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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 26, Issue 3 - May 1998
Volume 26, Issue 1 - Feb 1998
Volume 26, Issue 8 - 00 1998
Volume 26, Issue 7 - 00 1998
Volume 26, Issue 6 - 00 1998
Volume 26, Issue 5 - 00 1998
Volume 26, Issue 4 - 00 1998
Volume 26, Issue 2 - 00 1998
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Verification Study of the Random Vortex Method on Two-Dimensional Steady & Unsteady Flowfield
Park, Jin-Ho ; Lee, Duck-Joo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 1~1
Random Vortex Method, simulating the vortex dominant viscous flowfields via discrete vortex particles is improved in the accuracy by rectifying numerical algorithm and selecting the numerical parameters carefully. Test of the improved method is accomplished through applying to laminar boundary layer by using the incompressible, two-dimensional Navier-Stokes equations, and to the viscous diffusion problem. Verification of the modified method on unsteady flow is made by applying to the diffusion equation and the problem of an impulsively starting circular cylinder. For the problem of an impulsively starting circular cylinder, vortex structure including
phenomena are clearly captured for Reynolds numbers of 550, 3000 and 9500, respectively. Excellent agreement with experiments are achieved of flow patterns and velocity for the wide range of Reynolds numbers. Critical improvements in the method is in the algorithms for higher order time integration, the selection of vortex particle size, and the treatment of vortex particle near the wall.
Analyses of the Normal Shock Waves in the Rarefied Gas Regime with Dissociation
Lee, Dong-Dae ; Park, Hyung-Koo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 11~11
In this study, we examined the thickness and 3-mode temperature distributions of normal shock waves with various Mach numbers and densities, considering translational, rotational and vibrational modes by using DSMC, which is a most useful numerical method in rarefied gas regime. As the shock became stronger, the thickness was reduced. On the other hand as the shock became weaker, there was a significant increase in the thickness. Also, in the case of high Mach number there can be seen an overshoot of translational temperature near the shock center. To examine the effects of dissociation in the reentry region we sieved a strong shock wave problem with Ma=20, where the vibrational energy can be greater than the dissociation energy. The techniques used in this paper can be utilized for the cases of reentry vehicles with minor modifications.
A Study on the Aerodynamic Characteristics of a High Speed Train Entering a Tunnel and Frontal Shape Optimization
Kim, In-Sun ; Ok, Ho-Nam ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 17~17
As a part of the research to develop an optimum frontal shape of a high speed train, a prediction method of the wavefront of a compression wave generated by a train entering a tunnel with a steady state solution, is applied to 9 systematic nose shapes and TGV-K nose shape. Also the concept of area rule, which has been used for the design of a transonic aircraft, was investigated to see if it is applicable to the design of a high-speed train nose. As a result, a wedge-like nose shape with small variation of cross-sectional area and long nose, was found to have the best wave characteristics during tunnel entrance.
Parallel Processing for an Euler Code Using Unstructured Grids
Kim, Sung-Ho ; Kwon, Jang-Hyuk ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 27~27
In this paper, a new computing environment, so called 'Parallel Computing' is adopted to get the numerical results of CFD problems. To apply the traditional CFD algorithm into the parallel computer, the domain decomposition technique compiler dependent technique and PVM message passing library are used. By distributing computing loads, we can get reasonable computing time to solve CFD problems with the unstructured grids. As a result, the possibility of massive usage of parallel computers in near future is demonstrated.
