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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 30, Issue 12 - Dec 2006
Volume 30, Issue 11 - Nov 2006
Volume 30, Issue 10 - Oct 2006
Volume 30, Issue 9 - Sep 2006
Volume 30, Issue 8 - Aug 2006
Volume 30, Issue 7 - Jul 2006
Volume 30, Issue 6 - Jun 2006
Volume 30, Issue 5 - May 2006
Volume 30, Issue 4 - Apr 2006
Volume 30, Issue 3 - Mar 2006
Volume 30, Issue 2 - Feb 2006
Volume 30, Issue 1 - Jan 2006
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Experimental Investigation on Flow Characteristics of Chicken Blood in a Micro Tube Using a Micro-PIV Technique
Yeo, Chang-Sub ; Ji, Ho-Seong ; Lee, Sang-Joon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1027~1034
DOI : 10.3795/KSME-B.2006.30.11.1027
In order to investigate flow characteristics of chicken blood in a micro tube of 100
m in diameter, in-vitro experiments were carried out using a micro-PIV technique. The micro-PIV system consists of a microscope, 2-head Nd:YAG laser, 12 bit cooled CCD camera and a delay generator. Chicken blood with 40% hematocrit was supplied into a micro tube using a syringe pump. The blood flow shows clearly the cell free layer near the tube wall and its thickness is increased with increasing the flow speed. The hemorheological characteristics of chicken blood, including shear rate and shear stress were estimated from the PIV velocity field data obtained. Since the aggregation index of chicken blood is less than 50% of human blood, non-Newtonian flow characteristics of chicken blood are smaller than those of human blood. As the flow rate increases, the degree of flatness in the velocity profile at the center region is decreased and the parabola-shaped shear stress distribution becomes to have a linear profile. Under the same flow rate, chicken blood shows higher shear stress, compared with human blood.
Two-phase Pressure Drop in a Horizontal Rectangular Microchannel
Huh, Cheol ; Kim, Moo-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1035~1042
DOI : 10.3795/KSME-B.2006.30.11.1035
An experimental investigation was performed to study two-phase pressure drop of deionized water in a microchannel. Measurement and evaluation of two-phase frictional pressure gradient were carried out using a single horizontal rectangular microchanne1 having a hydraulic diameter of
. Tests were performed for mass fluxes of 90, 169, and 267
s and heat fluxes of 200-700
. Test results showed that the measured two-phase frictional pressure gradient increased with the mass flux and vapor quality. Most macro-channel correlations of two-phase frictional pressure gradient did not provide reliable predictions except under certain limited conditions.
Flow Boiling Heat Transfer in a Horizontal Rectangular Microchannel
Huh, Cheol ; Kim, Moo-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1043~1050
DOI : 10.3795/KSME-B.2006.30.11.1043
An experimental investigation was performed to study flow boiling heat transfer of deionized water in a microchannel. Measurement and evaluation of boiling heat transfer coefficients were carried out using a single horizontal rectangular microchannel having a hydraulic diameter of
. Tests were performed for mass fluxes of 90, 169 and 267
s and heat fluxes of 200-700
. Test results showed that the measured boiling heat transfer coefficients had no dependence on mass flux and vapor quality. Most macro-channel correlations of boiling heat transfer coefficient did not provide reliable predictions.
The PIV Measurements on the Respiratory Gas Flow in the Human Airway
Kim, Sung-Kyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1051~1056
DOI : 10.3795/KSME-B.2006.30.11.1051
The mean and RMS velocity field of the respiratory gas flow in the human airway was studied experimentally by particle image velocimetry (PIV). Some researchers investigated the airflow for the mouth breathing case both experimentally and numerically. But it is very rare to investigate the airflow of nose breathing in a whole airway due to its geometric complexity. We established the procedure to create a transparent rectangular box containing a model of the human airway for PIV measurement by combination of the RP and the curing of clear silicone. We extend this to make a whole airway including nasal cavities, larynx, trachea, and 2 generations of bronchi. The CBC algorithm with window offset (64
64 to 32
32) is used for vector searching in PIV analysis. The phase averaged mean and RMS velocity distributions in Sagittal and coronal planes are obtained for 7 phases in a respiratory period. Some physiologic conjectures are obtained. The main stream went through the backside of larynx and trachea in inspiration and the frontal side in expiration. There exist vortical motions in inspiration, but no prominent one in expiration.
Development of the 3-D Bulk Motion Index for In-Cylinder Flow Induced by Induction System (I) - Based on the 3-D CFD Simulation Results -
Yun, Jeong-Eui ; Nam, Hyeon-Sik ; Kim, Myung-Hwan ; Min, Sun-Ki ; Park, Pyeong-Wan ; Kim, Ki-Seong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1057~1065
DOI : 10.3795/KSME-B.2006.30.11.1057
In order to figure out the physical meaning of 3-D angular flow index for in-cylinder bulk motion, CFD analysis for the swirl and tumble steady flow test rig were made using commercial package STAR-CD. Computer simulations and rig tests on some kinds of induced flow conditions were carried out. Finally, based on the comparison between the simulated results and measured results, the physical meaning of 3-D angular flow index
composed of swirl and tumble coefficients measured by steady flow test rig was described.
