Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of computational fluids engineering
Journal Basic Information
Journal DOI :
Korea Society of Computational Fluids Engineering
Editor in Chief :
Volume & Issues
Volume 13, Issue 4 - Dec 2008
Volume 13, Issue 3 - Sep 2008
Volume 13, Issue 2 - Jun 2008
Volume 13, Issue 1 - Mar 2008
Selecting the target year
AERODYNAMIC ANALYSIS OF SUB-ORBITAL RE-ENTRY VEHICLE
Kim, C.W. ; Lee, Y.G. ; Lee, D.S. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 1~7
For Aerodynamic analysis of vehicle at altitude, 100km, the validity of governing equations based on continuum model, was reviewed. Also, as the preliminary study for the sub-orbital space plane development, a candidate geometry was suggested and computational fluid dynamic(CFD) analysis was performed for various angles of attack in subsonic and supersonic flow regimes to analyze the aerodynamic characteristics and performance. The inviscid flow analyses showed that the stall starts at angle of attack above
, the maximum drag is generated at angle of attack,
and the maximum lift to drag ratio is about 8 in subsonic flow. In supersonic, the stall angle is about
and the maximum drag is generated at angle of attack,
. Also, mach number distribution of re-entry vehicle was computed versus altitudes.
ASYMMETRIC VORTEX CHARACTERISTICS AT A CONE UNDER SUPERSONIC HIGH ANGLE OF ATTACK FLOW
Park, M.Y. ; Noh, K.H. ; Park, S.H. ; Lee, J.W. ; Byun, Y.H. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 8~13
A supersonic viscous flow over a five-degree half-angle cone is studied computationally with three-dimensional Navier-Stokes equations. Steady asymmetric solutions show that the asymmetric flow separation is caused by convective instability. The effects of angle of attacks, Reynolds numbers, and Mach numbers have been investigated and it is found that those factors affect the generation of the side force. The side force has the maximum value at
, while over
, asymmetric vortex becomes transient, which results in the unsteady shedding. At the angle of attack of 22 degrees, the side force increases with Reynolds number and decreases with Mach number. The increase of the side force stops over the critical Reynolds number for the present configuration.
EFFECTS OF THE REYNOLDS AND KNUDSEN NUMBERS ON THE FLOW OF A MICRO-VISCOUS PUMP
Kang, D.J. ; Ivanova, Ivelina Ivanova ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 14~19
Effects of the Reynolds and Knudsen numbers on a micro-viscous pump are studied by using a Navier-Stokes code based on a finite volume method. The micro viscous pump consists of a circular rotor and a two-dimensional channel. The channel walls are treated by using a slip velocity model. The Reynolds number is studied in the range of
. The Knudsen number varies from 0.01 to 0.1. Numerical solutions show that the pump works efficiently when two counter rotating vortices formed on both sides of the rotor have the same size and intensity. As the Reynolds number increases, the size and intensity of the vortex on the inlet side of the pump decrease. It disappears when the Reynolds number is larger than about Re=20. The characteristics of the performance of the pump is shown to deteriorate, in terms of mean velocity and pressure rise, as the Reynolds number increases. The Knudsen number shows a different effect on the characteristics of the pump. As it increases, the mean velocity and pressure rise decrease but the characteristics of the vortex flow remains unchanged, unlike the effect of Reynolds number.
ANALYSIS OF TURBULENT HEAT TRANSFER FROM STAGGERED PIN-FIN ARRAYS WITH DIAMOND SHAPED ELEMENTS AT VARIOUS GEOMETRICAL CONFIGURATIONS
Cho, A.T. ; Kim, K.Y. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 20~26
A numerical study is carried out to analyze the steady three-dimensional turbulent flow and convective heat transfer in a staggered pin-fin array with diamond shaped elements at various geometrical configurations. Steady Reynolds-averaged Navier-Stokes equations and energy equation are solved using a finite volume based solver. Shear stress transport (SST) model is used as turbulence closure. The computational domain is composed of one pitch of pin-fin displacement with periodic boundary conditions on the surfaces normal to the streamwise direction and the cross-streamwise direction. The numerical results for Nusselt number and friction factor are validated with experimental results. The effects of pin angle, pin height and pitch on Nusselt number, friction factor and efficiency index are investigated.
DEVELOPMENT OF AN UNSTRUCTURED HYBRID MESH FLOW SOLVER FOR 3-D STEADY/UNSTEADY INCOMPRESSIBLE FLOW SIMULATIONS
Jung, Mun-Seung ; Kwon, Oh-Joon ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 27~41
An unstructured hybrid mesh flow solver has been developed for the simulation of three-dimensional steady and unsteady incompressible flow fields. The incompressible Navier-Stokes equations with an artificial compressibility method were discretized by using a node-based finite-volume method. For the unsteady time-accurate computation, a dual-time stepping method was adopted to satisfy a divergence-free flow field at each physical time step. An implicit time integration method with local time stepping was implemented to accelerate the convergence in the pseudo-time sub-iteration procedure. The one-equation Spalart-Allmaras turbulence model has been adopted to solve high-Reynolds number flow fields. The flow solver was parallelized to minimize the CPU time and to overcome the computational overhead. This method has been applied to calculate steady and unsteady flow fields around submarine configurations and a 3-D infinite cylinder. Validations were made by comparing the predicted results with those of experiments or other numerical results. It was demonstrated that the present method is efficient and robust for the prediction of steady and unsteady incompressible flow fields.
