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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
Journal Basic Information
Journal DOI :
The Korean Society for Aeronautical & Space Sciences
Editor in Chief :
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
Calibration of the Aeroacoustie Wind Tunnel and the Experimental Techniques for Scaled Models
Choi, Jong-Soo ; Park, Kyu-Cheol ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 1~1
Aeroacoustic wind tunnels are being used for the experimental investigations of the generation, transmission and radiation of sound from the noise sources such as airfoils, turbomachinery and helicopter rotors. The aerodynamic and acoustic performance of the tunnels are hevily dependent on the performance of individual tunnel components which needs to be well predicted at the design stage. The purpose of this research was to evaluate the performance of the recently completed aeroacoustic wind tunnel of Chungnam National University in order to verify the design criterions used and to find the limitations of the usage. Test result shows that the tunnel background noise level is low enough for the measurements of the relatively weak sound radiated from an isolated circular cylinder placed in a uniform flow. It is also shown that the acoustic similarities can be applied to the results of scaled model testing given that the flow conditions are similar.
Comparison of the Rotor Wake Modeling in Hovering Motion
Ryu, Ki-Wahn ; Na, Sun-Uk ; Lee, Duck-Joo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 11~11
The time marching free wake model of the helicopter rotor in hovering motion is compared with the prescribed wake model. The flows are assummed to three-dimensional unsteady potential flow. In prescribed wake method, an empirical formula from experimental results is used to calculate the wake geometry until the computed thrust coefficient is well agreed with the given thrust value. However, in free wake method the wake shed from the trailing edge of the rotor blade makes the global wake geometry without any particular restriction. For the case of the single blade rotor in hover, the thrust and lift distribution along the span are obtained and the radial and axial wake geometries that is, the inner vortex sheet and the tip vortex line are calculated. The numerical results are in good agreement with the results obtained from the prescribed wake geometry. The computed free wake geometry is also at least qualitatively in good agreement with the experimental wake geometry which is represented by three wake region;
revolutions of well defined tip vortex lines, recirculated and expanded zones of far wakes.
Inviscid Dynamic Characteristics of Rotordynamic Forces due to Asymmetric Tip Clearance-Off Design Effects
Song, Seung-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 21~21
An actuator disc analysis has been carried out to examine the effects of off-design turbine operation on the dynamic characteristics of inviscid rotor dynamic forces due to asymmetric tip clearance distribution. Azimuthal flow redistribution (e.g. velocity and pressure distribution) is calculated as a function of whirl speed, and, thus, direct and cross stiffness forces are obtained. From the slope of the cross stiffness force, direct damping coefficient is obtained. The analysis results predict that, as the flow coefficient increases, turbine blade loading decreases. Consequently, both cross stiffness coefficient and direct damping coefficient decrease.
Numerical Study of the Chemically Reacting Flows in the Solid Fuel Ramjet Engine Combustor
Kim, Sang-Soo ; Baek, Seung-Wook ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 30~30
Numerical code to analyze chemically reacting flows in the solid fuel ramjet engine combustor has been developed. LU-SSOR implicit scheme with finite volume method is used to solve the Navier-Stokes equations fully coupled with the chemical species continuity equations. Polyethylene is used as solid fuel and chemical reactions are modeled by a 6 species, 2-step finite chemistry. The turbulence is treated by the Baldwin-Lomax algebraic model. To verify this numerical code, axisymmetric compressible flows in the JPL nozzle and chemically reacting flows over 2-D compression ramped duct are solved. After code verification, the variations of chemically reacting flows in the solid fuel ramjet combustor, mean solid fuel regression rate and thrust for the inflow conditions and combustor geometries are investigated.
The Effect of Fe Compounds for Burning Catalyst on HTPB/AP Propellant
Hwang, Kab-Sung ; Yim, Yoo-Jin ; Kim, Chang-Kee ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 39~39
A study on three catalysts for burning rate enhancement has been carried out by considering burning rate, mechanical properties, and processibility in the HTPB/AP solid propellant. The selected catalysts were Butacene grafted by silicone-ferrocene in HTPB, acylaziridinyl ferrocene (AAF), and superfine iron oxide(SFIO) which was 3nm in diameter. In the case that AAF or SFIO were added in propellant, the pot life of HTPB propellant was drastically decreased, but Butacene propellant showed high end-of-mix viscosity and low viscosity build-up curve. It was found that the mechanical properties of HTPB propellant have been worse by addition of Butacene or AAF except SFIO. The order of efficiency of burning catalyst was proved to be AAF>SFIO>Butacene as based on catalyst content and AAF>Butacene>SFIO as based on Fe content in propellant due to the different reaction rate of each flame in HTPB/AP propellant combustion.
A Study on the Spray Characteristics of the Swirl Type Injector
Park, Byeong-Seong ; Kim, Sun-Jin ; Kang, Kyeong-Taek ; Kim, Yoo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 49~49
An experimental study was carried out to invesigate the spray characteristics of the swirl injector to determine the effects of the geometric design parameters and pressure drop on the air-core diameter in the post, mass distribution and SMD. The geometric parameters were post length to diameter ratio(post L/D) and water was a simulant far the cold test. One dimensional PDPA was used to measure air-core diameter, drop velocity and SMD. Followings are the results of this study. 1) Air-core diameter increased for the pressure drop up to
effect of pressure drop was negligible. 2) With increasing pressure drop, dispersion angle increased and SMD decreased, therefore show good atomization characteristics. 3) Dispersion angle increased with decreasing post L/D.
