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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The KSFM Journal of Fluid Machinery
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Journal DOI :
Korean Fluid Machinery Association
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Volume & Issues
Volume 18, Issue 6 - Dec 2015
Volume 18, Issue 5 - Oct 2015
Volume 18, Issue 4 - Aug 2015
Volume 18, Issue 3 - Jun 2015
Volume 18, Issue 2 - Apr 2015
Volume 18, Issue 1 - Feb 2015
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Structural Analysis on the Arm and Floater Structure of a Wave Energy Converter
Chen, Zhenmu ; Singh, Patrick Mark ; Choi, Young-Do ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 5~11
DOI : 10.5293/kfma.2015.18.3.005
Ocean waves have huge amounts of energy, even larger than wind or solar, which can be extracted by some mechanical device. This can be done by creating a system of reacting forces, in which two or more bodies move relative to each other, while at least one body interacts with the waves. This moves the floater up and down. The floaters are connected to an arm structure, which are mounted on a fixed hull structure. Hence, the structure of the floater is very important. A static structural analysis with FSI (Fluid-Structure Interaction) analysis is conducted. To achieve the pressure load for the FSI analysis, the floater is simulated on a wave generator using rigid body motion. The structural analysis is done to examine the stresses on the whole system, and four types of flange and floater are optimized. The result shows that the structure of floater with wood support is the safest.
A Combined Rotary Compressor-vane Expander
Kim, Hyun Jin ; No, Young Jae ; Kim, Yong Hee ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 12~19
DOI : 10.5293/kfma.2015.18.3.012
As a means of improving cycle performance of a R410A air-conditioning system, a combined structure of compressor and expander was introduced. A vane rotary type expander was designed to share a common shaft with twin type rolling piston rotary compressor in a housing. Numerical simulation on the performance of the combined compressor and expander was carried out. At ARI condition, the volumetric and total efficiencies of the designed vane expander were 69.37% and 30.23%, respectively. With the application of this expander, the compressor input was reduced by 3.91%, and the cooling capacity was increased by 3.98%. As a result, COP of the air-conditioning system was improved by 8.2%. As the pressure difference between the condenser and the evaporator becomes large, COP improvement increases unless the mass flow rate in the expander exceeds that in the compressor.
Flow Characteristics of Floating Roof Tank with Varying the Number of Operation and Angle
Kim, Noh-Hyeong ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 20~25
DOI : 10.5293/kfma.2015.18.3.020
In this study, there are 6 mixers that are installed in a 600,000 barrel tank. We identified internal flow characteristics of floating roof tank with varying the number of operation from 4 to 6 because mixer is a variable that influence flow characteristics of the tank. And while varying an angle from Right
, we identified internal flow characteristics of the tank. As a result, maximum velocity of flow was 0.02m/s stationarily when we changed the number of operation from 4 to 6. Maximum velocity of flow by change of an angle was from 0.42m/s to 0.47m/s. Therefore, we identified that these factors don`t have a great influence on internal flow characteristics of a tank by investigating results with varying the number of operation and an angle.
Theatrical Research an Generated Power of Float-Counterweight Wave Converters
Lee, Sung-Bum ; Lee, Seung-Keon ; Moon, Byung-Young ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 26~32
DOI : 10.5293/kfma.2015.18.3.026
The authors are developing a motion of floater body type wave energy converter of the float-counterweight system. This consists of the driving pulley, wire, float and counterweight suspended from idler pulleys and rachet mechanism. Though it has succeeded in solving the major structural strength problem in which the floats would slam against adjacent structure(s) by wave load acting horizontally. In order to overcome this problem. We propose a new system in which the wire transmitting the power is wound around the pulleys and the float receiving the wave power is pulled by the wire from both its upper and lower ends to avoid the occurrence of slackening during the wave cycle. In the paper, we developed the dynamics model for the proposed system. Energy gain has been calculated for realistic wave conditions and compared with the original float-counterweight device. The important differences from the float-counterweight system are that (1) both upward and downward motions of water surface can be utilized without problem. (2) slackening of energy gain and wire tension are effectively suppressed, and (4) for the same time averaged energy gain, the maximum wire tension is fairly lowered.
Study on the Cooling Performance of Heatsink for Induction Cooktop using Computational Fluid Dynamics
Park, Dong Ho ; Kwon, Myoung Keun ; Lee, Dong Beom ; Seo, Eung Ryeol ; Park, Yong Jong ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 33~37
DOI : 10.5293/kfma.2015.18.3.033
A numerical study on the IPM/Bridge Diode cooling and coil cooling has been performed. Results are presented as plots of thermal resistance, temperature drop and RPM-ratio. CFD analysis for conventional cooling system has been performed as a reference case. As the RPM-Ratio was increased, heatsink thermal resistance and coil temperature were decreased. IPM/Bridge Diode thermal resistance and temperature of the coil is tended to be trade-off. The temperature of coil closest to the AC-motor fan showed the most significant change in accordance with duct design. The temperature of coil located at the top of DC-motor fan showed the most significant variation as the cooling air passes the heatsink fin area.