Heat/mass transfer characteristics around film cooling hole with compound angle orientations
Cho, Hyeong-Hui ; Kim, Byeong-Gi ; Rhee, Dong-Ho ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 35~35
Experiments are performed to investigate the detailed heat/mass transfer coefficients for injections through a single film cooling hole. The hole is inclined in compound angle orientations which are
in streamwise direction and from
in spanwise direction. A naphthalene sublimation technique has been employed to determine the local heat/mass transfer coefficients near the injection holes. Results indicate that Sherwood numbers around the injection holes are up to four times those on a flat plate flow without injection holes. The heat/mass transfer around the injection holes is dominated by formations of horseshoe-, side-, ring- and kidney-vortices which are generated by the jet and cross-flow interaction. The injected jets spread more widely with the compound angle injections than the axial injection. The heat transfer coefficients increase and have more uniform values as the lateral angle increases from
(axial injection) to
(lateral injection). The mass transfer around the injection hole is significantly influenced by blowing rates. The injected jet penetrates into the main stream at the high blowing rates while the jet is suppressed by the main stream and spreads on the surface at the low blowing rates. Surface flow visualization indicates that the influence area by jet injection increases with the lateral angles and the blowing rates. This results match qualitatively well with the mass transfer results.
A study on the characteristics of spray pattern by two-fluid Swirl injector
Cha, Yeong-Ran ; Joung, Rae-Hyeok ; Kim, Yu ; Min, Seong-Gi ; Kim, Yeong-Yeon ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 45~45
An experimental study was carried out to investigate the effect of water pressure (
) and air pressure (
) to the discharge coefficient, dispersion angle of a liquid sheet and mass distribution for two-fluid swirl injector. Measured discharge coefficient was 0.24 and supplied air had little effect on it. Instantaneous images of the spray were taken by the stroboscope and camera and from these images, dispersion angle was measured. Dispersion angle showed to be decreased from 88 to 80 degree with increasing supplied water pressure. Mass distribution was measured by the patternater. The maximum value of mass distribution was shifted to the outside and tend to evenly distribute compare to no air supply. This phenomenon were more clearly obeserved with increasing air pressure.
Numerical Investigation of Flows in a 90-Degree T-Branch of Square Cross-Section
Kim, Young-Mog ; Son, Ho-Jae ; Oh, Seung-Hyub ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 52~52
Numerical investigations of three-dimensional laminar flows in a 90-degree T-branch of square cross-section were carried out to acquire an understanding of the effect of inlet Reynolds numbers and branch to main flow rate ratios on flowfields and local pressure variations along a main duct, by solving the incompressible Navier-Stokes equations in generalized curvilinear coordinates. Computation for a two-dimensional bifurcation flow was in excellent agreement with experimental measurements available in the literature for streamwise velocity profiles in the main duct. In this study, numerical calculations were performed for various Reynolds numbers and branch to main flow rate ratios of 0.2, 0.5, and 0.8. The computed results showed that branch flow induced adverse pressure gradient and flow separation on the main duct, which was observed to be changed depending on the Reynolds numbers and branch to main flow rate ratios. In addition, effect of branch flow rate ratios on streamwise vortices downstream of a branch region was discussed in detail.
Effects of Flexibility of Flight Control System and Structural Deformation of Wing on Aileron Design
Lee, Seung-Soo ; Kim, Myung-Seong ; Kim, Byung-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 64~64
The effects of the flexibility of flight control system(FCS) and the wing twist on the design of an aileron have been studied. The mathematical model which can predict the adverse effect of the flexibility of FCS on the steady state roll rate and the linear method which can estimate quantitatively the effect of wing twist on roll performance have been proposed. The flight test results of an turbo-prop trainer are compared with the estimation by the proposed methods. The adverse effects of the wing twist on roll performance were also discussed with the flight test results.
Signal Characteristics in the Delaminated Composite Specimen with Fiber Optic Sensor
Park, Jung-Wan ; Kyung, U-Min ; Ryu, Chi-Yeong ; Kang, Hyeon-Gyu ; Hong, Chang-Seon ; Kim, Cheon-Gon ; Jeon, Seung-Mun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 70~70
Delamination problems are one of the most important issues affecting the applications of composite laminates. Delamination reduces overall structural performance of composite laminates such as stiffness, strength, and buckling load. Therefore, it is necessary to identify the influence of delamination failure on composite laminates. The delaminated unidirectional composite specimens subjected to the compressive load were tested to study the characteristics of fiber optic sensor (FOS) signals when the buckling and the growth of delamination occurred. Extrinsic Fabry-Perot interferometers (EFPI) were used in this study. EFPI was embedded in the delaminated composite specimen or attached on the surface of specimen. As the specimens were buckled, the signals of FOS were analyzed. And also when the delamination growth occurred, the characteristics of FOS signal and data aliasing caused by the sampling time were investigated. The effects of the delamination length were discussed.
