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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 33, Issue 12 - Dec 2009
Volume 33, Issue 11 - Nov 2009
Volume 33, Issue 10 - Oct 2009
Volume 33, Issue 9 - Sep 2009
Volume 33, Issue 8 - Aug 2009
Volume 33, Issue 7 - Jul 2009
Volume 33, Issue 6 - Jun 2009
Volume 33, Issue 5 - May 2009
Volume 33, Issue 4 - Apr 2009
Volume 33, Issue 3 - Mar 2009
Volume 33, Issue 2 - Feb 2009
Volume 33, Issue 1 - Jan 2009
Selecting the target year
Three-dimensional Laminar Flow Past a Rotating Cylinder
Lee, Yong-Suk ; Yoon, Hyun-Sik ; Doo, Jeong-Hoon ; Ha, Man-Yeong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 827~833
DOI : 10.3795/KSME-B.2009.33.11.827
The present study numerically investigates three-dimensional laminar flow past a rotating circular cylinder placed in a uniform stream. For the purpose of a careful analysis of the modification of flow by the effect of the rotation on the flow, numerical simulations are performed at a various range of rotational coefficients (
) at one Reynolds number of 300. As
increases, flow becomes stabilized and finally a steady state beyond the critical rotational coefficient. The 3D (three dimensional) wake mode of the stationary cylinder defined at this Reynolds number has been disorganized according to
, which were observed by the visualization of 3D vortical structures. The variation of the Strouhal number is very weak when the wake pattern is changed according to the rotational coefficient. As
increases, the lift increases, whereas the drag decreases.
Numerical Analysis of the Gas Flow Distribution Characteristics in the Anode Flow Channel of Molten Carbonate Fuel Cell (MCFC)
Cho, Jun-Hyun ; Ha, Tae-Hun ; Kim, Han-Sang ; Min, Kyoung-Doug ; Park, Jong-Hoon ; Chang, In-Gab ; Lee, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 834~839
DOI : 10.3795/KSME-B.2009.33.11.834
A three-dimensional computational fluid dynamics (CFD) analysis is performed to investigate flow characteristics in the anode channels and manifold of the internal reforming type molten carbonate fuel cell (MCFC). Considering the computational difficulties associated with the size and geometric complexity of the MCFC system, the polyhedral meshes that can reduce mesh connectivity problems at the intersection of the channel and the manifold are adopted and chemical reactions inside the MCFC system are not included. Through this study, the gas flow rate uniformity of the anode channels is mainly analyzed to provide basic insights into improved design parameters for anode flow channel design. Results indicate that the uniformity in flow-rate is in the range of
1% between the anode channels. Also, the mal-distributed inlet flow-rate conditions and the change in the size of the manifold depth have no significant effect on the flow-rate uniformity of the anode channels.
Experimental Investigation of CHF Enhancement on the Modified Surface Under Pool Boiling
Kang, Soon-Ho ; Ahn, Ho-Seon ; Jo, Hang-Jin ; Kim, Moo-Hwan ; Kim, Hyung-Mo ; Kim, Joon-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 840~848
DOI : 10.3795/KSME-B.2009.33.11.840
In the boiling heat transfer mechanism, CHF(critical heat flux) is the significantly important parameter of the system. So, many researchers have been struggling to enhance the CHF of the system in enormous methods. Recently, there were lots of researches about enormous CHF enhancement with the nanofluids. In that, the pool boiling CHF in nanofluids has the significantly increased value compared to that in pure water because of the deposition of the nanoparticle on the heater surface in the nanofluids. The aim of this study is the comparison of the effect of the nanoparticle deposited surface and the modified surface which has the similar morphology and made by MEMS fabrication. The nanoparticle deposited surface has the complex structures in nano-micro scale. Therefore, we fabricated the surfaces which has the similar wettability and coated with the micro size post and nano structure. The experiment is performed in 3 cases : the bare surface with 0.002% water-ZnO nanofluids, the nanoparticle deposited surface with pure water and the new fabricated surface with pure water. The contact angle, a representative parameter of the wettability, of the all 3 cases has the similar value about 0 and the SEM(scanning electron microscope) images of the surfaces show the complex nano-micro structure. From the pool boiling experiment of the each case, the nanoparticle deposited surface with pure water and the fabricated surface with pure water has the almost same CHF value. In other words, the CHF enhancement of the nanoparticle deposited surface is the surface effect. It also shows that the new fabricated surface follows the nanoparticle deposited surface well.