Study on the Conjugate Heat Transfer Analysis Methodology of Thermal Barrier Coating on the Internal Cooled Nozzle
Kim, Inkyom ; Kim, Jinuk ; Rhee, Dong-Ho ; Cho, Jinsoo ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 38~45
DOI : 10.5293/kfma.2015.18.3.038
In this study, two computational methodologies were compared to consider an effective conjugate heat transfer analysis technique for the cooled vane with thermal barrier coating. The first one is the physical modeling method of the TBC layer on the vane surface, which means solid volume of the TBC on the vane surface. The second one is the numerical modeling method of the TBC layer by putting the heat resistance interface condition on the surface between the fluid and solid domains, which means no physical layer on the vane surface. For those two methodologies, conjugate heat transfer analyses were conducted for the cooled vane with TBC layer having various thickness from 0.1 mm to 0.3 mm. Static pressure distributions for two cases show quite similar patterns in the overall region while the physical modeling shows quite a little difference around the throat area. Thermal analyses indicated that the metal temperature distributions are quite similar for both methods. The results show that the numerical modeling method can reduce the computational resources significantly and is quite suitable method to evaluate the overall performance of TBC even though it does not reflect the exact geometry and flow field characteristics on the vane surface.
Reliability Investigation of a Pump-Turbine System at Various Operating Conditions
Chen, Chengcheng ; Singh, Patrick Mark ; Choi, Young-Do ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 46~52
DOI : 10.5293/kfma.2015.18.3.046
Pump-turbine system is widely used by the hydropower industry for stabilizing the electrical grid in the vast growing economy of most developed countries. This study only investigates the Fluid-structure Interaction (FSI) analysis of the pump-turbine system at various operating conditions. The FSI analysis can show how reliable each component of the system is by providing the engineer with a better understanding of high stress and deformation points, which could reduce the lifespan of the pump-turbine. Pump-turbine components are categorized in two parts, pressurized static parts and movable stressed parts. The fixed parts include the spiral casing, top and bottom cover, stay vane and draft tube. The movable parts include guide vanes and impeller blades. Fine hexahedral numerical grids were used for CFD calculation and fine tetrahedral grids were used for structural analysis with imported load solution mapping greater than 90 %. The maximum equivalent stress are much smaller than the material yield stress, and the maximum equivalent stress showed an increasing tendency with the varying of operating conditions from partial to excessive at both modes. In addition, the total deformation of all the operating conditions showed a small magnitude, which have quite small influence on the structural stability. It can be conjectured that this system can be safely implemented.
A Design of 10 kW Class Counter-Rotating Tidal Turbine Focusing on the Improvement of Operating Performance
Hoang, Anh Dung ; Kim, Bu-Gi ; Kim, Jun-Ho ; Yang, Chang-Jo ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 53~59
DOI : 10.5293/kfma.2015.18.3.053
Tidal turbine, which is relatively similar to wind turbine in term of operational principle, has become a potential solution for the sustainable development of global energy. This paper introduces author`s work on tidal turbine which aims to improve the power efficiency by the adaption of counter-rotating concept. The turbine system is modelled and analyzed using computational simulation commercial code. Compared with other works, the counter-rotating tidal turbine presented here is expected to operate stably with high performance throughout a wide range of tip-speed-ratio. Moreover, the equability of individual performance of each rotor is an advantage.
Performance Characteristics and Efficiencies of Micro-Hydro Pelton Turbine with Nozzle Diameter Variation
Jo, In Chan ; Park, Joo Hoon ; Shin, Youhwan ; Kim, Kwang Ho ; Chung, Jin Taek ; Kim, Dong Ik ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 60~65
DOI : 10.5293/kfma.2015.18.3.060
This paper deals with performance characteristics and efficiencies of Pelton turbine can be applied as one of ERDs (Energy Recovery Devices) of PRO (Pressure Retarded Osmosis) system for desalination. The objective of this study is experimentally estimating the performance of micro-scale Pelton turbine for PRO pilot plant. Especially the performance characteristics with variations of jet nozzle diameter of Pelton turbine are discussed in detail. In order to do this, lab scale test rig of Pelton turbine was made for performance test, which includes water tank, Pelton wheel with buckets, jet nozzle and torque brake and so on. The parameter effects related on Pelton turbine`s efficiency were investigated and discussed on the influence of the variations of load and speed ratio.
Effects of Geometry of a Boot-Shaped Rib on Heat Transfer and Pressure Drop
Seo, Jae-Won ; Kim, Jun-Hee ; Kim, Kwang-Yong ;
The KSFM Journal of Fluid Machinery, volume 18, issue 3, 2015, Pages 66~73
DOI : 10.5293/kfma.2015.18.3.066
This paper deals with a parametric study on boot-shaped ribs in a rectangular cooling channel. Numerical analysis of the flow and heat transfer was performed using three-dimensional Reynolds averaged Navier-Stokes equations with the Speziale, Sarkar and Gatski turbulence model. The parametric study was performed for the parameters, tip width-to rib width, tip height-to-rib height, rib height-to-channel height, and rib height-to-width ratios. To assess the cooling performance and friction loss, Numsselt number and friction factor were defined as the performance parameter, respectively. The results showed that the cooling performance and friction loss were seriously affected by the four geometric parameters.