1 - Jan 2005
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An Analysis of Heat and Fluid Flow in the Laser Surface Melting with a Deformed Surface
Kim, Young-Deuk ; Sim, Bok-Cheol ; Kim, Woo-Seung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 1~8
DOI : 10.3795/KSME-B.2005.29.1.001
Laser melting problems with deformed substrates are investigated by axisymmetric numerical simulations. Source-based method is used to solve the energy equation, and the momentum equations are solved in the liquid domain with SIMPLER algorithm. Using a laser beam with a top-hat heat flux distribution, this study is performed to examine the effect of surface deformation, beam power density and surface tension force on the molten pool during laser melting. Surface temperature decreases with increasing surface deformation, while surface velocity increases. It is found that surface deformation, beam power density and surface tension force have a very significant effect on heat transfer and fluid flow during laser melting.
Development of an Ejector System for Operating of Chemical Lasers (III) - Development and Performance Validation of a Full-Scale Ejector System for High Power Chemical Lasers -
Kim, Se-Hoon ; Jin, Jung-kun ; Kwon, Se-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 9~15
DOI : 10.3795/KSME-B.2005.29.1.009
From the geometric parameter study, an optimal ejector design procedure of pressure recovery system for chemical lasers was acquired. For given primary flow reservoir conditions, an up-scaled ejector was designed and manufactured. In the performance test, secondary mass flow rate of 100g/s air was entrained satisfying the design secondary pressure,
. Performance validation of a supersonic ejector system along with an investigation of effects of supersonic diffuser was conducted. Placement of the diffuser at the secondary inlet further reduced diffuser upstream pressure to 7torr. Lastly, the duplicate of apparatus (air 500g/s secondary mass flow rate each) was built and connected in parallel to assess proportionality behavior on a system to handle larger mass flow rate. Test and comparison of the parallel unit demonstrated the secondary mass flow rate was proportional to the number of individual units that were brought together maintaining the lasing pressure.
Cooling Characteristics of a Strip Fin Heat Sink
Park. Cheol-Woo ; Kim. Hyun-Woo ; Jang .Chung-Sun ; Riu. Kap-Jong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 16~26
DOI : 10.3795/KSME-B.2005.29.1.016
Air-cooled heat sinks are employed in many electronic cooling applications since they provide significant heat transfer enhancement and operational flexibility. Strip-shaped fin heat sink is of interest and needs to be investigated as general cooling products for more applicability. The purposes of this study are to evaluate heat sink performance without bypass flow condition and to determine optimal heat sink geometries. The results show that the decreasing rate of thermal resistance of a heat sink decreases with increasing inlet air velocity, and the increasing rate of pressure drop increases with increasing inlet air velocity, but is not affected by input power. The increasing rate of optimal longitudinal fin spacing is larger than that of transverse fin spacing. The strip fin heat sink tested in this study showed better cooling performance compared to that of other plate fin type.matism. 2004; 50(11): 3504-3515.
A Theoretical Study of Photothermal Pulsed Radiometry Method for the Thermal Diffusivity Measurement
Yook, Hyung-Kyu ; Yoo, Jai-Suk ; Kim, Hyun-Jung ; Lee, Kwang-Jai ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 27~34
DOI : 10.3795/KSME-B.2005.29.1.027
We analyze in detail axially symmetric theoretical study for the photothermal pulsed radiometry of a cylindrical model. The theoretical solutions describe the transient infrared radiation from the sample heated by short-duration pulsed heating. In the conventional transmission radiometry technique, the excitation source and the detector are on opposite sides of the sample, otherwise in the new single ended radiometry technique, the excitation source and the detector are on same sides of the sample. The analytical solution described for photothermal radiometry in this study would not need to cut or polish samples to measure the thermal diffusivity. Therefore the radial area and axial thickness of samples are not limited. The effects of excitation pulse duration and the area of heat source are discussed.