Development of the 3-D Bulk Motion Index for In-Cylinder Flow Induced by Induction System (II) - Based on the Steady Flow Rig Test Results -
Yun, Jeong-Eui ; Nam, Hyeon-Sik ; Kim, Myung-Hwan ; Min, Sun-Ki ; Park, Pyeong-Wan ; Kim, Ki-Seong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1066~1073
DOI : 10.3795/KSME-B.2006.30.11.1066
Recently, because the variable induction systems are adopted to intake system, in-cylinder flow induced by induction system is very complex. Therefore it is very difficult to describe the in-cylinder bulk flow characteristics using the conventional swirl or tumble coefficient. In this study, in order to clarify the 3-D angular flow characteristics of in-cylinder bulk motion in the developing process of variable induction system, we introduced the new 3-D angular flow index, angular flow coefficient(
) Finally, to confirm the index, we carried out the steady flow rig test for intake port of test engine varying valve lift on the test matrix.
Detailed Heat Transfer Characteristics on Rotating Turbine Blade
Rhee, Dong-Ho ; Cho, Hyung-Hee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1074~1083
DOI : 10.3795/KSME-B.2006.30.11.1074
In the present study, the effect of blade rotation on blade heat transfer is investigated by comparing with the heat transfer results for the stationary blade. The experiments are conducted in a low speed annular cascade with a single stage turbine and the turbine stage is composed of sixteen guide vanes and blades. The chord length and the height of the tested blade are 150 mm and about 125 mm, respectively. The blade has a flat tip and the mean tip clearance is 2.5% of the blade chord. A naphthalene sublimation method is used to measure detailed mass transfer coefficient on the blade. For the experiments, the inlet Reynolds number is
, which results in the blade rotation speed of 255.8 rpm. Blade rotation induces a relative motion between the blade and the shroud as well as a periodic variation of incoming flow. Therefore, different heat/mass transfer patterns are observed on the rotating blade, especially near the tip and on the tip. The relative motion reduces the tip leakage flow through the tip gap, which results in the reduction of the tip heat transfer. However, the effect of the tip leakage flow on the blade surface is increased because the tip leakage vortex is formed closer to the surface than the stationary case. The overall heat/mass transfer on the shroud is not affected much by the blade rotation.
Aerodynamic Characteristics and Shape Optimization of Airfoils in WIG Craft Considered Ground Effect
Lee, Ju-Hee ; Kim, Byeong-Sam ; Park, Kyoung-Woo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1084~1092
DOI : 10.3795/KSME-B.2006.30.11.1084
Shape optimization of airfoil in WIG craft has been performed by considering the ground effect. The WIG craft should satisfy various aerodynamic characteristics such as lift, lift to drag ratio, and static height stability. However, they show a strong trade-off phenomenon so that it is difficult to satisfy aerodynamic properties simultaneously. Optimization is carried out through the multi-objective genetic algorithm. A multi-objective optimization means that each objective is considered separately instead of weighting. Due to the trade-off, pareto sets and non-dominated solutions can be obtained instead of the unique solution. NACA0015 airfoil is considered as a baseline model, shapes of airfoil are parameterized and rebuilt with four-Bezier curves. There are eighteen design variables and three objective functions. The range of design variables and their resolutions are two primary keys for the successful optimization. By two preliminary optimizations, the variation can be reduced effectively. After thirty evolutions, the non-dominated pareto individuals of twenty seven are obtained. Pareto sets are all the set of possible and excellent solution across the design space. At any selections of the pareto set, these are no better solutions in all design space.
A Numerical Study on Combustion-Stability Rating of Impinging-Jet Injector Using Air-Injection Technique
Sohn, Chae-Hoon ; Park, I-Sun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1093~1100
DOI : 10.3795/KSME-B.2006.30.11.1093
Combustion stability rating of jet injector is conducted numerically using air-injection technique in a model chamber, where air is supplied to oxidizer and fuel manifolds of the model five-element injector head. A sample F(fuel)-O(oxidizer)-O-F impinging-jet injector is adopted. In this technique, we can simulate mixing process of streams flowing through oxidizer and fuel orifices under cold-flow condition without chemical reaction. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions. From numerical data, unstable regions can be identified and they are compared with those from air-injection acoustic and hot-fire tests. The present stability boundaries are in a good agreement with experimental results. The proposed numerical method can be applied cost-effectively to stability rating of jet injectors when mixing of fuel and oxidizer jets is the dominant process in instability triggering.