Experimental Investigation of Turbomachinery Blade Tip Leading
Yoo, Il-Soo ; Song, Seong-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 55~55
This paper presents results from an experimental study on tip leakage flows in axial turbines. Turbine casing wall rotation has been simulated by using a moving-belt tip wall. Static pressure measurements were made on an isolated turbine blade far clearance sizes of 3mm(
), and 10mm(
). Three wall speeds were considered in addition to the case of no rotation. The tip loading increases as the tip clearance is enlarged. A significant reduction in the tip loading due to the relative motion is also absolved. Furthermore, the effect of unloading decreases as the tip clearance is increased. Finally, it is hypothesized that such tip loading behavior is closely coupled to the strength of tip vortex.
Analysis of Member Length Effect on Concept Joint Models
Lee, Kwang-Ju ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 63~63
The concept models of joints are used in the analysis of structures because they are more economical and practical than the detailed models. The concept joint models usually use torsional springs. The magnitudes, positions, and orientations of torsional springs can be used as parameters in order to account for the flexibility, locations of rotation centers, and coupling effect of joints, respectively. The modeling parameters of a joint are usually identified using the results of experiments performed on a substructure which contains a joint itself and the attached members. However, the estimates of parameters may have different values when the length of attached members changes. It is due to the fact that the magnitude of shear deformation changes with the length of members. The effect of member length on parameters of concept joint models is investigated. The investigation was applied to a T-shaped joint made of simple box beams and to a joint in a real vehicle structure.
A Study on the Structural Behavior for the Design of the Small Aircraft Composite Propeller Blade by Considering Bird Strike Impact
Kong, Chang-Duk ; Lee, Joung-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 72~72
The development of aircraft composite propeller is necessarily required because recently changing metal propeller to composite propeller is a global tendency due to the improvement of composite manufacture technique and good characteristics of composite materials. The composite propeller blade must be safely designed about static and dynamic loads. The structural stability of composite propeller blades in this study was analyzed by the Finite Element Method. When the static load was acted on the composite propeller, linear and nonlinear analysis was performed with the three different types of blade structure. In order to analyze the problem of the dynamic impact load acted on the blade of shell-spar-foam structure by bird strike, Newmark method was used for linear direct transient analysis. And the Campbell diagram was drawn as the result of eigenvalue problem analysis about the composite propeller. The Natural frequencies of the shell-spar-foam blade were compared with the forced frequencies by engine rotational speed and it was found that the resonance phenomenon did not occurr in the blade. The results of the above structural analysis will be used as technical data fer the design optimization of composite propeller blade.
Dynamic Stability of Free-Free Timoshenko Beam Subjected to Pulsating Follower Force
Choo, Youn-Sun ; Kim, Ji-Hwan ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 86~86
The dynamic stability of free-free Timoshenko beam subjected to pulsating follower force
such as missile or rocket is analyzed in this paper. Equation of motion is obtained by finite element method and then the method of multiple scales is used to investigate the dynamic instability region. It is assumed that the beam has concentrated mass. The effects of the axial location and the translation inertia of concentrated mass are studied. And the change of combination resonance type due to
magnitude, the relationship between critical force type and width of instability region in the vicinity of
and the effect of shear deformation are also investigated.
Terminal Guidance Algorithms of Missiles Maneuvering in the Vertical Plane
Kim, Eul-Gon ; Cho, Hang-Ju ; Lee, Yong-In ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 97~97
This paper presents real-time onboard terminal guidance algorithms of anti-tank and anti-ship missiles with constrained flight path angle at impact. Presupposing that targets are stationary or slowly moving compared with the missile, missile motion is described by a point mass second order kinematic equations in the vertical plane. The linear dynamic model is followed by application of linear quadratic optimization techniques considering soft and hard terminal boundary conditions. Two performance indices are considered; One consists of terminal miss distance and control efforts along the whole range, the other terminal miss distance and a linear combinations of overall control efforts and flight heights. Generally, the former gives rise to Pop-up/Dive height profile, the latter so-called Vertical Bunt height profile showing in the final stage of missile's trajectory a sharp rise followed by sharp fell to the target. Exploiting acceleration command profile obtained from a closed form solution, minimum range to begin the terminal guidance mode has been calculated. To substantiate our conclusion, results of the 6-D.O.F. simulation have been illustrated.
