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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of computational fluids engineering
Journal Basic Information
Journal DOI :
Korea Society of Computational Fluids Engineering
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Volume & Issues
Volume 15, Issue 4 - Dec 2010
Volume 15, Issue 3 - Sep 2010
Volume 15, Issue 2 - Jun 2010
Volume 15, Issue 1 - Mar 2010
Selecting the target year
LOW-SPEED AERODYNAMIC CHARACTERISTIC OF TRANSITION FLOW OVER THE NACA0012
Jeon, Sang-Eon ; Park, Soo-Hyung ; Kim, Sang-Ho ; Byun, Yung-Hwan ; Jung, Kyung-Jin ; Kang, In-Mo ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 1~8
Laminar separation bubble and transitional flow over the NACA0012 are investigated at a moderate range of Reynolds numbers. A Reynolds-Averaged Navier-Stokes code is coupled with an empirical transition model that can predict transition onset points and the length of transition region. Without solving the boundary layer equations, approximated e-N method is directly applied to the RANS code and iteratively solved together. The computational results are compared with the experimental data for the NACA0012 airfoil. Results of transition onset point and the length are compared well with experimental data and Xfoil prediction. The present RANS results show at high angles of attack better agreement with experimental data than Xfoil results using the boundary layer equations.
STUDY ON NUMERICAL ANALYSIS AND TURBULENCE MODELS FOR ARC DISCHARGES IN HIGH-VOLTAGE INTERRUPTERS
Lee, J.C. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 9~15
In this study, we calculated arc discharges and flow characteristics driven by arcs in a thermal puffer chamber, which is one of most outstanding high-voltage interrupters, for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE ablation, Cu evaporation, and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during the whole arcing history because the plasma flow is affected by high heat energy and mass momentum. Two turbulence models, the Prandtl's mixing length model and the standard
model, are applied for these calculations and are compared with pressure-rise inside chamber and arc voltage between the contacts as well as flow characteristics near current zero.
DESIGN OPTIMIZATION OF UPPER PLENUM OF PBMR USING RESPONSE SURFACE APPROXIMATION
Lee, S.M. ; Kim, K.Y. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 16~23
Shape optimization of an upper plenum of a PBMR type gas cooled nuclear reactor has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) analysis and surrogate modeling technique. The objective function is defined as a linear combination of uniformity of flow distribution in the core and pressure drop in the upper plenum and the core. The ratio of thickness of slot to diameter of rising channels, ratio of height of upper plenum to diameter of rising channels, and ratio of height of the slot at inlet to outlet, are used as design variables for optimization. Design points are selected through Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which uses 3-D RANS analyses at design points. The results show that the optimum shape represent remarkably improved performance in flow uniformity and friction loss than the reference shape.
NEAR-WALL GRID DEPENDENCY OF CFD SIMULATION FOR A SUBCOOLED BOILING FLOW USING WALL BOILING MODEL
In, W.K. ; Shin, C.H. ; Chun, T.H. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 24~31
boiling flow in vertical tube. The multiphase flow model used in this CFD analysis is the two-fluid model in which liquid(water) and gas(vapour) are considered as continuous and dispersed fluids, respectively. A wall boiling model is also used to simulate the subcooled boiling heat transfer at the heated wall boundary. The diameter and heated length of tube are 0.0154 m and 2 m, respectively. The system pressure in tube is 4.5 MPa and the inlet subcooling is 60 K. The near-wall grid size in the non-dimensional wall unit for lqiuid phase (
) was examined from 101 to 313 at the outlet boundary. The CFD calculations predicted the void distributions as well as the liquid and wall temperatures in tube. The predicted axial variations of the void fraction and the wall temperature are compared with the measured ones. The CFD prediction of the wall temperature is shown to slightly depend on the near-wall grid size but the axial void prediction has somewhat large dependency. The CFD prediction was found to show a better agreement with the measured one for the large near-wall grid, e.g.,
> 300 at the tube exit.
