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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Aeronautical & Space Sciences
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Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 25, Issue 6 - Dec 1997
Volume 25, Issue 5 - Oct 1997
Volume 25, Issue 4 - Aug 1997
Volume 25, Issue 3 - Jun 1997
Volume 25, Issue 2 - Apr 1997
Volume 25, Issue 1 - Feb 1997
Selecting the target year
Numerical Analysis of Dynamic Stall of NACA0015 Airfoil
Ko, Sung-Ho ; Chung, Ju-Hyun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 1~1
A finite difference code has been developed and applied to numerical analysis of unsteady separating flows over an oscillating airfoil. The full as well as thin-layer Navier-Stokes equations have been solved with Spalart-Allmaras one-equation turbulence model. The time-marching integration of the governing equations by LU-SGS implicit scheme has been improved by using Matsuno's
. Numerical computations for three different unsteady flow conditions, corresponding to attached flows, light dynamic stall and deep dynamic stall, are compared with experimental data. The comparison reveals that the use of the full Navier-Stokes equations do not provide any advantages over that of the thin-layer Navier-Stokes equations when the simple Spalart-Allmaras one-equation turbulence model is used.
Application of Genetic Algorithm to Multi-Point Transonic Airfoil Design
Ahn, Jae-Kwon ; Lee, Dong-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 10~10
This paper presents a transonic airfoil design method based on a genetic algorithm coupled to a Euler solver. An airfoil shape was represented by base airfoil and shape functions selected using genetic algorithm. Airfoil which has maximum L/D at design point was designed by properly setting up objective function. The shape of airfoil that makes up a generation varies with the fitness value computed in the stage of previous generation, evolutes in the direction where fitness value increases. In this process, it was certified that the shape of the last generation also had a tendency to converge in same direction. Maximum thickness constraint was adopted as the airfoil shape constraint, and it was confirmed that maximum thickness constraint can be easily taken in consideration, imposed on the objective function as the penalty function. Two points design was performed to improve efficiency at off design condition, then the computation cost could be reduced by using the last generation at one point design as an intitial condition.
A Study on the Spanwise Blowing to Improve Aerodynamic Performance of a Wing with Simulated Ice
Lee, Bong-Joon ; Oh, Jae-Young ; Yoo, Sang-Sin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 16~16
The effect of a leading-edge simulated ice accretion on the aerodynamic performance of a wing with NACA 0012 airfoil was studied experimentally. Lift and drag characteristics were measured for the rectangular wing of AR = 4 with and without a leading-edge simulated ice in the wind tunnel. The experiment effort is directed towards developing the techniques of spanwise blowing to improve the aerodynamic performance of a wing with simulated ice on the leading edge. The experimental values have shown that the addition of simulated ice shapes on the leading edge causes a considerable reduction in
and lift-drag ratio, an increase in the drag values of 126-200% compared to the clean wing values. However, the aerodynamic characteristics of a wing with the leading-edge simulated ice with spanwise blowing to the leading edge showed an increase in
and lift-drag ratio.
Compressible Turbulent Flow around Airplane Wing Using LU factored Implicit TVD Scheme
Im, Ye-Hoon ; Chang, Geun-Sik ; Jeong, Hee-Gwon ; Kwon, Jang-Hyeok ; Park, Min-Woo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 26~26
A computer code incorporating a number of existing proper computational methods is developed to investigate the three-dimensional compressible turbulent flow around an aircraft wing. LU-factored implicit upwind TVD scheme is employed in which the Harten-Yee's modified upwind scheme is used far the explicit operator and the Steger-Warming splitting far the implicit part. Baldwin-Lomax turbulent model is adopted in this Computer Code. Flow past on NACA0012 airfoil and ONERA M6 wing are computed under three different conditions. The flow around the ONERA M6 wing showed that the results were in good agreement with the experimental data if the angle of attack was less than 5 degrees.