Study on Digital Flight Control System Design using Parameter Optimization
Ha, Cheol-Keun ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 104~104
Recently, there is a great demand that a practically applicable technology be developed to design in microprocessor digital flight control systems with better performance. This paper proposes an optimization method of designing digital control systems using output feedback. This method is based on definition of
in which optimal digital control system is designed in
rather than in discrete-domain. Furthermore, this method has the design capability to handle special structures of digital controller with low-order. Basic concept of this method is to take advantage of utilizing the optimization algorithm based on gradient search in which optimal analog controller with low-order can be designed. To accomplish this concept, internal stability is defined in
, and discrete system in state space, structured digital controller with arbitrary order, and performance index are also defined in its 'ficticious' time-domain. The most important is that 'Gain Transformation' is formulated to realize the digital controller equivalent to that originally designed in
, and used to design without nonlinear constrainst optimal digital controllers with low-order. As a simple design example, a longitudinal stability augmentation system (SAS) for B767 airplane is designed to verify the method to be valid and to show applicability to practical design of flight control systems.
On the Attitude Control of a Satellite with Incomplete Set of Reaction Wheels
Hwang, Jai-Hyuk ; Lee, Seong-Choon ; Oh, Hwa-Suk ; Eun, Jong-Won ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 114~114
Attitude control of a satellite is the process of orienting the satellite in a specified, predetermined direction. It consists of attitude stabilization and attitude maneuver control. In this study, when a part of actuators of the satellite becomes out of order, an alternative control algorithm has been suggested using the remaining actuators as a backup means. When two of four reaction wheels of the satellite fail, the alternative control algorithm for attitude control depends on the positions of the failed reaction wheels. When the failed wheels are placed opposite to each other, it is possible to control the attitude of the satellite using the only remaining two reaction wheels. However, when they are placed adjacent to each other, the attitude control would still be possible using the proper combination of the remaining wheels and dissimilar actuators. It has been found by a series of simulation that the currently suggested control algorithm would be successful in controlling the attitude of the satellite with defective reaction wheels.
Roll/Yaw Feedback Control Law Design for a Pitch Bias Momentum Spacecraft: Open-Loop Approach
Bang, Hyo-Choong ; Park, Young-Woong ; Nam, Moon-Gyung ; HwangBo, Han ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 123~123
An open-loop control technique far the roll/yaw attitude control of a pitch bias momentum spacecraft is presented in this paper. The control law is based upon the gyroscopic roll/yaw dynamics, which is due to a pitch bias momentum wheel. It is assumed that spacecraft body-fixed thrusters are used to produce control torques. The control law design consists of two separate stages. In the first stage, the initial notational motion is stabilized while pointing maneuver is achieved during the second stage of control action. Thruster magnitude limitation is also taken into account which results in a series of impulsive inputs. The new control law is open-loop type and easy to implement.
Fuel Optimal, Multi-impulse Orbit Rendezvous Between Neighboring Orbits
No, Tae-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 133~133
The linearized orbit dynamics and a direct, numerical minimization technique were used to solve the rendezvous problems between neighboring orbits. The possible existence of N-1 optimal solution could be guessed from the N impulse minimum solution, and optimality of the solution was post-analyzed by showing that the solution satisfies the necessary conditions which are based on Lawden's Primer vector. Some of the previously solved problems are revisited to verify the correctness and simplicity of the current approach and its future applicabilities are suggested.
Dynamic Behavior of Aircraft Landing Gear with Typical Dual-Chamber Shock-Absorbers
Hong, Nie ; Lim, Kyeong-Ho ; Hwang, Jae-Hyeok ; Kim, Du-Man ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 142~142
In this paper dynamic analysis of aircraft landing gear during landing impact and taxiing with typical dual-chamber shock absorbers are conducted. A simplified model for the dynamic analysis is developed by assuming a three-masses system, i.e. sprung, unspurng and rotating masses. Kinematic equations are given, in which stroke, stroke velocity, tire deflection, the slip velocity between the tire surface and the ground are considered. Force relations are discussed dealt with internal shock shrut force, hydraulic force, bearing friction, tire vertical reaction and tire drag force fer single dual-chamber shock absorber. The analytical results for the three typical types of shock-absorber are obtained under design impact and taxiing conditions. Some main characteristics describing dynamic behavior of dual-chamber shock-absorbers, such as, overlaod, unsprung displacement, absorbed energy and tire deflection are presented. It demonstrates that there are respectively advantages and disadvantages for different types of dual-chamber shock absorbers, which is helpful far aircraft landing gear design.
Identification and Numerical Optimization for Finalizing Multistage Axial Flow Compressor Design
Park, Ki-Cheol ; Kim, Seung-Woo ; Lim, Jin-Shik ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 153~153
A design refinement scheme composed of identification and optimization for freezing multistage axial-flow compressor's geometry has been developed. By applying this scheme to 4-stage experimental compressor's design, the adiabatic efficiency was increased about 4.4% than that of the first prototype compressor. So, this scheme can be used for design refinement of multi-stage axial-flow compressor when the performance test result of a prototype compressor does not satisfy design requirement.
Development Activities of Multipurpose Unmanned Helicopter at DAEWOO
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 162~162
Helicopter Developments in Korean Air - Current Status & Perspectives -
Lee, Sang-Chul ; Kim, Young-Kook ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 170~170
Introduction to Halla Aerospace
Yun, Hyo-Chul ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 175~175
Space Science in Japan - Organization, Achievements, and Prospects -
Nishida, A. ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 25, issue 4, 1997, Pages 177~177