The Study on Flame Structure and NOx Emissions by Swirl Numbers and Fuel-Air Mixing Length in a Dump Combustor Gas Turbine
Choi, Do-Wook ; Kim, Gyu-Bo ; Jeon, Chung-Hwan ; Song, Ju-Hun ; Chang, Young-June ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 849~857
DOI : 10.3795/KSME-B.2009.33.11.849
The experimental study was performed to investigate the effects of partial premixing, varying the equivalence ratio, mixing degree, swirl intensity, mixing length on the characteristics of flame structure and NOx emission. Experiments were conducted in a dump combustor at 1 bar using methane as fuel. Inlet air temperature was 570K. OH chemiluminescence images were acquired with an ICCD camera. As a result of the experimental investigation of characteristics of flame and NOx emission in partial premixed combustor, we can conclude the results as below. With the increase of swirl number, The flame length decreases and the flame width increases and it helps flame stabilization. It means that lean flammability limit is extended. With the increase of mixing of fuel-air length ratio, Flame goes to be stabilized and NOx emission and
intensity decrease. Through the comparison of preceding results, It is possible that the exhausted NOx emission from a gas turbine combustor will be able to predict through the
A Numerical Study on the Effects of SOFA on NOx Emission Reduction in 500MW Class Sub-bituminous Coal-Fired Boiler
Kang, Ki-Tae ; Song, Ju-Hun ; Yoon, Min-Ji ; Lee, Byoung-Hwa ; Kim, Seung-Mo ; Chang, Young-June ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 858~868
DOI : 10.3795/KSME-B.2009.33.11.858
A numerical investigation has been carried out about the performance of a 500MW class tangentially coal-fired boiler, focusing on the optimization of separated overfire air (SOFA) position to reduce NOx emission. For this purpose, a comprehensive combination of NOx chemistry models has been employed in the numerical simulation of a particle-laden flow along with solid fuel combustion and heat and mass transfer. A reasonable agreement has been shown in baseline cases for predicted operational parameters compared with experimental data measured in the boiler. A further SOFA calculation has been made to obtain optimum elevation and position of SOFA port. Additionally, clarifying on the effect of SOFA on NOx emission has been carried out in the coal-fired boiler. As a result, this paper is valuable to provide an information about the optimum position of SOFA and the mechanism by which the SOFA would affect NOx emission.
Propane Reforming in Gliding Arc Plasma Reformer for SynGas Generation
Yang, Yoon-Cheol ; Chun, Young-Nam ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 869~875
DOI : 10.3795/KSME-B.2009.33.11.869
The purpose of this paper is to investigate the optimal condition of the syngas production by reforming of propane using Gliding arc plasma reformer. The gliding arc plasma reformer in 3 phases has been newly designed and developed with a quick starting and fast response time. It can be applicable to the various types of fuels (Hydrocarbons
), and it has a high conversion rate of fuels and high production of hydrogen. The parametric screening studies were carried out according to the changes of a steam feed amount i.e., steam/carbon ratio, total gas flow rate and input electric power. The optimum operating conditions were S/C ratio 2.8, total gas flow rate of 14 L/min and input electric power of 2.4 kW. The result of optimum operating conditions showed the 55 %
, 14 % CO, 15 %
, 10 %
and 4 %
selectivity were 90 %, 42 %, 15 %, respectively. The energy efficiency and specific energy requirements were 37 % and 334 kJ/mol respectively.
Determination of Char Oxidation Rates with Different Analytical Methods
Lee, Byoung-Hwa ; Song, Ju-Hun ; Kang, Ki-Tae ; Chang, Young-June ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 876~885
DOI : 10.3795/KSME-B.2009.33.11.876
Char oxidation experiments were performed with a sub-bituminous roto-middle coal in the Drop Tube Furnace (DTF) at atmospheric pressure condition. While temperatures varied between 900, 1100, 1400
, particle size, mass, particle temperature, and CO/
concentration were obtained to be used for kinetic analysis of the char oxidation. This study addresses several different methods to analyze the char consumption rate, which are classified as energy balance method, ash-traced mass method, flue-gas based method, and particle size based method. The char consumption rate obtained with such methods was compared with the results of Monson et al.
While there are some differences between them because of differences in experimental apparatus and parameters to be measured, the kinetic results seems to be reasonable enough to be incorporated in a numerical modeling of coal combustion.