AERODYNAMIC DESIGN OF A MULTI-FUNCTION AIR DATA SENSOR BY USING CFD AND WIND TUNNEL TEST
Park, Y.M. ; Choi, I.H. ; Lee, Y.G. ; Kwon, K.J. ; Kim, S.C. ; Hwang, I.H. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 32~38
Aerodynamic design of the vane type multi-function probe was tried by using CFD and wind tunnel test for the MALE UAV and small business jets. The present multi-function probe can measure total pressure, static pressure and angle of attack by using rotating vane. Therefore, major performances are determined by aerodynamic characteristics of vane. In order to design the sensor compatible to the requirement, aerodynamic characteristics of sensors were investigated by using CFD and dynamic response analysis was also performed for transient performance. The final aerodynamic performance was measured by the wind tunnel test at Aerosonic and the results were compared with the present design. The results showed that the aerodynamic design using the CFD can be successfully used for the design of vane type multi-function air data sensor.
MEASUREMENT OF FLOW DISTRIBUTION IN A STRAIGHT DUCT OF RAILWAY TUNNEL MOCK-UP USING PIV AND COMPARISON WITH NUMERICAL SIMULATION
Jang, Y.J. ; Jung, W.S. ; Park, I.S. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 39~45
The turbulent flows in a tunnel mock-up(
m3 : scale reduction 1/20) with rectangular cross section were investigated. The instantaneous velocity fields of Re = 49,029, 89,571 were measured by the 2-D PIV system which is consisted of double pulsed Nd:Yag laser and the tracer particles in the straight-duct mock-up where the flows were fully developed. The mean velocity profiles were taken from the ensemble averages of 1,000 instantaneous velocity fields. Simultaneously, numerical simulations(RANS) were performed to compare with experimental data using STREAM code. Non-linear eddy viscosity model (NLEVM : Abe-Jang-Leschziner Eddy Viscosity Model) was employed to resolve the turbulent flows in the duct. The calculated mean velocity profiles were well compared with PIV results. In the log-law profiles, the experimental data were in good agreement with numerical simulations all the way to the wake region except the viscous sub-layer (near wall region).
REVIEW ON OPENFOAM - AN OPEN SOURCE SOFTWARE
Park, J.K. ; Kang, K.H. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 46~53
Recently, several open source codes for computational fluid dynamics (CFD) have been introduced and are spreading fast. Our group has chosen the OpenFOAM as a platform to develop our own in-house code. In this brief review, we would like to share the information on the codes and what we have experienced so far. We introduce several features of OpenFOAM, which include the performance compared with commercial packages, estimation for current user population, and our own prospect for future improvement in performance and growth in user population. In addition, we briefly introduce our experience gained in embedding the level set method into the OpenFOAM.
PRIMARY INSTABILITY OF THE CHANNEL FLOW WITH A STREAMWISE-PERIODIC ARRAY OF CIRCULAR CYLINDERS - EFFECTS OF THE DISTANCE BETWEEN THE CYLINDER AND THE CHANNEL WALL -
Yoon, D.H. ; Yang, K.S. ; Kang, C. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 54~59
A parametric study has been carried out to elucidate the characteristics of channel flow with a streamwise-periodic array of cylinders. This flow configuration is relevant to heat exchanger applications. The presence of cylinders in channel flow causes the attached wall boundary layer to separate, leading to significant change in flow instabilities. There exist two kinds of instabilities; flow undergoes a primary instability (Hopf bifurcation) at a lower Reynolds number, and the unsteady two-dimensional flow becomes unstable to three-dimensional disturbances at a higher Reynolds number. We report here the dependencies of the primary instability as well as the flow characteristics of the subsequent unsteady flow, including flow-induced forces and Strouhal number of vortex shedding, on the distance between the cylinder and the channel wall.
NUMERICAL INVESTIGATION OF THE EFFECT OF THE STAGGER ANGLE ON THE AERODYNAMIC PERFORMANCES IN THE VANED DIFFUSER OF A CENTRIFUGAL COMPRESSOR
Park, T.G. ; Jung, I.S. ; Chung, H.T. ; Park, J.Y. ; Kim, S.M. ; Baek, J.H. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 60~65
In the present study, the effects of the stagger angles on the aerodynamic performances in the vaned centrifugal compressor has been investigated by CFD methods. The diffuser vane angles were varied in the range of
deg. from the initial-design points. The commercial Navier-Stokes solver, ANSYS-CFX were applied to solve the impeller-diffuser flowfields. Through the numerical results, the desirable setting angles were proposed to fit the best performance to the variation of the operating conditions.