HEAT TRANSFER ON TWO NEARBY CIRCULAR CYLINDERS
Han, T.H. ; Yang, K.S. ; Yoon, D.H. ; Lee, K. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 42~47
Heat transfer on two identical nearby circular cylinders immersed in the uniform cross flow at Re=120 and Pr=0.7 was numerically studied. We consider all possible types of arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of heat transfer are noticed depending on how the two circular cylinders are positioned, resulting in quantitative changes of heat transfer coefficients on both cylinders. Collecting all the numerical results obtained, we propose a contour diagram for averaged Nusselt number for each of the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate heat transfer rates on two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.
TRANSFER ORBIT THERMAL ANALYSIS FOR COMS
Jun, Hyoung-Yoll ; Kim, Jung-Hoon ; Kim, Sung-Hoon ; Yang, Koon-Ho ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 48~54
COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be launched by ARIANE 5. Ka-band components are installed on South panel, where single solar array wing is mounted. Radiators, embedded heat pipes, external heat pipe, insulation blankets and heaters are utilized for the thermal control of the satellite. The Ka-band payload section is divided several areas based on unit operating temperature in order to optimize radiator area and maximize heat rejection capability. Other equipment for sensors and bus are installed on North panel. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. During the transfer orbit operation, satellite will be under severe thermal environments due to low dissipation of components, satellite attitudes and LAE(Liquid Apogee Engine) firing. This paper presents temperature and heater power prediction and validation of thermal control design during transfer orbit operation.
ROTATING FLOW ANALYSIS AROUND A HAWT ROTOR BLADE USING RANS EQUATIONS
Kim, T.S. ; Lee, C. ; Son, C.H. ; Joh, C.Y. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 55~61
The Reynolds-Averaged Navier-Stokes(RANS) analysis of the 3-D steady flow around the NREL Phase VI horizontal axis wind turbine(HAWT) rotor was performed. The CFD analysis results were compared with experimental data at several different wind speeds. The present CFD model shows good agreements with the experiments both at low wind speed which formed well-attache flow mostly on the upper surface of the blade, and at high wind speed which blade surface flow completely separated. However, some discrepancy occurs at the relatively high wind speeds where mixed attached and separated flow formed on the suction surface of the blade. It seems that the discrepancy is related to the onset of stall phenomena and consequently separation prediction capability of the current turbulence model. It is also found that strong span-wise flow occurs in stalled area due to the centrifugal force generated by rotation of the turbine rotor and it prevents abrupt reduction of normal force for higher wind speed than the designed value.
NUMERICAL INVESTIGATION ON STATIC STIFFNESS CHARACTERISTICS OF POROUS AIR BEARING CONSIDERING ROUGHNESS EFFECTS
Gwon, H.R. ; Lee, S.H. ; Lee, J.E. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 62~67
This study aims to investigate numerically the static stiffness characteristics of porous air bearing and to estimate appropriate permeability values of porous medium. In particular, a new roughness model is proposed and implemented into the commercial CFD code (FLUENT Ver. 6.2) by using C language based user subroutine. The predicted results are extensively compared with experimental data. The roughness model is also validated through comparison with the results from open literature. It is found that the predictions for static stiffness are in good agreement with experimental data. Therefore, the suggested model based on the roughness Reynolds number can be used in studying the stiffness characteristics of porous air bearing effectively. In addition, numerical simulations of various diameter size and conditions are conducted. According the results, it is expected that the static stiffness of porous air bearing has the non-linear characteristics.
DEVELOPMENT OF A GENERAL PURPOSE THERMO/FLUID FLOW ANALYSIS PROGRAM NUFLEX WITH WALL IMPINGEMENT AND HEAT TRANSFER ANALYSIS MODEL OF LIQUID FILM
Kim, H.J. ; Ro, K.C. ; Ryou, H.S. ; Hur, N. ;
Journal of computational fluids engineering, volume 13, issue 2, 2008, Pages 68~72
NUFLEX is a general purpose thermo/fluid flow analysis program which has various physical models including spray. In NUFLEX, spray models are composed of breakup and collision models of droplet. However, in case of diesel engine, interaction between wall-film and impingement model considering heat transfer is not coded in NUFLEX. In this study, Lee & Ryou impingement & wall-film model considering heat transfer is applied to NUFLEX. For the verification of this NUFLEX program, numerical results are compared with experimental data. Differences of film thickness and radius between numerical results and experimental data are within 10% error range. The results show that NUFLEX can be used for comprehensive analysis of spray phenomena.