Wind Tunnel Test of Smart Un-manned Aerial Vehicle(SUAV) for TR-E2 Configuration
Yoon, Sung-Jun ; Cho, Ta-Hwan ; Chung, Jin-Deog ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 35~45
DOI : 10.3795/KSME-B.2005.29.1.035
TR-E2 configuration designed by Bell Textron was tested in KARI 1-m wind tunnel. To explore aerodynamic characteristics for the given configuration, a
scaled model was fabricated and tested. Wind tunnel test for TR-E2 had been performed by changing the incidence angles of wing and deflection angles of control surfaces. Test result showed that the lower wing incidence angle has more favorable lift to drag ratio compared with original design. Longitudinal and directional characteristics of TR-E2 were found to be stable for the pitch and yaw motions. However, the lateral stability of TR-E2 is not stable for certain control surface deflection.
2-Dimensional Film Cooling Characteristics with the Height Variation of a Stepped Slot Exit
Son, Chang-Ho ; Kim, Tae-Mook ; Lee, Geun-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 46~54
DOI : 10.3795/KSME-B.2005.29.1.046
Film cooling characteristics has been examined numerically for the height variation of a stepped slot exit. In this study, the upstream wall height of the stepped slot exit varies from -2d (d
Combustion Characteristics and Criterion of Quenching Condition in Micro Combustor Parameterized by Initial Pressure and Fuel in the Combustor
Na, Han-Bee ; Lee, Dae-Hoon ; Kwon, Se-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 55~62
DOI : 10.3795/KSME-B.2005.29.1.055
Combustion Characteristics and quenching criteria of micro combustor in various condition was exploited experimentally. Two different gases were used, and various geometric matrixes were considered to figure out quenching characteristic of micro combustor. The micro combustor studied in this study was constant volume, and has cylindrical shape. Geometric parameter of combustor was defined to be combustor height and diameter. The effect of height was exploited parametrically as 1 mm, 2mm and 3mm and the effect of diameter was parameterized to be 7.5mm and 15mm. Three different combustibles. (1) Stoichiometric mixture of methane and are, (2) Stoichiometric mixture of hydrogen and air and (3) Mixture of hydrogen and air with fuel stoichiometry of two were used. Pressure transition during combustion process was recovered. The ratio of maximum pressure to initial pressure responded favorably with the change of height of combustor and the initial pressure, the maximum pressure was also increased. The flame propagation was observed only when a specific condition was satisfied. From the experiment the condition that guarantees stable propagation of flame was tabulated. The tabulated results includes criteria of quenching according to combustor height, combustor diameter, species of fuel and initial pressure.
Numerical Study on Characteristics of Pulsitile Flow by Location of Stenosis in Blood Vessel with the Second Bifurcation
Lee, In-sub ; Ryou, Hong-sun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 63~70
DOI : 10.3795/KSME-B.2005.29.1.063
The main objective of the present study is to predict characteristics of three dimensional pulstitile flow by location of stenosis in blood vessel with the second order bifurcation. The present study simulates the incompressible non-Newtonian laminar blood flows using a Fluent V. 6.0. The Carreau model is employed as the constitutive equation for blood. The numerical simulation carried out at five cases without and with symmetry or asymmetry stenosis. It is found that the no stenosis and stenosis before first bifurcation do not have influence on flow at second bifurcated blood vessel. However, the stenosis after first biburcation has effect on flow at second bifurcated blood vessel.
