Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 34, Issue 12 - Dec 2010
Volume 34, Issue 11 - Nov 2010
Volume 34, Issue 10 - Oct 2010
Volume 34, Issue 9 - Sep 2010
Volume 34, Issue 8 - Aug 2010
Volume 34, Issue 7 - Jul 2010
Volume 34, Issue 6 - Jun 2010
Volume 34, Issue 5 - May 2010
Volume 34, Issue 4 - Apr 2010
Volume 34, Issue 3 - Mar 2010
Volume 34, Issue 2 - Feb 2010
Volume 34, Issue 1 - Jan 2010
Selecting the target year
Computational Fluid Dynamics Study on Uniform Cooling of Polymer Electrolyte Membrane Fuel Cells by Parallel Multi-pass Serpentine Flow Fields
Yu, Seung-Ho ; Baek, Seung-Man ; Nam, Jin-Hyun ; Kim, Charn-Jung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 885~891
DOI : 10.3795/KSME-B.2010.34.10.885
Thermal management is important for enhancing the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs) and is taken into account in the design of PEMFCs. In general, cooling pates with circulating liquid coolant (water) are inserted between several unit cells to exhaust the reaction heat from PEMFCs. In this study, computational fluid dynamics (CFD) simulations were performed to characterize the uniform cooling performance of parallel multipass serpentine flow fields (MPSFFs) that were used as coolant flow channels in PEMFCs. The cooling performances of conventional serpentine and parallel flow fields were also evaluated for the purpose of comparison. The CFD results showed that the use of parallel MPSFFs can help reduce the temperature nonuniformity, and thus, can favorably enhance the performance and durability of PEMFCs.
Atherogenic Risk Stratification According to Changes in the Geometrical Shape of the Coronary Artery
Suh, Sang-Ho ; Park, Jun-Gil ; Roh, Hyung-Woon ; Lee, Byung-Kwon ; Kwon, Hyuck-Moon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 893~899
DOI : 10.3795/KSME-B.2010.34.10.893
A previous study showed that hemodynamics is correlated with stenosis in the coronary artery. The flow characteristics and the distributions of the hemodynamic wall parameters in the coronary artery are investigated under physiological flow condition. The present study also aims to establish the mechanism of the generation of atherosclerosis by analyzing the hemodynamic variables in the coronary artery where atherosclerosis frequently occurs. The stenosis phenomena due to atherosclerosis are related to not only the biochemical reaction between blood and blood vessels but also the hemodynamic factors sush as flow separation and oscillatory wall shear stress. As the bifurcated angle increases, the size of the recirculation area that appears in the cross section increases and disturbed flow is observed in this area. We speculate that this area is the starting point of atherosclerosis in the coronary artery.
A Numerical Study on the Effect of Mountainous Terrain and Turbine Arrangement on the Performance of Wind Power Generation
Lee, Myung-Sung ; Lee, Seung-Ho ; Hur, Nahm-Keon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 901~906
DOI : 10.3795/KSME-B.2010.34.10.901
A three-dimensional flow simulation was performed to investigate the flow field in a wind farm on a complex terrain. The present study aims to examine the effects of mountainous terrain and turbine arrangement on the performance of wind power generation. A total of 49 wind turbines was modeled in the computational domain; detailed blade shape of the turbines was considered. Frozen rotor method was used to simulate the rotating operation. The torque acting on the turbine blades was calculated to evaluate the performance of the wind turbines. The numerical results showed details of the flow structure in the wind farm including the velocity deficit in the separated flow regions; this velocity deficit was due to the topographical effect. The effect of the wake induced by the upstream turbine on the performance of the downstream wind turbine could also be observed from the results. The methodology of the present study can be used for selecting future wind-farm sites and wind-turbine locations in a selected site to ensure maximum power generation.
Enhancement of MCFC System Performance by Adding Bottoming Cycles
Ji, Seung-Won ; Park, Sung-Ku ; Kim, Tong-Seop ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 907~916
DOI : 10.3795/KSME-B.2010.34.10.907
Integration of various bottoming cycles such as the gas turbine (GT) cycle, organic Rankine cycle, and oxy-fuel combustion cycle with an molten carbonate fuel cell (MCFC) power-generation system was analyzed, and the performance of the power-generation system in the three cases were compared. Parametric analysis of the three different integrated systems was carried out under conditions corresponding to the practical use and operation of MCFC, and the optimal design condition for each system was derived. The MCFC/oxy-combustion system exhibited the greatest power upgrade from the MCFC-only system, while the MCFC/GT system showed the greatest efficiency enhancement.
