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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 37, Issue 12 - Dec 2009
Volume 37, Issue 11 - Nov 2009
Volume 37, Issue 10 - Oct 2009
Volume 37, Issue 9 - Sep 2009
Volume 37, Issue 8 - Aug 2009
Volume 37, Issue 7 - Jul 2009
Volume 37, Issue 6 - Jun 2009
Volume 37, Issue 5 - May 2009
Volume 37, Issue 4 - Apr 2009
Volume 37, Issue 3 - Mar 2009
Volume 37, Issue 2 - Feb 2009
Volume 37, Issue 1 - Jan 2009
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Aerodynamic Simulation of Rotor-Airframe Interaction by the Momentum Source Method
Kim, Young-Hwa ; Park, Seung-O ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 113~120
DOI : 10.5139/JKSAS.2009.37.2.113
To numerically simulate aerodynamics of rotor-airframe interaction in a rigorous manner, we need to solve the Navier-Stokes system for a rotor-airframe combination in a single computational domain. This imposes a computational burden since rotating blades and a stationary body have to be simultaneously dealt with. An efficient alternative is a momentum source method in which the action of rotor is approximated as momentum source in a stationary mesh system built around the airframe. This makes the simulation much easier. The magnitude of the momentum source is usually evaluated by the blade element theory, which often results in a poor accuracy. In the present work, we evaluate the momentum source from the simulation data by using the Navier-Stokes equations only for a rotor system. Using this data, we simulated the time-averaged steady rotor-airfame interaction and developed the unsteady rotor-airframe interaction. Computations were carried out for the simplified rotor-airframe model (the Georgia Tech configuration) and the results were compared with experimental data. The results were in good agreement with experimental data, suggesting that the present approach is a usefull method for rotor-airframe interaction analysis.
An Unsteady Numerical Method of Autorotation and the Effect of 2D Aerodynamic Coefficients
Kim, Hak-Yoon ; Sheen, Dong-Jin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 121~130
DOI : 10.5139/JKSAS.2009.37.2.121
An unsteady numerical simulation method for an autorotating rotor in forward flight was developed. The flapping and rotational equations of motion of autorotation are continuously integrated for given time steps, meanwhile the induced velocity field at disc plane is obtained by the dynamic inflow theory embodying the unteadiness. The transitions from arbitrary initial states to equilibrium states were simulated. Steady autorotations as numerical solutions of equations were predicted by using two sources of blade airfoil data. The simulations using airfoil data which were obtained by a two dimensional Navier-Stokes solver in terms of angles of attack and Reynolds numbers have shown good agreements with wind tunnel experimental results.
A Study on Updating of Analytic Model of Dynamics for Aircraft Structures Using Optimization Technique
Lee, Ki-Du ; Lee, Young-Shin ; Kim, Dong-Soo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 131~138
DOI : 10.5139/JKSAS.2009.37.2.131
Analytical modal verification is considered as the process to provide an acceptable description of the subject structure`s behaviour. In general, results of original analytical model are different with actual structure results to uncertainty like non-linearity of material, boundary and modified shape, etc. In this paper, the dynamic model of glider`s wing is correlated with static deformation and vibration test results by goal-attainment method, multi-objects optimization technique. The structural responses are predicted by using finite element method and optimization is carried out by using the SQP(sequential quadratic programming) method which is widely used in the constrained nonlinear optimization problem. The MAC(Modal Assurance Criterion) is used to modify the mode shapes and quantify the similarity.
Vibration Reduction of Composite Helicopter Blades using Active Twist Control Concept
Pawar, Prashant M. ; You, Young-Hyun ; Jung, Sung-Nam ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 139~146
DOI : 10.5139/JKSAS.2009.37.2.139
In this study, an assessment is made for the helicopter vibration reduction of composite rotor blades using an active twist control concept. The piezoceramic shear actuation mechanism along with elastic couplings of composite blades is used for vibration reduction. The rotor blades are modeled as composite box-beams with actuator layers bonded on the outer surfaces of the thin-walled section. The governing equations of motion for helicopter blades are obtained using Hamilton`s principle. A time domain unsteady aerodynamic theory with free wake model is used to obtain the airloads. Various rotor configurations with different elastic couplings with appropriate actuator placement are used to investigate the hub vibration characteristics. Numerical results show that a substantial reduction of
/rev hub vibration can be achieved using the optimal control algorithm.