Numerical Simulation of Flow Structure and Heat Transfer in 3-D Turbulent Flows with Imbedded Longitudinal Vortex
Jeong, Jin-Yong ; Ryou, Hong-Sun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 36~36
Heat transfer characteristics and flow structure in turbulent flows through a flat plate 3-D turbulent BL containing built-in vortex generators have been analyzed by means of technique of Crank-Nicolson finite difference method. Under the slender flow approximation, the steady three-dimensional Navier-Stokes and energy equations are solved by C-N method. Longitudinal vortex in turbulent BLs belongs to the class of slender turbulent flow, in which velocity gradients in transverse direction are much larger than streamwise direction and the governing equations can be parabolized along this direction. The method is used space marching technique to economize on the computing time and the storage. This paper used the eddy diffusivity model and standard
model to predict heat transfer and flow field in the turbulent flow with imbedded longitudinal vortex. The results show boundary layer distortion due to vortices, such as strong spanwise flow divergence and boundary layer thinning. The heat transfer and skin friction show the relatively good results in comparison with experimental data. The vortex core moves slightly away from the wall and grows slowly; consequently the longitudinal vortices strongly perturb the velocity field of turbulent BLs and enhance the exchange of fluid between the well and the core region which causes high heat transfer augmentation over a very long distance downstream.
Sound Radiation from Elliptic Vortex Ring (II) : Mutual Threading Motion of Two Elliptic Vortex Rings
Ryu, Ki-Wahn ; Lee, Duck-Joo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 46~46
A vorticity field of the elliptic vortex filament in the low Mach number flow is generated when the configuration of the cold jet exit is elliptic shape. The leap-frogging motion, as it is sometimes called, is the 'mutual threading motion' is developed between two vortex rings, and affects the far field acoustic signals significantly. In this study, the far field acoustic signal is validated by comparisons with the analytic solution of circular vortex ring interaction. And after that, flow and far field acoustic calculations for two elliptic vortex rings are investigated numerically. Vortex motions and acoustic signals from two identical elliptic vortex rings, placed initially with selected separation distances, are calculated. The characteristics of the kinematic motions of two elliptic vortex rings is that two elliptic vortex rings have different eigenfrequencies: the first from the axis switching phenomena of elliptic vortex ring and the second from the leap-frogging phenomenon. The acoustic signals are accompanied with these characteristics. Especially, strong acoustic signals are generated at the instant of leap-frogging motion.
Analysis of Internal flow of Pressure Swirl Atomizer
Yoon, Seok-Ju ; Cho, Dae-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 56~56
A swirl atomizer is widely used in domestic and industrial combustion systems. The velocity profiles at the exit is one of the most significant factors to determine the spray characteristics. In this study, numerical analysis was carried out for the velocity field throughout a swirl spray nozzle, especially at the orifice. And effects of nozzle geometry which influence on the spray angle and the conical sheet thickness were investigated. The spray angle was predicted with the velocity profiles at the orifice. It is concluded that the geometrical properties of the nozzle are the most influential parameters to determine the flow characteristics and the predicted spray angles show good agreement to the measured ones.
A Numerical Study of Turbulent Reactive Flows using Turbulent Mixing PDE Models
Moon, Hee-Jang ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 67~67
Probabilistic mixing models based on probability density function approach for turbulent combustion are tested with the results of Direct Numerical Simulation. A model introduced by Dopazo and Valino which regroup the traditional LMSE(Least Mean Square Estimation) model and a stochastic process based on a binomial sampling is reviewed in detail. This study tries to emphasize the sensibility of the binomial model for a flow field subjected to a decaying homogeneous isotropic turbulent medium where the turbulence-chemistry intensity corresponds to a moderate
number. It has been demonstrated that the model follows quite well the simulation results and, when compares to LMSE model, binomial model enhances correct asymptotic gaussian behavior and gives a more realistic qualitative PDF evolution.