Nozzle Configurations for Partially Premixed Interacting Jet Flame to Enhance Blowout Limits
Kim, Jin-Hyun ; Lee, Byeong-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 71~79
DOI : 10.3795/KSME-B.2005.29.1.071
For the non-premixed interacting jet flames, it has been reported that if eight small nozzles are arranged along the circle of
times the diameter of single jet, the flames are not extinguished even in 200m/s. In this research, experiments were extended to the partially premixed cases to reduce both flame temperature and NOx emission. Nine nozzles were used- eight was evenly located along the perimeter of the imaginary circle and one at the geometric centre. The space between nozzles, S, the equivalence ratio,
, the exit velocity and the role of the jet from the centre nozzle were considered. Normally, flame was lifted and flame base was located inside the imaginary circle made by the nozzle. As nozzles went away from each other, blowout velocity increased and then decreased. The maximum blowout velocity diminished with the addition of air to the fuel stream. When the fuel and/or oxidizer were not fed through the centre nozzle, the maximum blowout velocity obtained by varying S and
was around 160m/s. Optimum nozzle separation distance at which peak blowout velocity obtained also decreased with
decrease. Flame base became leaner as approaching to the blowout. It seemed that lots of air was supplied to the flame stabilizing region by the entrainment and partially premixing. To approve this idea and to enhance the blowout velocity, fuel was supplied to the centre region. With the small amount of fuel through the centre nozzle, partially premixed flame could be sustained till sonic velocities. It seemed that the stabilizing mechanism in partially premixed interacting flame was different from that of non-premixed case because one was stabilized by the fuel supply through the centre nozzle but the other destabilized.
A Study on Transient Characteristics of Flow Caused by Heat Addition in Supersonic Nozzle
Chung, Jin-Do ; Kim, Jang-Woo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 80~86
DOI : 10.3795/KSME-B.2005.29.1.080
This study presents numerical solutions of the two-dimensional Navier-Stokes equations for supersonic unsteady flow in a convergent-divergent nozzle with heat addition. The TVD scheme in generalized coordinates is employed in order to calculate the moving shock waves caused by thermal choking. We discuss on transient characteristics, start and unstart phenomena, fluctuations of specific thrust caused by thermal choking and viscous effects. We prove that the control of separation of boundary layer is the most important key problem to prevent the thermal choking.
Development of an Electrical Capacitance Tomography Code for Analysis of Two-Phase Flow in the Rectangular Pipe
Lee, Kyoung-Hwang ; Lee, Jae-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 87~94
DOI : 10.3795/KSME-B.2005.29.1.087
A computer code for Electrical Capacitance Tomography (ECT) is developed to sense the cross sectional phase distribution of two-phase flow in the rectangular pipe in which the tomography sensor furnished by the insulated wall, electrodes, and electric field screen. The computer code had two steps for the image reconstruction. In the forward projection step, the sensitivity matrix was constructed based on the electric field calculated by the finite difference method. In the backward projection step, the sensitivity matrix and the measured capacitances were used to reconstruct the cross sectional image. Several algorithms including LBP, TR, ITR, and PLI were employed to find the proper one for the two-phase flow analysis. Since the dielectric constant of the water in two-phase flow is sensitive to the thermal parameter such as, temperature and pressure, the developed code was evaluated to find their accuracy, speed of calculation, and sensitivity to the variation of the dielectric constant. It was found that the iterative methods are superior to the direct methods for the image reconstruction, and the PLI method was the best in the variation of the dielectric constants.
A Numerical Study on Acoustic Behavior in Gas Turbine Combustor with Acoustic Resonator
Park, I-Sun ; Sohn, Chae-Hoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 95~102
DOI : 10.3795/KSME-B.2005.29.1.095
Acoustic behavior in gas turbine combustor with acoustic resonator is investigated numerically by adopting linear acoustic analysis. Helmholtz-type resonator is employed as acoustic resonator to suppress acoustic instability passively. The tuning frequency of acoustic resonator is adjusted by varying its length. Through harmonic analysis, acoustic-pressure responses of chamber to acoustic excitation are obtained and the resonant acoustic modes are identified. Acoustic damping effect of acoustic resonator is quantified by damping factor. As the tuning frequency of acoustic resonator approaches the target frequency of the resonant mode to be suppressed. mode split from the original resonant mode to lower and upper modes appears and thereby complex patterns of acoustic responses show up. Considering mode split and damping effect as a function of tuning frequency, it is desirable to make acoustic resonator tuned to broad-band frequencies near the maximum frequency of those of the possible upper modes.