Outgassing Characteristics of Composite Materials under Vacuum Environment
Shin, Gwang-Bok ; Kim, Cheon-Gon ; Kim, Byeong-Gyo ; Kim, Hak-Jeong ; Lee, Ho-Hyeong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 79~79
In order to study the outgassing characteristics of composite materials in space, T300/AD6005 graphite/epoxy laminate specimens were exposed to high vacuum and high temperature in the thermal-vacuum chamber. The pressure in the chamber was
Torr, and the temperatures were
. The outgassed product of T300/AD6005 graphite/epoxy laminate specimens were analyzed with a QMS(quadrupole mass spectrometer). The outgassing rate of the composite laminate specimens were evaluated using the pressure-rise method, by which the pressure-rise in the chamber was monitored when the vacuum valve was closed. The results showed that the vacuum in space reduced the mass of T300/AD6005 graphite/epoxy composite materials, and the outgassing rate increased with the temperature.
Transient Thermal Stresses in a Hollow Circular Cylinder of a Functionally Graded material
Kim, Kui-Seob ; Choi, Deok-Kee ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 89~89
We treat the transient temperature distributions and thermal stresses in a hollow circular cylinder of the functionally graded materials (FGM). Nonhomogeneous materials such as FGM have special characteristics due to arbitrarily distributed and continuously varied material properties. For such nonhomogeneous materials, the heat conduction equation is presented in a nonlinear farm. A typical method solving the problem is to use the Laplace transformation. However it becomes difficult to carry out the inverse Laplace transformation to obtain the solution when the functions of the materials properties are given in terms of the high-order polynomials. In this study, a modified Green's function is introduced to solve the nonlinear heat conduction equations. The aim of this study is to understand the effect of the composition on thermal stresses under the heating and cooling conditions.
Orbit Determination Simulations for the KOMPSAT Spacecraft Using On-Board GPS Navigation Solutions and Single Ground Station Tracking Data
Lee, Byoung-Sun ; Lee, Jeong-Sook ; Kim, Yoon-Ki ; Eun, Jong-Won ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 99~99
The orbit determination simulations for the KOMPSAT spacecraft were performed using two types of tracking data. One was on-board GPS navigation solutions and the other was single station ground-based tracking data. GPS navigation solutions that were included in telemetry streams were assumed to be transmitted from the KOMPSAT satellite every 32 seconds interval. GPS navigation solutions include position and velocity vector fer each time steps. Ground-based tracking data set was selected from the combinations of azimuth/elevation, range, and range rate data. Minimum variance technique was applied for estimating position and velocity of the satellite. Orbit determination errors were estimated during the batch process when only random measurement noise was assumed. A priori semi-major axis was biased from the known values and the final orbit determination state was compared with propagated states.
Automated Aircraft Flight Control Design Using Parameter Optimization Techniques
Ryu, Hyeok ; Tahk, Min-Je ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 111~111
Automated controller parameter extraction technique for an classical-type controller is presented in this paper. Control design problem is formulated as parameter optimization problem, and optimal solutions are calculated by parameter optimization solver, hybridization of evolutionary programming and sequential quadratic programming. We applied this technique to a phase lead/lag compensator design and an aircraft flight control design problem, and obtained controller parameters satisfying design specifications.
Development of PC based Engineering Flight Simulator
Kim, Joung-Uk ; Ko, Sang-Ho ; Ko, Jin-Young ; Jong, Il-Young ; Lee, Gi-Beom ; Oh, Tae-Shik ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 120~120
Most of the high performance aircraft currently under development are aimed for achieving excellent aerodynamic performance and maneuverability. High fidelity six degree-of-freedom (6-DOF) simulation is required fer the design of optimum aerodynamic configurations and Fly-By-Wire flight control system. In order to build-up the 6-DOF simulation technology, the engineering simulator was developed by constructing simulation database systematically and developing real time simulation software which can be generally used for aircraft development. The fixed-base engineering simulator consists of PC and DSP board and it is currently used as an essential design tool for control law design and verification by flight control group.
