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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 38, Issue 12 - Dec 2014
Volume 38, Issue 11 - Nov 2014
Volume 38, Issue 10 - Oct 2014
Volume 38, Issue 9 - Sep 2014
Volume 38, Issue 8 - Aug 2014
Volume 38, Issue 7 - Jul 2014
Volume 38, Issue 6 - Jun 2014
Volume 38, Issue 5 - May 2014
Volume 38, Issue 4 - Apr 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
Selecting the target year
Improved Thermoacoustic Model Considering Heat Release Distribution
Kim, Daesik ; Kim, Kyu Tae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 443~449
DOI : 10.3795/KSME-B.2014.38.6.443
Thermoacoustic (TA) models have been widely used to predict combustion instability characteristics in a gas turbine lean premixed combustor. However, these techniques have shown some limitations in improving the model accuracy related to an over-simplification of the combustion system and flame geometry. Efforts were made in the current study to improve the limitations of the TA models. One strategy was to modify the actual flame location in the model, and another was to consider the heat release distribution through the flames. The modified TA model results show better accuracy in predicting the growth rate of instabilities compared with the previous results.
Numerical Investigation of Exhaust Gas Recirculation Effect under Boost Pressure Condition on Homogeneous Charge Compression Autoignition
Oh, Chung Hwan ; Jamsran, Narankhuu ; Lim, Ock Tack ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 451~464
DOI : 10.3795/KSME-B.2014.38.6.451
This study used numerical methods to investigates investigate the exhaust gas recirculation (EGR) effect under the condition of boost pressure condition on a homogeneous charge compression ignition (HCCI) combustion engine using numerical methods. The detailed chemical-kinetic mechanisms and thermodynamic parameters for n-heptane, iso-octane, and PRF50 from the Lawrence Livermore National Laboratory (LLNL) are were used for this study. The combustion phase affects the efficiency and power. To exclude these effects, this study decided to maintain a 50 burn point (CA50) at 5 CA after top dead center aTDC. The results showed that the EGR increased, but the low temperature heat release (LTHR), negative temperature coefficient (NTC), and high temperature heat release (HTHR) were weakened due by theto effect of the O2 reduction. The combined EGR and boost pressure enhanced the autoignition reactivity, Hhence, the LTHR, NTC, and HTHR were enhanced, and the heat-release rate was increased. also In addition, EGR decraeased the indicated mean effective pressure (IMEP), but the combined EGR and boost pressure increased the IMEP. As a results, combining the ed EGR and boost pressure was effective to at increase increasing the IMEP and maintaining the a low PRR.
Experimental Study on Heat Flux Partitioning in Subcooled Nucleate Boiling on Vertical Wall
Song, Junkyu ; Park, Junseok ; Jung, Satbyoul ; Kim, Hyungdae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 465~474
DOI : 10.3795/KSME-B.2014.38.6.465
To validate the accuracy of the boiling heat flux partitioning model, an experiment was performed to investigate how the wall heat flux is divided into the three heat transfer modes of evaporation, quenching, and single-phase convection during subcooled nucleate boiling on a vertical wall. For the experimental partitioning of the wall heat flux, the wall heat flux and liquid-vapor distributions were simultaneously obtained using synchronized infrared thermometry and the total reflection technique. Boiling experiments of water with subcooling of
were conducted under atmospheric pressure, and the results obtained at the wall superheat of
and average heat flux of
were analyzed. There was a large difference in the heat flux partitioning results between the experiment and correlation, and the bubble departure diameter and bubble influence factor, which account for a portion of the surrounding superheated liquid layer detached by the departure of a bubble, were found to be important fundamental boiling parameters.
Experimental Feasibility Study on Low-Temperature Differential Stirling Engines with Water Spray Heat Transfer
Jang, Seon-Jun ; Lee, Yoon-Pyo ; Sim, Kyuho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 475~482
DOI : 10.3795/KSME-B.2014.38.6.475
This paper presents the results of an experimental feasibility study on low-temperature differential Stirling engines with water spray heat transfer. The water spray enhances the efficiency of the heat transfer from heat sources to the engine and reduces the performance degeneration due to the dead volumes of conventional heat exchangers. A test Stirling engine was developed and an experiment was conducted to determine the characteristics for the initial start-up, steady-state operation, and power output for various flow rates and temperatures of hot supply water. The test results showed that larger flow rates led to reductions in the minimum working temperature of the hot water at start-up. During a series of steady-state operations, higher flow rates and temperatures increased the working speed. Furthermore, the work per cycle and power output were also increased. Eventually, the test Stirling engine had a power level of 0.05 W. Based on this, further research will be conducted to obtain a higher power output and investigate various applications.
Thermodynamic Performance Analysis of Ammonia-Water Power Generation System Using Low-temperature Heat Source and Liquefied Natural Gas Cold Energy
Kim, Kyoung Hoon ; Kim, Kyung Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 483~491
DOI : 10.3795/KSME-B.2014.38.6.483
In this study, a thermodynamic analysis was carried out for a combined power generation system using a low-temperature heat source in the form of sensitive energy and liquefied natural gas cold energy. An ammonia-water mixture, which is a zeotropic mixture, was used as the working fluid, and systems with and without a regenerator were comparatively analyzed. The effects of the mass fraction of ammonia and the condensation temperature of the working fluid on the system variables, including the net work production, exergy destruction, and thermal and exergy efficiencies, are analyzed and discussed. The results show that the performance characteristics of the system varied sensitively with the ammonia concentration or condensation temperature of the working fluid. The system without regeneration was found to be better in relation to the net work per unit mass of the source fluid, whereas the system with regeneration was better in relation to the thermal or exergy efficiency.