Buckling of Filament Wound Thick Composite Cylinders under External Hydrostatic Pressure
Moon, Chul-Jin ; Hur, Seong-Hwa ; Ahn, Jung-Hee ; Kweon, Jin-Hwe ; Choi, Jin-Ho ; Cho, Jong-Rae ; Cho, Sang-Rae ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 147~155
DOI : 10.5139/JKSAS.2009.37.2.147
The buckling and failure of filament wound thick composite cylinders under external hydrostatic pressure were investigated by the finite element analysis and test. ACOS, MSC.NASTRAN, and MSC.MARC were used for finite element analysis. T700 carbon-epoxy filament wound composite cylinders were fabricated to have winding angles of
, and tested to verify the finite element analysis. Among the softwares, ACOS predicted buckling load the best with about 1.7~14.3% deviation from test. Analysis and test shows cylinders do not recover the initial buckling pressure after buckling and directly lead to final failure.
Multi-sensor Fusion Filter for the Flight Safety System of a Space Launch Vehicle
Ryu, Seong-Sook ; Kim, Jeong-Rae ; Song, Yong-Kyu ; Ko, Jeong-Hwan ; Choi, Kyu-Sung ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 156~165
DOI : 10.5139/JKSAS.2009.37.2.156
Threat due to malfunction of space launch vehicles is significant since it is bigger and flights longer range than military missiles or scientific rockets. It is necessary to implement a flight safety system to minimize the possible hazard. Design objective of the tracking filter for the flight safety system is different from conventional tracking filters since estimation reliability is more emphasized than estimation accuracy. In this paper, a fusion tracking filter was implemented for processing multi-sensor data from a space launch vehicle. The filter performance is evaluated by analyzing the error of the estimated position and instantaneous impact point. Also a fault detection algorithm is implemented to guarantee fusion filter`s reliability under any sensor failure and verified to maintain stability successfully.
Effects of Angled Injection on the Spray Characteristics of Liquid Jets in Subsonic Crossflow
Kim, Min-Ki ; Song, Jin-Kwan ; Lee, Jang-Su ; Yoon, Young-Bin ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 166~174
DOI : 10.5139/JKSAS.2009.37.2.166
The liquid column trajectory and column breakup length characteristics have been experimentally studied in angled jets injected into subsonic crossflow. Pulsed shadowgraph photography and Planar Liquid Laser Induced Fluorescence measurements were used to determine the angled effects. And the main objectives of this research are to get a empirical formula of liquid column trajectory and breakup length with below the
degree injection angle conditions, and were compared with previous results. It was also found that the empirical formula, which reversed injection conditions of air stream. As the result, This has been shown that liquid column trajectories and column breakup length were spatially dependent on various injection angle, normalized injector exit diameter, air-stream and fuel injection velocity. Furthermore, the empirical formula of liquid column trajectories and breakup length has been some different of drag coefficient results between normal angled injection and reversed injection in subsonic crossflow.
Study on super-hydrophobic electro-spray micro thruster and measurement of micro scale thrust
Lee, Young-Jong ; Yoo, Yong-Hoon ; Tran, Si Bui Quang ; Kim, Sang-Hoon ; Park, Bae-Ho ; Buyn, Do-Young ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 175~180
DOI : 10.5139/JKSAS.2009.37.2.175
In this article, we fabricated polytetrafluoroethylene(PTFE) nozzle treated by ion beam, in order to fabricate polymer based electrospray micro thruster with super hydrophobic nozzle. To obtain the super hydrophobic surface, PTFE surface is treated by argon and oxygen plasma treatment process. The optimal condition is investigated argon and oxygen flow rate as well as the paalied energy level for the treatment process. Fabricated nozzle was evaluated by measuring contact angle, and the surface morphology was examined by using scanning electron microscope(SEM) and atomic force microscope(AFM). We observe that jetting becomes more stable and repeatable on the treated nozzle. And to evaluate performance of fabricated nozzle, we measure micro scale thrust using a cantilever and a nozzle treated by ion beam laser displacement sensor.