Particle Dispersion and Fine Scale Eddies in Wall Turbulence
Kang, Shin-Jeong ; Tanahashi, Mamoru ; Miyauchi, Toshio ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1101~1106
DOI : 10.3795/KSME-B.2006.30.11.1101
To investigate a relation between fine scale eddies and particle dispersion in a near-wall turbulence, direct numerical simulations of turbulent channel flow laden particle are performed for
=180. The motions of 0,8 million particles are calculated for several particle response times (
) which is the particle response time based on stokes’ friction law. The number density of particles has a tendency to increase with approaching the near-wall regions (
<20) except for cases of very small and large particle response times (i.e.
=0.02 and 15). Near the wall, the behavior and distribution of particles are deeply associated with the fine scale eddies, and are dependent on particle response times and a distance from the wall. The Stokes number that causes preferential distribution in turbulence is changed by a distance from the wall. The influential Stokes number based on the Burgers' vortex model is derived by using the time scale of the fine scale eddies. The influential Stokes number is also dependent on a distance from the wall and shows large value in the buffer layer.
Numerical Study on Bubble Growth and Droplet Ejection in a Bubble Inkjet Printer
Suh, Young-Ho ; Son, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1107~1116
DOI : 10.3795/KSME-B.2006.30.11.1107
The droplet ejection process driven by an evaporating bubble in a thermal inkjet printhead is investigated by numerically solving the conservation equations for mass, momentum and energy. The phase interfaces are tracked by a level set method which is modified to include the effect of phase change at the interface and extended for multiphase flows with irregular solid boundaries. The compressibility effect of a bubble is also included in the analysis to appropriately describe the bubble expansion behaviour associated with the high pressure caused by bubble nucleation. The whole process of bubble growth and collapse as well as droplet ejection during thermal inkjet printing is simulated without employing a simplified semi-empirical bubble growth model. Based on the numerical results, the jet breaking and droplet formation behaviour is observed to depend strongly on the bubble growth and collapse pattern. Also, the effects of liquid viscosity, surface tension and nozzle geometry are quantified from the calculated bubble growth rate and ink droplet ejection distance.
Development of the 1kW Class Regenerative Fuel Cell for Ground Simulator of Regeneration Electric Power System
Kim, Hyung-Mo ; Yang, Cheol-Nam ; Hong, Byung-Sun ; Park, Young-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1117~1122
DOI : 10.3795/KSME-B.2006.30.11.1117
The PEM type regenerative fuel cell(RFC) for the ground simulator of the regeneration electric power system has been designed, manufactured, and tested. In this paper, the designing and manufacturing procedures of the RFC were presented. Also, the performance test results were showed briefly. The RFC consists of PEM type stack, humidifier, pressure and flow control valve, storage tanks, pump and controller. The performance tests were carried out with stack and system performance tests. The performance targets are more than 50% stack efficiency, 1.5kW stack power, less 400W parasitic power in design condition. Most of the performances required are satisfied.
Study on n-Butane Autothermal Reforming for Portable Fuel Cell
Bae, Gyu-Jong ; Kang, In-Young ; Lim, Sung-Kwang ; Bae, Joong-Myeon ; Kim, Ju-Yong ; Lee, Chan-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1123~1130
DOI : 10.3795/KSME-B.2006.30.11.1123
This study discusses about research efforts of hydrogen generation from hydrocarbon(e.g., diesel, gasoline, natural gas, and LPG), especially, butane reforming by using Autothermal Reforming Reaction (ATR) technology. Several catalysts were selected for butane ATR. Thermodynamic reactor conditions (temperature,
/C, S/C) are varied and reforming characteristics of 2 catalysts (Pt and Rh on ceramic supports) and 1 commercial catalyst (FCR-HC35) have been examined. To understand reaction behaviors in an ATR reactor comprehensively, temperature profiles of reactor were observed. By mass transfer limitation, fuel conversion decreases when GHSV increases. Significant temperature variation along the reactor was observed and it was mainly due reaction kinetics difference between exothermic oxidation and endothermic reforming reaction.
Aerodynamic Shape Design of a Partial Admission Turbine Using CFD
Lee, Eun-Seok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 30, issue 11, 2006, Pages 1131~1138
DOI : 10.3795/KSME-B.2006.30.11.1131
Aerodynamic shape design of a partial admission turbine using CFD has been performed. Two step approaches are adopted in this study. Firstly, two-dimensional blade shape is optimized using CFD and genetic algorithm. Initially, the turbine cascade shape is represented by four design parameters. By controlling the design parameters as variables, the non-gradient search is analyzed for obtaining the maximum efficiency. The final two-dimensional blade proved to have a more blade power than the initial blade. Secondly, the three-dimensional CFD analysis including the nozzle, rotor and stator has been conducted. To avoid a heavy computational load due to an unsteady calculation, the frozen rotor method is implemented in steady calculation. The frozen rotor method can detect a variation of the flow-field dependent upon the blade's circumferential position relative to the nozzle. It gives a better idea of wake loss mechanism starting from the lip of the nozzle than the mixing plane concept. Finally, the combination of two and three dimensional design method of the partial admission turbine in this study has proven to be a robust tool in development phase.