Numerical Analysis of Characteristics of Cellular Counterflow Diffusion Flames near Radiative Extinction Limit
Lee, Su Ryong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 493~500
DOI : 10.3795/KSME-B.2014.38.6.493
Nonlinear characteristics of cellular counterflow diffusion flame near the radiative extinction limit at large Damk
hler number are numerically investigated. Lewis number is assumed to be 0.5 and flame evolution is calculated by imposing an infinitesimal disturbance to a one-dimensional(1-D) steady state flame. The early stage of nonlinear development is very similar to that predicted in a linear stability analysis. The disturbance with the wavenumber of the fastest growing mode emerges and grows gradually. Eventual, an alternating pattern of reacting and quenching stripes is developed. The cellular flame temperature is higher than that of 1-D flame because of the gain of the total enthalpy. As the Damk
hler number is further increased, the shape of the cell becomes circular to increase the surface area per unit reacting volume. The cellular flames do not extinguish but survive even above the 1-D steady state extinction condition.
Combustion and Emission Characteristics of High-Compression-Ratio Diesel Engine Fueled with Bio Oil-Ethanol Blended Fuel
Kim, Tae Young ; Lee, Seok Hwan ; Jang, Young Woon ; Kim, Ho Seung ; Kang, Kern Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 501~511
DOI : 10.3795/KSME-B.2014.38.6.501
Bio-oil derived from biomass through fast pyrolysis process has the potential to displace a significant amount of petroleum fuels. However, the use of bio-oil in a diesel engine is very limited because of its poor properties, e.g., its low energy density, low cetane number, and high viscosity. Therefore, bio-oil should be emulsified or blended with other fuels that have high centane numbers. Because bio-oil has poor miscibility with petroleum fuels, the most suitable candidate fuels for direct mixing are alcohol fuels. In this study, bio-oil was blended with ethanol, and two types of cetane improvers were added to a blended fuel to improve the self-ignition property. The two types of cetane improvers, PEG 400 and 2-EHN, made it possible for bio-oil blended fuels to combust in a diesel engine with a maximum bio-oil content of 15 wt%. A high-compression-ratio piston is also proposed for the combustion of bio-oil in a diesel engine.
Droplet Transport Mechanism on Horizontal Hydrophilic/Hydrophobic Surfaces
Myong, Hyon Kook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 513~523
DOI : 10.3795/KSME-B.2014.38.6.513
A fluid transport technique is a key issue for the development of microfluidic systems. In this study, the movement of a droplet on horizontal hydrophilic/hydrophobic surfaces, which is a new concept to transport droplets without external power sources that was recently proposed by the author, was simulated using an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The droplet transport mechanism is examined through numerical results that include velocity vectors, pressure contours, and total kinetic energy inside and around the droplet.
Numerical Simulations of Dynamic Response of Cased Reactive System Subject to Bullet Impact
Kim, Bohoon ; Kim, Minsung ; Doh, Youngdae ; Kim, Changkee ; Yoo, Jichang ; Yoh, Jai-Ick ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 525~538
DOI : 10.3795/KSME-B.2014.38.6.525
Safety of reactive systems is one of the most important research areas in the field of weapon development. A NoGo response or at least a low-order explosion should be ensured to prevent unexpected accidents when the reactive system is impacted by high-velocity projectile. We investigated the shock-induced detonation of cased reactive systems subject to a normal projectile impact to the cylindrical surface based on two-dimensional hydrodynamic simulations using the I&G chemical rate law. Two types of energetic materials, namely LX-17 and AP-based solid propellant, were considered to compare the dynamic responses of the reactive system when subjected to the threshold impact velocity. It was found that shock-to-detonation transition phenomena occurred in the cased LX-17, whereas no full reaction occurred in the propellant.
Comparison of Contact Resistivity Measurements of Silver Paste for a Silicon Solar Cell Using TLM and CTLM
Shin, Dong-Youn ; Kim, Yu-Ri ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 539~545
DOI : 10.3795/KSME-B.2014.38.6.539
Contact resistivity between silver electrodes and the emitter layer of a silicon solar cell wafer has been measured using either the circular transmission line method or the linear transmission line method. The circular transmission line method has an advantage over the linear transmission line method, in that it does not require an additional process for mesa etching to eliminate the leakage current. In contrast, the linear transmission line method has the advantage that its specimen can be acquired directly from a silicon solar cell. In this study, measured resistance data for the calculation of contact resistivity is compared for these two methods, and the mechanism by which the linear transmission line method can more realistically reflect the impact of the width and thickness of a silver electrode on contact resistivity is investigated.
Shape Optimization of Impeller Blades for 15,000 HP Centrifugal Compressor Using Fluid Structural Interaction Analysis
Kang, Hyun Su ; Oh, Jeongsu ; Han, Jeong Sam ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 6, 2014, Pages 547~556
DOI : 10.3795/KSME-B.2014.38.6.547
This paper discusses a one-way fluid structural interaction (FSI) analysis and shape optimization of the impeller blades for a 15,000 HP centrifugal compressor using the response surface method (RSM). Because both the aerodynamic performance and the structural safety of the impeller are affected by the shape of its blades, shape optimization is necessary using the FSI analysis, which includes a structural analysis for the induced fluid pressure and centrifugal force. The FSI analysis is performed in ANSYS Workbench: ANSYS CFX is used for the flow field and ANSYS Mechanical is used for the structural field. The response surfaces for the FSI results (efficiency, pressure ratio, maximum stress, etc.) generated based on the design of experiments (DOE) are used to find an optimal shape for the impeller blades, which provides the maximum aerodynamic performance subject to the structural safety constraints.