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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 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
Flow Field Measurement in Catalytic Converter-Comparison with Computational Fluid Dynamics Analyses
Yoo, Seoung-Chool ; Jang, Sung-Kuk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 197~202
DOI : 10.3795/KSME-B.2014.38.3.197
The efficiency of a catalytic converter depends on the flow distribution across a system's chemically active substrate. If irregularities or non-uniform flow patterns exist, the system's conversion efficiency decreases, whereas the manufacturing cost increases. Therefore, it is important to analyze the internal flow of a catalytic converter. In this study, flow pattern measurements along the minor axis were recorded at the mid and exit planes of a ceramic honeycomb catalytic converter at flow rates of 37.8 l/s and 94.4 l/s. Flow distributions of the measurement plans were compared with an automotive company's computed velocity profiles. Measurements along the minor axis showed uneven velocity profiles. The
-velocity components between the honeycomb bricks were small but somewhat erratic opposite the intake side of the converter, however, they became flatter in measurements recorded near the intake entrance. For almost all velocity values, the computer model suggested velocities greater than the measured values.
Calculation of Hydrodynamic Characteristics of Weis-Fogh Type Water Turbine Using the Advanced Vortex Method
Ro, Ki Deok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 203~210
DOI : 10.3795/KSME-B.2014.38.3.203
In this study, the hydrodynamic characteristics of Weis-Fogh type water turbine were calculated by the advanced vortex method. The wing (NACA0010 airfoil) and both channel walls were approximated by source and vortex panels, and free vortices are introduced away from the body surfaces. The distance from the trailing edge of the wing to the wing axis, the width of the water channel and the maximum opening angle were selected as the calculation parameters, the important design factors. The maximum efficiency and the power coefficient for one wing of this water turbine were 26% and 0.4 at velocity ratio U/V=2.0 respectively. The flow field of this water turbine is very complex because the wing moves unsteadily in the channel. However, using the advanced vortex method, it could be calculated accurately.
Harmonized Non-linear Interaction Between Different Two Vortex Shedding Frequencies
Kim, Sang Il ; Seung, Sam Sun ; Lee, Seung-Chul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 211~217
DOI : 10.3795/KSME-B.2014.38.3.211
This study analyzes the nonlinear interaction between two different vortex shedding frequencies from a cylinder with two diameters. In particular, two different vortex shedding frequencies are generated by preparing a cylinder having two diameters artificially. Flow velocity fluctuations behind the cylinder are measured three-dimensionally. Additionally, we fabricated a hole and placed a pressure transducer for measuring the pressure on the cylinder surface. The pressure signal from the pressure transducer is used as basic signal. A TSC(Trans Spectrum Coherence) is used for checking the strength of the nonlinear interaction between two different vortex shedding frequencies. As a result, the following are clarified: i) frequency distribution behind the cylinder, ii) three-dimensional flow state behind the cylinder through calculation of ensemble average, and iii) close relationship between the vertical vortex and change of low frequency by nonlinear interaction between two different vortex shedding frequencies from the cylinder with two diameters.
A Numerical Study of the Effect of Non-equilibrium Condensation on the Oscillation of Shock Wave in a Transonic Airfoil Flow
Jeon, Heung Kyun ; Kim, In Won ; Kwon, Young Doo ; Kwon, Soon Bum ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 219~225
DOI : 10.3795/KSME-B.2014.38.3.219
In this study, to find the characteristics of the oscillation of a terminating shock wave in a transonic airfoil flow with non-equilibrium condensation, a NACA00-12,14,15 airfoil flow with non-equilibrium condensation is investigated through numerical analysis of TVD scheme. Transonic free stream Mach number of 0.81-0.90 with the variation of stagnation relative humidity and airfoil thickness is tested. For the free stream Mach number 0.87 and attack angle of
, the increase in stagnation relative humidity attenuates the strength of the terminating shock wave and inactivates the oscillation of the terminating shock wave. For the case of
, the decreasing rate in the frequency of the shock oscillation caused by non-equilibrium condensation to that of
amounts to 5%. Also, as the stagnation relative humidity gets larger, the maximum coefficient of drag and the difference between the maximum and minimum in
become smaller. On the other hand, as the thickness of the airfoil gets larger, the supersonic bubble size becomes bigger and the oscillation of the shock wave becomes higher.
One-Dimension Thermal Modeling of NiMH Battery for Thermal Management of Electric Vehicles
Han, Jaeyoung ; Park, Jisoo ; Yu, Sangseok ; Kim, Sung-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 227~234
DOI : 10.3795/KSME-B.2014.38.3.227
Fuel consumption rates of electric vehicles strongly depend on their battery performance. Because the battery performance is sensitive to the operating temperature, temperature management of the battery ensures its performance and durability. In particular, the temperature distribution among modules in the battery pack affects the cooling characteristics. This study focuses on the thermal modeling of a battery pack to observe the temperature distribution among the modules. The battery model is a prismatic model of 10 NiMH battery modules. The thermal model of the battery consists of heat generation, convective heat transfer through the channel and conduction heat transfer among modules. The heat generation is calculated by the electric resistance heat during the charge/discharge state. The model is used to determine a strategy for proper thermal management in Electric vehicles.