A Numerical Investigation of Shock-Enhanced Mixing and Combustion Process: Application to Circular Cross-Sectional Combustor
Lee, Sang-Hyeon ; Jeung, In-Seuck ; Yoon, Young-Bin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 78~78
A computational investigation of shock-enhanced mixing and combustion process applied to circular cross-sectional combustor is presented. Three-dimensional Navier-Stokes equations with a chemical reaction model and
turbulence model equations are used. It is shown that the mixing process has exclusive influences on the combustion process, whereas the combustion process does not have any significant effect on the mixing process. The combustion process is divided into two mixing regimes: a convection dominant regime, where burning rate increases, and a diffusion dominant regime, where burning rate is constant. In parametric studies, fuel density is a key parameter determining mixing and burning rate, whereas pressure or temperature makes little influence on mixing and combustion characteristics. In a circular cross-sectional combustor, there are shock wave intersection through the center axis. It is shown that the intersected shock waves have adverse effects such as reducing circulation and pushing fuel towards combustor wall.
Measurement of Mean Particle Sizes and Fuel Concentrations of the Sprays from a Centrifugal Two-Nozzle Injector by Light Integrating Diaphragm (LID) Method
Seol, Woo-Seok ; Yoon, Min-Soo ; Lee, Dae-Sung ; Yagodkin, V. I. ; Bae, Choong-Sik ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 95~95
Spray characteristics of a centrifugal two-nozzle injector were experimentally studied using the light integrating diaphragm method (LID) based on small angle laser light scattering. The theories on the small angle scattering were reviewed, which could be used to measure the size of liquid fuel droplets and the fuel concentrations. LID technique was successfully applied in one burner compartment in a test facility of gas turbine combustor. The measurement of Sauter mean diameter with LID method has an accuracy of about 5% for
liquid fuel droplets. Kerosene or water sprays from the dual swirl fuel nozzle were tested under various conditions in terms of the fuel supply pressure and air-assisting. It was found that the droplet size decreases as the injection pressure increases and more when the injection is assisted by air. The experimental results imply that the low pressure air-assisted injection can simulate the realistic high pressure injection.
Fuel Control Simulation of a Turbojet Engine Using a Prescribed Surge Margin
Boo, Joon-Hong ; Bae, Hak-Sung ; Kim, Jin-Gon ; Lee, Kang-Woong ; Kim, Jong-Sun ; Yoo, Sang-Sin ; Min, Seong-Ki ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 103~103
A theoretical method is presented to reduce the acceleration time while preventing a compressor surge fur a turbojet engine in which the fuel flow is the only control input. An appropriate surge margin for a corrected rpm value is prescribed based on a compressor performance map of a specific engine, and the surge margin is kept below the specified value during acceleration. The fuel flow that causes the pressure ratio to approach the surge control line was calulated based on the dynamic and thermodynamic balance equations, and the performance map of the engine. Also, the relation between the changes in pressure ratio and fuel flow rate was calculated using differential increase of fuel flow at a steady state of the same corrected rpm. The proposed method was compared with a case where the fuel is increased as a step change without any control method, and with a case where fuel flow is accelerated based on balanced conditions at steady states. The calculation was conducted via a computer program that can simulate the transient performance of the engine, and primary performance variables such as compressor pressure ratio and turbine exit temperature were calculated as functions of time, along with fuel flow, and corrected rpm.
Dynamic Analyses on Thermo - Elasto - Viscoplasticity of Composite Materials Using Finite Element Method
Shin, Eui-Sup ; Kim, Seung-Jo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 112~112
A series of thermoviscoplastic analysis is performed to view the thermomechanical effect for composite materials subject to dynamic periodic loading. An extended unmixing-mixing scheme is utilized to describe the orthotropic thermo - elasto - viscoplastic characteristics of composite materials. The equation of motion and the energy conservation equation based on the fully-coupled thermodynamics are considered with the auxiliary initial and boundary conditions. Then, the governing equations are reformulated with the finite element method, and then the time marching techniques are applied. The derived nonlinear equations are iteratively solved with efficient computational algorithms. Finally, a set of numerical examples are presented to show the fundamental trends of the dynamic behavior of composite laminates.
