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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of computational fluids engineering
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Journal DOI :
Korea Society of Computational Fluids Engineering
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Volume & Issues
Volume 14, Issue 4 - Dec 2009
Volume 14, Issue 3 - Sep 2009
Volume 14, Issue 2 - Jun 2009
Volume 14, Issue 1 - Mar 2009
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SHAPE OPTIMIZATION OF A Y-MIXING VANE IN NUCLEAR FUEL ASSEMBLY
Jung, S.H. ; Kim, K.Y. ; Kim, K.H. ; Park, S.K. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 1~8
The purposes of present work are to analyze the convective heat transfer with three-dimensional Reynolds-averaged Navier-Stokes analysis, and to optimize shape of the mixing vane taken tolerance into consideration by using the analysis results. Response surface method is employed as an optimization technique. The objective function is defined as a combination of heat transfer rate and inverse of pressure drop. Two bend angles of mixing vane are selected as design variables. Thermal-hydraulic performances have been discussed and optimum shape has been obtained as a function of weighting factor in the objective function. The results show that the optimized geometry improves the heat transfer performance far downstream of the mixing vane.
LIQUID FLOW AND EVAPORATION SIMULATION OF CRYOGENIC FLUID IN THE WALL OF CRYOGENIC FLUID CARGO CONTAINMENT SYSTEM
Park, Bum-Jin ; Lee, Hee-Bum ; Rhee, Shin-Hyung ; Bae, Jun-Hong ; Lee, Kyung-Won ; Jeong, Wang-Jo ; An, Sang-Jun ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 9~18
The cargo containment system (CCS) for ships carrying cryogenic fluid consists of at least two levels of barriers and insulation layers. It is because, even though there is a small amount of leak through the primary barrier, the liquid tight secondary barrier blocks further leakage of the cryogenic fluid. However, once the secondary barrier is damaged, it is highly possible that the leaked cryogenic fluid flows through the flat joint made of glass wool and reaches the inner hull of the ship. The primary objective of the present study is to investigate the influence of the damage extent in the secondary barrier on the amount of leaked cryogenic fluid reaching the inner hull and the temperature distribution there. Simulation results using a computational fluid dynamics tool were compared with the experimental data for the leaked cryogenic fluid flow and evaporation in the secondary insulation layer. The experimental and computational results suggest that, unless there is a massive leak, the cryogenic fluid mostly evaporates in the insulation layer and does not reach the inner hull in the state of liquid.
NUMERICAL STUDY OF FLOW PATTERNS PAST AN INCLINED SQUARE CYLINDER
Yoon, Dong-Hyeog ; Yang, Kyung-Soo ; Choi, Choon-Bum ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 19~24
A parametric study has been carried out to elucidate the characteristics of flow past a square cylinder inclined with respect to the main flow for Re
150. Reynolds number and angle of incidence are the key parameters which determine the flow characteristics. This study would be the first step towards understanding flow pattern past a cylindrical structure under a strong gust of wind from the viewpoint of wind hazards. A complete classification of flow pattern has been obtained in the laminar region.
AERODYNAMIC DESIGN OPTIMIZATION OF ROTOR BLADE OA AIRFOILS
Sa, J.H. ; Park, S.H. ; Kim, C.J. ; Yun, C.Y. ; Kim, S.H. ; Kim, S. ; Yu, Y.H. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 25~31
Numerical optimization of rotor blade airfoils is performed with a response surface method for helicopter rotor. For the baseline airfoils, OA 312, OA 309, and OA 407 airfoils are selected and optimized to improve aerodynamic performance. Aerodynamic coefficients required for the response surface method are obtained by using Navier-Stokes solver with k-
Shear Stress Transport turbulence model. An optimized airfoil has increased drag divergence Mach number. The present design optimization method can generate an optimized airfoil with multiple design constraints, whenever it is designed from different baseline airfoils at the same design condition.
THE NUMERICAL SIMULATION OF HYDROGEN JET DIFFUSION FOR HYDROGEN LEAKAGE IN THE ENCLOSED GEOMETRY
Ahn, Hyuk-Jin ; Lee, Sang-Hyuk ; Hur, Nahm-Keon ; Lee, Moon-Kyu ; Yong, Gee-Joong ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 32~38
In the present study, a numerical simulation for the diffusion of hydrogen jet in a enclosure was performed to aid the leakage test of the hydrogen for the safety of the hydrogen vehicle. The temporal and spatial distributions of the hydrogen concentration in the test chamber are predicted from the present numerical analyses. Flammable region of 4-74% and explosive region of 18-59% hydrogen by volume was identified from the present results. Factors influencing the diffusion of the hydrogen jet were examined to evaluate the effectiveness of forced ventilation for relieving the accumulation of the leaked hydrogen gas in the chamber, which include location of open windows, size of leakage nozzle, and leakage rate among others. The distribution of the concentration of the leaked hydrogen for various cases can be used as a database in various applications for the hydrogen safety.
