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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 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
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Flow Characteristics of Driven Nozzle Position Change in the Connected Injection Pump
Sohn, Hyun-Chull ; Park, Gil-Moon ; Go, Hyun-Sun ; Lee, Haeng-Nam ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 215~224
DOI : 10.3795/KSME-B.2009.33.4.215
Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.
Three-Dimensional Numerical Analysis on Recirculation Generated by Obstacles Around a Cooling Tower
Choi, Young-Ki ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 225~234
DOI : 10.3795/KSME-B.2009.33.4.225
The present study has been preformed to investigate the effect of obstacles around a cooling tower with air-guide to prevent recirculation. The external region as well as the cooling tower are included in the computational domain to analyze the flow phenomena around a cooling tower accurately. Three-dimensional analysis is performed using the finite volume method with non-orthogonal and unstructured grid system. The standard turbulence model is used to consider the turbulence effect. In order to investigate the recirculation phenomena, flow and temperature fields are calculated with the distance between cooling tower and obstacle, the allocated geometrical type and the air-guide. The moisture fraction rates decrease with increment of the distance between cooling tower and obstacle. The effect of air-guide to reduce the mean recirculation rate is obviously observed.
Heat Transfer Characteristics on Toroidal Convection Loop with Nanofluids
Jang, Ju-Chan ; Rhi, Seok-Ho ; Lee, Chung-Gu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 235~241
DOI : 10.3795/KSME-B.2009.33.4.235
Experimental studies on single-phase toroidal circulation loop(thermosyphon) have been performed in the present study with Ag-nanofluids as a working fluids. The present paper deals with an experimental study on the heat transfer behavior of single-phase toroidal loop. Toroidal loop charged with nanofluid has been constructed and a number of tests have been carried out. Different geometric parameter, e.g., orientation has been investigated. The tests were conducted employing two fluids: distilled water and Ag-nanofluid of various volume concentrations. The experiments at Rayleigh number from
showed a systematic and slight deterioration in natural convective heat transfer. It was observed that the deterioration due to the particle concentration was in the range of 5-10%. At a given particle concentration of 0.05%, abrupt decrease in the Nusselt number and the Raleigh number was observed. The present study with toroidal loop shows that the application of nanofluids for heat transfer intensification should not be decided only by the effective thermal conductivity with increasing particle concentration.
Preconditioning Method of a Finite Element Combined Formulation for Fluid-Structure Interaction
Choi, Hyoung-Gwon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 242~247
DOI : 10.3795/KSME-B.2009.33.4.242
AILU type preconditioners for a two-dimensional combined P2P1 finite element formulation of the interaction of rigid cylinder with incompressible fluid flow have been devised and tested by solving fluid-structure interaction (FSI) problems. The FSI code simulating the interaction of a rigid cylinder with an unsteady flow is based on P2P1 mixed finite element formulation coupled with combined formulation. Four different preconditioners were devised for the two-dimensional combined P2P1 finite element formulation extending the idea of Nam et al., which was proposed for the preconditioning of a P2P1 mixed finite element formulation of the incompressible Navier-Stokes equations. It was found that PC-III or PC-IV among them perform well with respect to computational memory and convergence rate for some bench-mark problems.
Effect of the Boost Pressure on Thermal Stratification on HCCI Engine Using Multi-Zone Modeling
Kwon, O-Seok ; Lim, Ock-Taeck ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 248~254
DOI : 10.3795/KSME-B.2009.33.4.248
The HCCI engine is a next generation engine, with high efficiency and low emissions. The engine may be an alternative to SI and DI engines; however, a pressure rise rate is a major limitation for high load range and power reduction. Recently, we were able to reduce the pressure rise rate using thermal stratification. Nevertheless, this was insufficient to produce high power. In this study, the reduction of the pressure rise rate using thermal stratification was confirmed and the HCCI engine power was increased using the boost pressure. The rate and engine power were produced by CHEMKIN and modified SENKIN. As a result of increasing the boost pressure, a higher IMEP was attained while the pressure rise rate increased only slightly in the HCCI with thermal stratification.
Study on the Fueling Economic Feasibility of Plug-in Hybrid Electric Vehicle
Roh, Chul-Woo ; Kim, Min-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 255~263
DOI : 10.3795/KSME-B.2009.33.4.255
The most concerning issue of these days is the energy crisis caused by increasing threat of dependence on imported oil and volatile market trend. Under these circumstances, the PHEV(plug-in hybrid electric vehicle) is drawing attention for the next generation's car which could give a chance to decrease the dependence on imported oil and reduce the environmental impact of vehicle. The fueling cost of PHEV, one of the core factor of decision about buying car, should be calculated in the circumstances of Korea to make sure that PHEV has competitive power in real market. The fuel cost saving of PHEV versus CV(conventional vehicle) is simulated and discussed in the condition of increasing gasoline cost, electricity rate, and city-gas rate. In conclusion, the PHEV60-FS shows the best economic feasibility when gasoline price goes up. The PHEV20 has the most stable economic feasibility as electricity rate increases. The fuel cell cogeneration system for RPG could be an alternative for charger of PHEV in the near future.