Numerical Investigation of Flow Structures near Various Nozzle Exit Geometries of the Air Bearing
Park, Byung Ho ; Han, Yong Oun ; Park, Sang-Shin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 235~242
DOI : 10.3795/KSME-B.2014.38.3.235
To investigate pressure distributions on the shaft surface of the air bearing, the commercial CFD software was employed to study three different nozzle geometries to improve the nozzle performance: general drill-shaped, matched cube-shaped and trimmed exit nozzles. Under the influence of stagnation point, the maximum pressure was observed at the center of shaft surface for all cases. Owing to the blocking effect of a fine gap between the shaft surface and the nozzle exit, the drill-shaped nozzle has the rapid local pressure increase near the nozzle exit corner, generating the ring vortex in the radial direction within pressure ratio of 6.92, and its pressure becomes negative in a certain range of downstream. In comparison, the contoured nozzle showed a local pressure increase in the measured range of pressure ratios, but a negative pressure appeared within the pressure ratio of about 10. The trimmed nozzle was seemed to extend the high pressure zone near the stagnation point in the radial direction substantially, and no negative pressure was appeared in the whole range. Based on these observations, it is found that trimming nozzle exit becomes more effective for improving the performance than modifying the nozzle inside contour.
Loss and Heat Transfer Analysis for Reliability in High Speed and Low Torque Surface Mounted PM Synchronous Motors
Choi, Moon Suk ; Um, Sukkee ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 243~254
DOI : 10.3795/KSME-B.2014.38.3.243
It is essential to predict the coil temperature under over load and over speed conditions for reliability in high speed low torque surface mounted PM synchronous motors(SPM). In the present study, the losses and coil temperature are measured under rated condition and calculated under over speed and over load conditions in the three different motors with 35PN440, 25PN250 and 15HTH1000. The heat transfer modeling has been performed based on acquired losses and temperature. The difference of coil temperature between heat transfer modeling and experiment is less than 6.4% under no load, over speed and over load conditions. Subsequently, the coil temperature of the motor with 15HTH1000 is 84.4% of the coil temperature of the motor with 35PN440 when speed is 0.9 and load is 3.0. The output of motor with 15HTH1000 is 85.2% greater than the output of the motor with 35PN440 when the dimensionless coil temperature is 1.0.
Experimental study on Effects of POE oil on R134a Evaporation Heat Transfer in Plate Heat Exchanger
Chang, Young Soo ; Jang, Jae Kyoo ; Kang, Byung Ha ; Kim, Sukhyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 255~262
DOI : 10.3795/KSME-B.2014.38.3.255
To investigate the effect of oil on evaporation heat transfer of plate heat exchanger, evaporation heat transfer experiment was carried out using experimental apparatus for micro gear pumped R134a-oil circulation. By varying oil circulation rate of POE oil from 0 to 5%, evaporation heat transfer performance of plate heat exchanger was investigated. As OCR(Oil Circulation Ratio) increases, the evaporation heat transfer coefficient of R134a decreases and pressure drop increases. When the evaporating temperature is
and the refrigerant mass flow rate is 80 g/s, evaporation heat transfer rate decreases by 10 % and pressure drop increases by 10% at 2% of OCR condition.
A New Concept to Transport a Droplet on Horizontal Hydrophilic/Hydrophobic Surfaces
Myong, Hyon Kook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 263~270
DOI : 10.3795/KSME-B.2014.38.3.263
A fluid transport technique is a key issue for the development of microfluidic systems. In this paper, a new concept for transporting a droplet without external power sources is proposed and verified numerically. The proposed device is a heterogeneous surface which has both hydrophilic and hydrophobic horizontal surfaces. The numerical simulation to demonstrate the new concept is conducted by an in-house solution code (PowerCFD) which 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. It is found that the proposed concept for droplet transport shows superior performance for droplet transport in microfluidic systems.
Numerical Study on the Effect of Reactor Internal Structure Geometry Treatment Method on the Prediction Accuracy for Scale-down APR+ Flow Distribution
Lee, Gong Hee ; Bang, Young Seok ; Woo, Sweng Woong ; Cheong, Ae Ju ;
Transactions of the Korean Society of Mechanical Engineers B, volume 38, issue 3, 2014, Pages 271~277
DOI : 10.3795/KSME-B.2014.38.3.271
Internal structures, especially those located in the upstream of a reactor core, may have a significant influence on the core inlet flow rate distribution depending on both their shapes and the relative distance between the internal structures and the core inlet. In this study, to examine the effect of the reactor internal structure geometry treatment method on the prediction accuracy for the scale-down APR+ flow distribution, simulations with real geometry modeling were conducted using ANSYS CFX R.14, a commercial computational fluid dynamics software, and the predicted results were compared with those of the porous medium assumption. It was concluded that the core inlet flow distribution could be predicted more accurately by considering the real geometry of the internal structures located in the upstream of the core inlet. Therefore, if sufficient computational resources are available, an exact representation of these internal structures, for example, lower support structure bottom plate and ICI nozzle support plate, is needed for the accurate simulation of the reactor internal flow.