NUMERICAL STUDY FOR COOLING CAPACITY IMPROVEMENT OF ENGINE ROOM ENCLOSURE SYSTEM
Bae, Y.S. ; Yoo, G.J. ; Choi, H.K. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 39~45
In engine room, proper enclosure system is preferable for reducing noise level but the enclosure system in the engine room causes bad influence on cooling performance due to poor ventilation. Cooling efficiency of the enclosure system can be improved by varying fan speed and proper flow path for ventilation. In this study, numerical analysis is performed to assess cooling effect of the enclosure system using finite volume method. The RNG k-
model is adopted for turbulence model along with heat exchanger model and porous media model for heat exchanger analysis, and moving reference frame model for rotational fan. Verification result shows reasonable agreement with experimental data. Analysis results show direct effect of velocity and temperature distribution on cooling ability in the enclosure system. Enclosure system of case B shows high heat transfer coefficient and has the smallest area ratio of opened flow passages which is good for noise level reduction.
IMPLEMENTATION OF VELOCITY SLIP MODELS IN A FINITE ELEMENT NUMERICAL CODE FOR MICROSCALE FLUID SIMULATIONS
Hoang, A.D. ; Myong, R.S. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 46~51
The slip effect from the molecular interaction between fluid particles and solid surface atoms plays a key role in microscale fluid transport and heat transfer since the relative importance of surface forces increases as the size of the system decreases to the microscale. There exist two models to describe the slip effect: the Maxwell slip model in which the slip correction is made on the basis of the degree of shear stress near the wall surface and the Langmuir slip model based on a theory of adsorption of gases on solids. In this study, as the first step towards developing a general purpose numerical code of the compressible Navier-Stokes equations for computational simulations of microscale fluid flow and heat transfer, two slip models are implemented into a finite element numerical code of a simplified equation. In addition, a pressure-driven gas flow in a microchannel is investigated by the numerical code in order to validate numerical results.
TURBULENT FLOW AROUND AN INCLINED SQUARE CYLINDER
Yoon, Dong-Hyeog ; Yang, Kyung-Soo ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 52~58
Turbulent flow past an inclined square cylinder immersed in a cross stream is numerically investigated. The angle of incidence of main flow is one of the key factors determining at which edges the flow separates. In the present study, based on comprehensive numerical simulations, effects of inclination angle on the flow characteristics are elucidated and the related physical explanation is presented.
ASSESSMENT OF CORE BYPASS FLOW IN A PRISMATIC VERY HIGH TEMPERATURE REACTOR BY USING UNIT-CELL EXPERIMENT AND CFD ANALYSIS
Yoon, S.J. ; Jin, C.Y. ; Kim, M.H. ; Park, G.C. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 59~67
An accurate prediction of the bypass flow is of great importance in the VHTR core design concerning the fuel thermal margin. Nevertheless, there has not been much effort in evaluating the amount and the distribution of the core bypass flow. In order to evaluate the behavior and the distribution of the coolant flow, a unit-cell experiment was carried out. Unit-cell is the regular triangular section which is formed by connecting the centers of three hexagonal blocks. Various conditions such as the inlet mass flow rate, block combinations and the size of bypass gap were examined in the experiment. CFD analysis was carried out to analyze detailed characteristics of the flow distribution. Commercial CFD code FLUENT 6.3 was validated by comparing with the experimental results. In addition, SST model and standard k-
model were validated. The results of CFD simulation show good agreements with the experimental results. SST model shows better agreement than standard k-
model. Results showed that block combinations and the size of the bypass gap have an influence on the bypass flow ratio but the inlet mass flow rate does not.
A NUMERICAL STUDY ON FLOWS IN A FUEL TANK WITH BAFFLES AND POROUS MEDIA TO REDUCE SLOSHING NOISE
Lee, Sang-Hyuk ; Hur, Nahm-Keon ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 68~76
The sloshing tank causes the instability of the fluid flows and the fluctuation of the impact pressure by the liquid on the tank. These flow characteristics inside the sloshing tank can generate the uncomfortable sloshing noise. In the present study, a numerical analysis for the reduction of a fuel tank sloshing noise was performed. To simulate the flow characteristics in a sloshing tank with partially filled liquid, a VOF method was used for interfacial flows by applying a momentum source term for the sloshing motion in a non-inertial reference frame. This numerical method was verified by comparing its results with the available experimental data. For the reduction of the sloshing noise, the horizontal and vertical baffles and porous media inside a sloshing tank were considered and numerically analyzed in the present study. For various installations of these baffles and porous media, the characteristics of the liquid behavior in the sloshing tank were obtained along with the impact pressure on the wall and the height of the free surface along the wall. These basic results can be used for the design of the actual vehicular fuel tank with the reduced sloshing noise.
HEAT TRANSFER ON THE COMBUSTION CHAMBER OF A WATER TUBE TYPE BOILER WITH MULTIPLE BURNERS
Ahn, J. ; Hwang, S. ; Kim, J.J. ; Kang, S.B. ;
Journal of computational fluids engineering, volume 14, issue 2, 2009, Pages 77~83
Operating medium or large scale industrial boilers in partial load condition, the burner should undergo the off-design points resulting in poor exhaust gas characteristics. To obtain the stable turn down performance, two or more burners can be used for the industrial boiler. In case multiple burners are adopted, the heat transfer can be enhanced by arranging the burners properly. In the present study, numerical simulations have been conducted for the combustion chamber of a 2 t/h class industrial boiler in order to clarify the heat transfer characteristics at the combustion chamber.