Behavioral Characteristics of the Non-Premixed Methane-Air Flame Oppositely Injected in a Narrow Channel
Yun, Young-Min ; Lee, Min-Jung ; Cho, Sang-Moon ; Kim, Nam-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 264~271
DOI : 10.3795/KSME-B.2009.33.4.264
Characteristics of a counter flowing diffusion flame, which is formulated by an oppositely-injected methane-jet flow in a narrow channel of a uniform air flow. The location of the flame fronts and the flame lengths were compared by changing the flow rates of fuel. To distinguish the effects of the narrow channel on the diffusion flame, a numerical simulation for an ideal two-dimensional flame was conducted. Overall trends of the flame behavior were similar in both numerical and experimental results. With the increase of the ratio of jet velocity to air velocity flame front moved farther upstream. It is thought that the flow re-direction in the channel suppresses fuel momentum more significantly due to the higher temperature and increased viscosity of burned gas. Actual flames in a narrow channel suffer heat loss to the ambient and it has finite length of diffusion flame in contrast to the numerical results of infinite flame length. Thus a convective heat loss was additionally employed in numerical simulation and closer results were obtained. These results can be used as basic data in development of a small combustor of a nonpremixed flame.
Reaction Characteristics of LPG Fuel and Rubber Parts of Fuel Supply System in Liquid Phase LPG Injection (LPLi) System
Kim, Chang-Up ; Park, Cheol-Woong ; Kang, Kern-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 272~277
DOI : 10.3795/KSME-B.2009.33.4.272
The liquid phase LPG injection (LPLi) system (the 3rd generation technology) has been considered as one of the most promising fuel supply systems for LPG vehicles. To investigate the reaction characteristics of LPG with rubber parts in LPLi system, various rubbers were tested. The results showed that the amount of residue from the cover rubber of a fuel pump was increased about 10 times after testing. Furthermore, the amount of sulfur and nitrogen species which are considered as main sources of deposit formation in LPLi fuel injectors were also found to be higher than those in original LPG fuel. In addition, these residues made the core parts of LPLi injector such as needle and nozzle, partially worn, which eventually causes leakage in LPLi injectors.
Study on the Power-Grid Impact and Optimal Charging Control Strategy with PHEV Market Penetration
Roh, Chul-Woo ; Kim, Min-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 278~287
DOI : 10.3795/KSME-B.2009.33.4.278
Plug-in hybrid electric vehicle (PHEV) with capability of being recharged from the power-grid will reduce oil consumption. Also, the PHEV will affect the utility operations by adding additional electricity demand for charging. In this research, the power-grid impact by demand of PHEV charging is presented and the optimal charging control strategy for utility operators is proposed with simulated data. The penetration of PHEV is assumed to be 50% in the circumstances of Korean passenger car market and Korean power-grid market limitedly. To obtain smooth load shape and utilize the surplus electricity in power-grid at midnight and dawn, the peak of charging demand should be controlled to be located before 4:00 a.m., and the time slot which can supply the electricity power to PHEV should be allowed between 1:00 a.m.
A Study on the Bypass Flow Penetrating Through a Gas Diffusion Layer in a PEM Fuel Cell with Serpentine Flow Channels
Cho, Choong-Won ; Ahn, Eun-Jin ; Lee, Seung-Bo ; Yoon, Young-Gi ; Lee, Won-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 4, 2009, Pages 288~297
DOI : 10.3795/KSME-B.2009.33.4.288
A serpentine channel geometry often used in a fuel cell has a strong pressure gradient between adjacent channels in specific regions. The pressure gradient helps some amount of reactant gas penetrate through a gas diffusion layer(GDL). As a result, the overall serpentine flow structure is slightly different from the intention of a designer. The purpose of this paper is to examine the effect of serpentine flow structure on current density distribution. By using a commercial code, STAR-CD, a numerical simulation is performed to analyze the fuel cell with high aspect ratio of active area. To increase the accuracy of the numerical simulation, GDL permeabilities are measured with various compressive forces. Three-dimensional flow field and current density distribution are calculated. For the verification of the numerical simulation results, water condensation process in the cathode channel is observed through a transparent bipolar plate. The result of this study shows that the region of relatively low current density corresponds that of dropwise condensation in cathode channels.