A study on spray and combustion efficiency of unlike triplet impinging injector for liquid rocket engines
Chung, Yong-Gahp ; Kim, Seon-Jin ; Jee, Pyung-Sahm ; Kim, Seon-Gee ; Kim, Yoo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 129~129
An experimental investigation by nonreactive and hot-fire tests has been carried out to examine the spraying phenomena and combustion performance of unlike triplet impinging injector. In nonreactive (cold-flow) tests, spray angle, breakup-frequency, mass distribution and mixing efficiency were measured and in hot-fire tests, the combustion performance for O/F ratio was studied. From hot-fire tests, the O/F ratio 3.9 for uni-element rocket engine using
, Kerosene and an unlike triplet impinging injector is recommended by the optimum value.
Unsteady Analysis of Ignition Phenomena in the Pulse Combustor with Counter Jet Flows and NOx Emission Characteristics
Lee, Chang-Jin ; Kim, Sung-In ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 137~137
An analytical study has been carried out to investigate the unsteady ignition characteristics of pulse combustion. In the pulse combustion, two jets(hot burnt gases and fresh mixtures) coming from the opposite side of the combustor collides in the combustor forming a stagnation region where the chemical reactions are suppressed by the strain rates until it becomes below the critical value. In this research, the method of large activation energy asymptotic was adopted with one step irreversible kinetics to examine the ignition response to the variation of the strain rate of flow. Also, the strain rates of the flow were modelled by the two separate contributions: the mean strain rate by the bulk flow and the turbulent induced strain rate. The NOx emission characteristics was studied experimentally as well according to the variation of the mean strain rate by the unsteady jet flows. The results show there exists a well-defined ignition delay. And the variation of the maximum value of strain rate that is proportional to the inverse of the Damkohler number can mainly determine whether the ignition or extinction occurs. The amount of NOx was profoundly influenced by the strength of the jet flows in the combustor.
Measurement of Solid Propellant Combustion Response Functions for Rocket Motor Combustion Instability Analysis
Park, Young-Kyu ; Yoo, Ji-Chang ; Kim, In-Chul ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 149~149
Combustion response functions fer the linear stability analysis in a solid rocket motor was measured using a T-burner fur 4 kinds of composite and double base solid propellants. Pulsed DB/AB method was used for the measurements in the range of pressure oscillation of
. The results were compared with the values from a theoretical model(AB model). As a results, the relationship between combustion response functions and pressure oscillation frequencies was obtained. Also, it was confirmed that AB model was suitable far description of the combustion response behavior of propellant having homogeneous burning surface. It seems that additional measurements are needed for more accurate analysis. On the other hand, it would be a good alternative to use the AB model for the case of the high frequency transverse mode instability.
The Design and Development of Filament Wound Composite Fuel Tank for Aircraft
Park, Dong-Chang ; Cho, Byeong-Gyu ; Kim, Gwang-Su ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 156~156
This paper is part of a series on the subject of composite external fuel tank developed for the aircraft. Part I will introduce the series and will cover the product requirements, structural design, stress analysis, and certification testing. Part II will cover the material, processing, and manufacturing. The composite fuel tank was designed far high performance aircraft, using a filament winding technology with integral rubber liner and lightning strike protection. The filament winding technology combines honeycomb sandwich structure taking full advantage of high strength/stiffness-to-weight ratio, high impact resistance, and explosion containment capability. The baseline design was performed using basic strength analysis together with finite element analysis. The developed fuel tank was found to substantially exceed specification requirements while maintaining light weight and competitive manufacturing cost.
IMF Era and Korea's Aerospace Industry
Lee, Seung-Ri ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 26, issue 1, 1998, Pages 167~167