The Experimental Research on Periodic Airflow in Human Nasal Cavity
Shin, Sok-Jea ; Kim, Sung-Kyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 103~109
DOI : 10.3795/KSME-B.2005.29.1.103
Airflow in the nasal cavity of a normal Korean adult is investigated experimentally by tomographic PIV measurement. Knowledge of airflow characteristics in nasal cavities is essential to understand the physiology and pathology aspects of nasal breathing. Several studies have utilized physical models of the healthy nasal cavity to investigate the relationship between nasal anatomy and airflow. All of these researches on nasal airflow are under the condition of constant flow-rate. In this study, nasal cavity flow with the physiological period is investigated by tomographic PIV, for the first time. A pumping system that can produce the periodic flow is created. Thanks to a new method for the model casting by a combination of the rapid prototyping and curing of clear silicone, a transparent rectangular box containing the complex nasal cavity can be made for PIV, The CBC PIV algorithm is used for analysis. Phase-averaged mean and RMS velocity distributions are obtained for inspirational and expiration nasal airflows. The comparison with the constant flow case is appreciated. There exist many flow patterns depending on each phase.
Particle Beam Focusing Using Radiation Pressure
Kim, Sang-Bok ; Park, Hyung-Ho ; Kim, Sang-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 110~115
DOI : 10.3795/KSME-B.2005.29.1.110
A novel technique for fine particle beam focusing under the atmospheric pressure is introduced using a radiation pressure assisted aerodynamic lens. To introduce the radiation pressure in the aerodynamic focusing system, a 25m plano-convex lens having 2.5mm hole at its center is used as an orifice. The particle beam width is measured for various laser power, particle size, and flow velocity. In addition, the effect of the laser characteristics on the beam focusing is evaluated comparing an optical tweezers type and pure gradient force type. For the pure aerodynamic focusing system, the particle beam width was decreased as increasing particle size and Reynolds number. Using the optical tweezers type, the particle beam width becomes smaller than that of the pure aerodynamic focusing system about
for PSL particle size of
, respectively. Particle beam width was minimized around the laser power of 0.2W. However, as increasing the laser power higher than 0.4W, the particle beam width was increased a little and it approached almost a constant value which is still smaller than that of the pure aerodynamic focusing system. For pure gradient force type, the reduction of the particle beam width was smaller than optical tweezers type but proportional to laser power. The radiation pressure effect on the particle beam width is intensified as Reynolds number decreases or particle size increases relatively.
A Study on the Performance of Condensation Heat Transfer for Various Working Fluid of Two-Phase Closed Thermosyphons with Various Helical Grooves
Han, Kyu-Il ; Cho, Dong-Hyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 116~122
DOI : 10.3795/KSME-B.2005.29.1.116
This study concerns the performance of condensing heat transfer in two-phase closed thermosyphons with various helical grooves. Distilled water, methanol, ethanol have been used as the working fluid. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A experimental study was carried out for analyzing the performances of having 50, 60, 70, 80, 90 helical grooves. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphons is also tested for the comparison. The type of working fluid and the numbers of grooves of the thermosyphons with various helical grooves have been used as the experimental parameters. The experimental results have been assessed and compared with existing theories. The results show that the type of working fluids are very important factors for the operation of thermosyphons. And the maximum enhancement (i.e. the ratio of the heat transfer coefficients the helical thermosyphons to plain thermosyphons) is
Development of Digital Holographic PIV Technique and Its Application
Kim, Seok ; Lee, Sang-Joon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 123~130
DOI : 10.3795/KSME-B.2005.29.1.123
A digital in-line holographic particle image velocimetry (HPIV) which can be applied to measure three-dimensional velocity fields of turbulent flows was developed. There are three different implementation methods of HPIV: traditional film-based HPIV, intermediate HPIV and digital HPIV. The traditional film-based HPIV and intermediate HPIV method is rather troublesome to do experiments and takes long calculation time, compared with the digital HPIV, Configuration of the digital in-line HPIV is simple and the data processing routine is similar to conventional 2D PIV methods. The digital HPIV velocity field measurement consists of four steps: recording, numerical reconstruction, particle extraction and velocity extraction. In the velocity extraction process, we improved PTV algorithm to extract the displacement of particle each placed in 3D space. The developed digital in-line HPIV system was applied to a vertical jet flow. The 3D velocity vectors measured by the digital HPIV method in the near field are in a good agreement with 2D PIV results.