Turbulent Statistics of the Turbulent Boundary Layer over a Cube-Roughened Wall
Lee, Jae-Hwa ; Sung, Hyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 917~923
DOI : 10.3795/KSME-B.2010.34.10.917
Direct numerical simulation (DNS) of a spatially developing turbulent boundary layer (TBL) with regularly arrayed cubical roughness elements was performed to investigate the effects of three-dimensional (3D) surface elements. The staggered cubes downstream were periodically arranged in the streamwise and spanwise directions with pitches of
are the streamwise and spanwise spacings of the cubes; the roughness height (k) was k=
is the momentum thickness at the inlet. Spatially developing characteristics over the 3D cubical roughness were compared with the data obtained from the DNS over the two-dimensional (2D) rod roughened wall and smooth wall. Introduction of the cubical roughness on the TBL affected the turbulent Reynolds stresses not only in the roughness sublayer but also in the outer layer; and these effects are consistent with those observed over the 2D rough wall.
Numerical Study on Turbulent Flow Inside a Channel with an Extended Chamber
Lee, Young-Tae ; Lim, Hee-Chang ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 925~931
DOI : 10.3795/KSME-B.2010.34.10.925
The paper describes a Large Eddy Simulation (LES) study of turbulent flow around a cavity. A series of three-dimensional cavities placed in a turbulent boundary layer are simulated at a Reynolds number of
by considering U and h, which represent the velocity at the top and the depth of the cavity, respectively. In order to obtain the appropriate solution for the filtered Navier-Stokes equation for incompressible flow, the computational mesh forms dense close to the wall of the cavity but relatively coarse away from the wall; this helps reduce computation cost and ensure rapid convergence. The Boussinesq hypothesis is employed in the subgrid-scale turbulence model. In order to determine the subgrid-scale turbulent viscosity, the Smagorinsky-Lilly SGS model is applied and the CFL number for time marching is set as 1.0. The results show the flow variations inside cavities of different sizes and shapes.
Experimental Study of Discharge Coefficient and Cavitation for Different Nozzle Geometries
Kim, Sung-Ryoul ; Ku, Kun-Woo ; Hong, Jung-Goo ; Lee, Choong-Won ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 933~939
DOI : 10.3795/KSME-B.2010.34.10.933
The purpose of this study is to investigate the generation and development of cavitation in circular and elliptical nozzles. In order to investigate the influence of cavitation, the experiment was conducted with a set of elliptical nozzles that had the same cross-sectional area, different orifice aspect ratios (a/b). Each nozzle was made of acrylic so that visualization was possible. With the injection pressure, the internal flow of the nozzle was classified into the no-cavitation, cavitation, and hydraulic-flip regions. Regardless of the nozzle geometry, with the injection pressure, the flow rate in the no-cavitation and cavitation regions increased and the discharge coefficient decreased. However, the flow rate was constant in the hydraulic-flip region. In the elliptical nozzles, the generation and development of cavitation occurred at higher cavitation number than that in the case of a circular nozzle.
Effects of Soybean Biodiesel Fuel on Exhaust Emissions in Compression Ignition Combustion
Han, Man-Bae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 941~946
DOI : 10.3795/KSME-B.2010.34.10.941
This study aims to investigate the effects of soybean biodiesel fuel on exhaust emissions with regards to two combustion modes: conventional combustion(existence of PM-NOx trade-off behavior) and low temperature combustion(LTC) in a 1.7 L common rail direct injection diesel engine. As compared to conventional combustion, LTC was achieved by adopting a heavier exhaust gas recirculation and strategic injection parameter optimization. Two sets of fuels, i.e. ultra low sulfur diesel(ULSD) and 20% volumetric blends of soybean biodiesel with ULSD(B20) were used. Regardless of the fuel type, in LTC the simultaneous reduction of PM and NOx was observed and both levels were significantly lower than in case of conventional combustion. Under the given engine operating condition in the case of conventional combustion, B20 produced less PM and more NOx than ULSD. In the case of LTC combustion, B20 produced more PM and NOx than ULSD.
Study on the Convergency Improvement Method for the Saturation-Property Calculation of Multi-Component Hydrocarbon Systems
Shin, Chang-Hoon ; An, Seung-Hee ; Lee, Jeong-Hwan ; Sung, Won-Mo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 10, 2010, Pages 947~955
DOI : 10.3795/KSME-B.2010.34.10.947
Most oil and gas reservoirs, which have some light hydrocarbon components, show sensitive phase behavior in response to changes in the composition of the internal fluid. When evaluating and developing plans for oil and gas fields, flash calculation, PVT analysis, and saturation-property calculation are necessary for analyzing reservoir characteristics and pipeline flows. In general, the determination of saturation properties such as dew point and bubble point is considered a difficult task because of the poor convergence of the calculation methods. In this study, several new initial-value-guessing methods and root-finding methods are proposed; parametric analysis were carried out to verify the improvement in convergence. Finally, these new ideas and methods were successfully applied to the new GUI based multi-phase behavior simulator.