A Study on the Helicopter Composite Blade Impact Loads
Lee, Hyun-Cheol ; Jeon, Boo-Il ; Moon, Jang-Soo ; Yee, Seok-June ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 181~186
DOI : 10.5139/JKSAS.2009.37.2.181
The objective of this study is ensuring safety of cabin when the blade impacts into a obstacle by verifying safety of the rotor mast and the transmission using impact loads calculated from the simulation. The rotor mast shall not fail and the transmission shall not be displaced into occupiable space when the main rotor composite blade impact into a 8 inch rigid cylinder in diameter on the outer 10% of the blade at operational rotor speed. To calculate the reaction loads at the spherical bearing and lead-lag damper, blade impact analysis was performed with FE model consist of composite blade, tree(or rigid cylinder) using elastic-plastic with damage material and several contact surfaces which were created to describe a progress of actual failure. Also, the reaction loads were investigated in change of blade rotation speed and pitch angle.
Design and fabrication of test equipment of RF Telecommand and Telemetry for satellite control
Chang, Lae-Kyu ; Jo, Seong-Won ; Lee, Hyung-Goo ; Hong, Sung-Yong ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 187~192
DOI : 10.5139/JKSAS.2009.37.2.187
Telecommand & telemetry control equipment is needed for the testing of the transponders during the development of satellite. This equipment must have a loopback function to perform the self testing without satellite. The fabrication of the designed system is easier and cheaper than the conventional testing system using direct modulation method. The measured results of fabricated equipment are satisfied with required specifications. A overall path loss of uplink and downlink is 47.8 dB and 42.6 dB, respectively. Also, IMD3 of uplink has measured 60.68 dBc at an output of -50 dBm.
Effects of Cavitation and Drop Characteristics on Oleo-Pneumatic Type Landing Gear Systems
Han, Jae-Do ; Lee, Young-Sin ; Kang, Yeon-Sik ; Ahn, Oh-Sung ; Kong, Jeong-Pyo ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 193~200
DOI : 10.5139/JKSAS.2009.37.2.193
This paper investigated the drop characteristics of oleo pneumatic type landing gear for small aircraft and the effects of cavitations in modeling the landing gear system. The landing gear system employed a simple oleo pneumatic type damper without a metering pin. In general, oleo-pneumatic type landing gears are light-weighted because of it`s simplicity, yet they offer excellent impact absorption characteristics. In this study, the landing gear system was modeled using MSC ADAMS, which offers a drop simulation module. After modeling the system, a series of testing was conducted, using a prototype landing gear system, to validate the analysis model and simulation results. The effect of cavitation was considered in the simulation model to obtain a better correlation between the test and simulation results. The results show that adding the cavitation effect in the simulation model significantly improved the simulation model and better captured the dynamic behaviors of the landing system. Using the `cavitation` model, dynamics characteristics of the landing gear were further evaluated for other landing conditions, such as landing in various angles of slopes.
Study on a 500W Class Wind Turbine using a High Efficiency Composite Blades
Kong, Chang-Duk ; Choi, Su-Hyun ; Park, Hyun-Bum ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 201~208
DOI : 10.5139/JKSAS.2009.37.2.201
Recently, the wind energy has been widely used as a renewable energy resource due to lack and environmental issues of the mostly used fossil fuel. This work is to develop a 500W class small wind turbine blade which will be applicable to relatively low speed region like Korea and for the domestic use. For this blade a high efficiency wind turbine blade was designed with the proposing aerodynamic design procedure, and a light and low cost composite structure blade was designed considering fatigue life. Structural analyses including load case study, stress, deformation, buckling and vibration analysis were performed using the Finite Element Method. The fatigue life was estimated using the load spectrum analysis and the Miner rule. In order to evaluate the designed blade, the structural and aerodynamic performance tests were carried out, and the test results were compared with the analysis results.
Preliminary Validation of Wind Turbine Generator System Performance Analysis S/W, WINSIM
Mun, Jung-Heu ; No, Tae-Soo ; Park, Jong-Hyuk ; Kim, Sung-Ju ;
Journal of the Korean Society for Aeronautical & Space Sciences, volume 37, issue 2, 2009, Pages 209~214
DOI : 10.5139/JKSAS.2009.37.2.209
The simulation software for predicting the performance of a wind turbine generator system (WTGS) is validated using the field measured data obtained from the idling test run of a dual rotor wind turbine recently developed and installed in Korea. Both steady-state and transient responses at low and high wind conditions are compared with the theoretically predicted ones from the simulation software WINSIM.