Theoretical and Simulation Study of Thermo-Osmosis of Liquid in Microchannel
Han, Min-Sub ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 131~138
DOI : 10.3795/KSME-B.2005.29.1.131
Thermo-osmosis of liquids in a microscale channel is investigated by theoretical and simulation study. From the basic set of conservation equations, the temperature and velocity distributions are derived in the function of the given temperatures and pressure gradient. The pressure gradient for a given temperature gradient is then obtained by the molecular simulation. It is shown that the temperature gradient tangential to the surface induces the pressure gradient and thus the flow in the interfacial region between the liquid and channel surface. The thermo-osmotic flow is proportional to the applied temperature gradient, and the factor of proportionality depends on temperature and intermolecular potential. The origin and characteristics of the phenomenon are discussed in molecular details.
Numerical Study on Uniform-Shear Flow Over a Circular Cylinder
Choi, Won-Ho ; Kang, Sang-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 139~150
DOI : 10.3795/KSME-B.2005.29.1.139
The present study has numerically investigated two-dimensional laminar flow over a circular cylinder with a uniform planar shear, where the free-stream velocity varies linearly across the cylinder. Numerical simulations using the immersed boundary method are performed for the ranges of
, and B
Thermal Characteristics of Foams and Discharge of Fire-Protection Foam Spray Nozzle
Kim, Hong-Sik ; Kim, Youn-Jea ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 151~158
DOI : 10.3795/KSME-B.2005.29.1.151
A characteristic of discharge for a foam spray nozzle with various parameters was investigated. The discharge patterns from a fire foam spray nozzle are important to evenly spray over a maximum possible floor area. Two parameters of a foam spray nozzle were chosen, and compared with those from the standard one. Also, in order to evaluate the performance of discharged foam agents used to protect structures from heat and fire damages, the thermal characteristics of fire-protection foams were experimentally investigated. A simple repeatable test for fire-protection foams subjected to fire radiation was developed. This test involves foam generation equipment, a fire source for heat generation, and data acquisition techniques. Results show that the bubble size of foam is increased by large inside diameter of orifice or closed air hole, but phenomenon of discharge angle and expansion ratio is opposite. For the case of the open air hole, liquid film of a circular cone discharges with formation, growth, split and fine grain. In case of the closed air hole, a pillar of foam solution discharges with that. Though the temperature gradient in the foam increases with increased foam expansion ratio. it is not change with increased intensity of heat flux.
A Study on the Phenomena at a Liquid-Vapor Interface by the Molecular Dynamics Method
Choi, Hyun-Kue ; Song, Chi-Sung ; Kim, Hye-Min ; Lee, Jung-Hye ; Choi, Soon-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 29, issue 1, 2005, Pages 159~168
DOI : 10.3795/KSME-B.2005.29.1.159
In recent studies, it was reported that there existed the temperature discontinuity at a liquid-vapor interface in an equilibrium state. However, from the viewpoint of the classical thermodynamics, it is highly questionable result although considering that the experiments related with a boundary layer is very difficult due to the extremely thin thickness of it. To clarify whether the temperature discontinuity over a liquid-vapor interface really exists, the computer simulations were performed. From the simulation results, it could be concluded that the misconception in a temperature calculation might result in non-uniform temperature distributions over an interface under an equilibrium state