Static Structural Test and Analysis of Basic Trainer
Hwang, Cheol-Ho ; Park, Chan-Ik ; Hah, Seung-Rong ; Kim, Chang-Wan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 123~123
There are several specifications which specify the requirement for strength and the procedures for the airframe strength substantiation. Structural tests and stress analysis should be peformed to prove the static safety of airframe. For the substantiation of a basic trainer, stress analysis for the whole airframe elements and full scale static test were performed by the procedure specified in MIL-SPECs and FAR 23. In this paper, the results of analysis and test were compared. Through agreement of both results, the static safety of the airframe is confirmed in the envelope of the flight and ground operation of design criteria.
A Semi-Analytical Solution of the Attitude Motion of a Satellite during Spinning Injection Mode
Kang, Ja-Young ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 131~131
The attitude stability of a communication satellite in spin-stabilized injection mode which contains a liquid pool is investigated. The satellite model far this investigation is a two-body system consisting of a main body, which is symmetric and rigid, representing the spacecraft, and a spherical pendulum, representing the liquid pool. Assuming that both spacecraft and pendulum are in states of steady spin about the symmetry axis of the spacecraft, the coupled nonlinear equations of motion fur the system are simplified. In this paper, by using the multiple scales method, the possible resonance conditions in terms of the system parameters are determined and the corresponding near-resonant solutions are derived to observe how the resonant motion develops.
Modified Extended Kalman Filter Technique for Car Navigation in Urban Environment with Limited GPS Visibility
Won, Jong-Hoon ; Lee, Ja-Seong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 139~139
This paper presents a modified GPS Kalman later algorithm which is ideally suited to car navigation in urban areas where lack of GPS visibility is the major problem because of the frequent blockage of the GPS signals by tall buildings and other structures. The method allows the user to estimate its position when the number of visible GPS satellites becomes less than four by using fixed altitude estimation and clock bias estimation techniques. The two estimation techniques are related to the Kalman filter in a mutually compensating manner that it is shown the 3-dimensional position accuracy can be well maintained when the number of the visible satellites drops down to two fer a reasonable period of time. Simulation results are included to show the improved performance of the modified Kalman filter algorithm over a normal GPS Kalman filter.
Study on the three-axes attitude controller design of Satellite using reaction wheel
Woo, Byoung-Sam ; Jung, Bo-Hwan ; Chae, Jang-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 148~148
Attitude controller of small satellite was designed in this paper. Four reaction wheels give a control torque to the satellite. At first, the design of wheel speed controller was performed by using linear model and then it was considered that each nonlinear effect to this system by inserting nonlinearity. The design purpose of wheel speed controller is that the outputs(wheel angular velocity or wheel angular momentum) show the fast response to the desired momentum. The PI controller was used in order to get the fast response speed without overshoot. Three-axis attitude control was performed by using precede reaction wheel model after completing wheel speed controller. Reaction wheels have a 'pyramid' configuration which all four wheels are skewed and one wheel is a redundancy. Same as the wheel speed controller, PI controller was used and designed to coincident with the given bandwidth of the satellite. If the inputs that compensate the attitude error due to the external disturbances or perform the mission of the satellite are given to the attitude controller, it can be acquired that attitude error, wheel angular momentum, angular velocity of the satellite, and etc.
A Study of Baldwin-Lomax Model in Supersonic Flows
Baek, Seung-Woock ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 157~157
Research trend in smart structures based upon fiber optic sensors
Park, Jung-Wan ; Hong, Chang-Sun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 163~163
Research Trend in Vibration Control of Smart Structures Using Piezoelectric Materials
Lee, In ; Han, Jae-Hung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 168~168
Smart Structural Systems Utilizing ER Fluids
Choi, Seung-Bok ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 3, 1997, Pages 177~177