Study on Flow Analysis in Glass Panel Vacuum Lift System
Kim, Dong-Kyun ; Yoon, Cheon-Seog ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 886~893
DOI : 10.3795/KSME-B.2009.33.11.886
To develop glass panel vacuum lift system for the post process in module line of FPD(Flat panel display) such as LCD and PDP, new vacuum adsorption parts of this system are proposed. These parts are composed of variable geometry configurations utilizing ceramic porous medium for variable size of glass panels. In order to design this device, detail understanding of flow phenomena in the flow path of vacuum adsorption system is essential. Thus, CFD analysis and designs are performed for several configurations in terms of pressure drop and balancing force at the adsorption side. From the result, new configuration is recommended for optimum design and manufacturing purpose.
A Method to Define Steady-State Curves for Variable-Speed Variable-Pitch Wind Turbine
Lim, Chae-Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 894~899
DOI : 10.3795/KSME-B.2009.33.11.894
Aerodynamic power and torque of wind turbine are highly nonlinear and its operation mode depends on control strategies. Therefore, it is essential to define steady-state curves for the purpose of control and operation of wind turbine system. The steady-state curves of wind turbine can be defined by determining its operating points. In this paper, an algorithm to determine operating points of variable-speed variable-pitch wind turbine is presented on the basis of pitch-to-feather control strategy. And this algorithm is applied to obtain steady-state curves for an 1.5MW wind turbine.
Numerical Study of Radial Temperature Gradient Effect on Taylor Vortices
Kang, Chang-Woo ; Yang, Kyung-Soo ; Yoon, Dong-Hyeog ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 900~908
DOI : 10.3795/KSME-B.2009.33.11.900
Numerical simulation has been carried out to investigate the influence of radial temperature gradient on the Taylor Vortex flow. Varying the Grashof number, we study the detailed flow and temperature fields. The current numerical results show good agreement with the experimental results currently available. It turns out that wavy spiral vortices are generated by increasing temperature gradient. We classify flow patterns for various Grashof numbers based on the characteristics of flow fields and spiral vortices. The correlation between Grashof number with wave number shows that the spiral angle and size of Taylor vortices increase with increasing temperature gradient. Temperature gradient does not have a great influence on the heat transfer rate of the cylinder surfaces.
A Study of NPSH Required Performance Improvement for a Industrial Vertical Pump
Chung, Kyung-Nam ; Park, Jong-Hwoo ; Kim, Yong-Kyun ; Kim, Hae-Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 909~915
DOI : 10.3795/KSME-B.2009.33.11.909
In this paper, a study of performance improvement for a centrifugal vertical pump having specific speed of 330 is introduced. The existing model has high efficiency but needs better NPSH required performance. Such that new pump model is designed to obtain larger suction specific speed. 6 design parameters considered to affect pump performance are selected for impeller design. Key design parameters are investigated using by design of experiments and CFD, and impeller inlet diameter is increased to get better suction performance. The amount of inlet diameter increase is determined by using cavitation analysis. The results show that new design model has higher efficiency and better NPSH required performance than the existing model.
Stabilization Characteristics of DME-Air Diffusion Flames Depending on the Configuration of the Fuel-Air Tubes in Half Closed Combustion Spaces
Kim, Go-Tae ; Kim, Nam-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 916~923
DOI : 10.3795/KSME-B.2009.33.11.916
The effects of configuration of fuel and air tubes on the flame stabilization were experimentally investigated in half-closed combustors. Flame behaviors and stabilities of methane, propane, and DME flames were compared by changing tube diameters and the locations of the fuel and air tubes. It was found that flammability limits are significantly affected by the outlet boundary condition, which disturbs compositions of burned and unburned mixtures near the flame base. And it was found that there exist critical inner tube heights, over which flame stability is determined only by the fuel flow rate. Conclusively, flame stabilization is governed by the flame propagation velocity in an ordinary mixing flow and the non-uniform mixture concentration in the combustion space which is affected by flow recirculation and the combustor configuration. The compositions of
and CO were compared to know basic characteristics of methane, propane, and DME flames.
Analysis of Two-Dimensional Turbulent Flow around the Horn-type Rudder
Jeong, Nam-Gyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 11, 2009, Pages 924~931
DOI : 10.3795/KSME-B.2009.33.11.924
The two-dimensional turbulent flow around the horn-type rudder has been examined in the present study by using the commercial code FLUENT. The standard
model is used as a closure relationship. The geometry of horn rudder is based on the NACA 0020 airfoil. The simulations for various angle attack (
) and yaw angle(
) are carried out. The effect of Reynolds number is also investigated in this study. The cavitation is more possible when the yaw angle is
and it is more serious as Reynolds number increases.