DEVELOPMENT OF THERMAL ANALYSIS PROGRAM FOR GEOSTATIONARY SATELLITE PANEL
Jun, Hyoung-Yoll ; Kim, Jung-Hoon ; Han, Cho-Young ; Chae, Jong-Won ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 66~72
The north and south panel of a geostationary satellite are used for radiator panels to reject internal heat and utilize several heat pipe networks to control the temperatures of units and the main structures of satellite within proper ranges. The design of these panels is very important and essential at the conceptual design and preliminary satellite design stage, so several thousands of nodes or more are utilized in order to perform detailed thermal analysis of panel. Generating a large number of panel nodes takes time and is tedious work because the nodes can be easily changed and updated by locations of units and heat pipes. Also the detailed panel model can not be integrated into spacecraft thermal model due to its node size and limitation of commercial satellite thermal analysis program. Thus development of a program was required to generate a detailed panel model, to perform thermal analysis and to make a reduced panel model for the integration to the satellite thermal model. This paper describes the development and the verification of the panel thermal analysis program with its main modules and functions.
EXACT RIEMANN SOLVERS FOR COMPRESSIBLE TWO-PHASE SHOCK TUBE PROBLEMS
Yeom, Geum-Su ; Chang, Keun-Shik ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 73~80
In this paper, we present the exact Riemann solver for the compressible liquid-gas two-phase shock tube problems. We hereby consider both isentropic and non-isentropic two-phase flows. The shock tube has a diaphragm in the mid-section which separates the liquid medium on the left and the gas medium on the right. By rupturing the diaphragm, various waves are observed on the phasic field variables such as pressure, density, temperature and void fraction in the form of rarefaction wave, shock wave and material interface (contact discontinuity). Both phases are treated as compressible fluids using the linearized equation of state or the stiffened-gas equation of state. We solve several shock tube problems made of a high/low pressure in the liquid and a low/high pressure in the gas. The wave propagations are well resolved by the exact Riemann solutions.
A NUMERICAL STUDY ON FLOW PATTERN IN CONNECTING PASSAGEWAY OF A COMPOSITE BUILDING
Jeon, B.J. ; Jang, B.Y. ; Choi, H.G. ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 81~86
In this paper, a three-dimensional numerical study on flow pattern in winter along connecting passageway of a composite building was conducted using a commercial CFD package. The incompressible Navier-Stokes equation coupled was solved by using SIMPLE algorithm in order to find steady solutions. It was shown that a upward flow is generated inside the building in winter due to buoyancy effect and that the air inside connecting passageway flows from the shorter building to the taller one regardless of the slope of the passageway. Further, it was found that the magnitude of air velocity inside connecting passageway increases as the uphill slope to the taller building increases and decreases as the downhill slope to the taller one increases, although the variation in the magnitude of fluid velocity is not substantial. Lastly, it was shown that the maximum air velocity inside connecting passageway is less than the allowable limit for all the cases considered in this study.
HYDROMAGNETIC FLOW IN A CAVITY WITH RADIATIVELY ACTIVE WALLS
Han, Cho-Young ; Chae, Jong-Won ; Kim, Jung-Hoon ; Jun, Hyoung-Yoll ;
Journal of computational fluids engineering, volume 15, issue 3, 2010, Pages 87~94
Hydromagnetic flow in a cavity under a uniform magnetic field is studied numerically. The cavity is comprised of four radiatively active surfaces. Due to large temperature difference inside a cavity, the radiative interaction between walls is taken into account. The coupled momentum and energy equations are solved by SIMPLER algorithm while the radiant heat exchanges are obtained by the finite volume method for radiation. A Wide range of Grashof numbers is examined as a controlling parameter. Resultant flow and heat transfer characteristics are investigated as well.