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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Aeronautical and Space Sciences
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Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 12, Issue 4 - Dec 2011
Volume 12, Issue 3 - Sep 2011
Volume 12, Issue 2 - Jun 2011
Volume 12, Issue 1 - Mar 2011
Selecting the target year
An Overview of Flutter Prediction in Tests Based on Stability Criteria in Discrete-Time Domain
Matsuzaki, Yuji ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 305~317
DOI : 10.5139/IJASS.2011.12.4.305
This paper presents an overview on flutter boundary prediction in tests which is principally based on a system stability measure, named Jury`s stability criterion, defined in the discrete-time domain, accompanied with the use of autoregressive moving-average (AR-MA) representation of a sampled sequence of wing responses excited by continuous air turbulences. Stability parameters applicable to two-, three- and multi-mode systems, that is, the flutter margin for discrete-time systems derived from Jury`s criterion are also described. Actual applications of these measures to flutter tests performed in subsonic, transonic and supersonic wind tunnels, not only stationary flutter tests but also a nonstationary one in which the dynamic pressure increased in a fixed rate, are presented. An extension of the concept of nonstationary process approach to an analysis of flutter prediction of a morphing wing for which the instability takes place during the process of structural morphing will also be mentioned. Another extension of analytical approach to a multi-mode aeroelastic system is presented, too. Comparisons between the prediction based on the digital techniques mentioned above and the traditional damping method are given. A future possible application of the system stability approach to flight test will be finally discussed.
Convergence Characteristics of Upwind Method for Modified Artificial Compressibility Method
Lee, Hyung-Ro ; Lee, Seung-Soo ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 318~330
DOI : 10.5139/IJASS.2011.12.4.318
This paper investigates the convergence characteristics of the modified artificial compressibility method proposed by Turkel. In particular, a focus is mode on the convergence characteristics due to variation of the preconditioning factor (
) and the artificial compressibility (
) in conjunction with an upwind method. For the investigations, a code using the modified artificial compressibility is developed. The code solves the axisymmetric incompressible Reynolds averaged Navier-Stokes equations. The cell-centered finite volume method is used in conjunction with Roe`s approximate Riemann solver for the inviscid flux, and the central difference discretization is used for the viscous flux. Time marching is accomplished by the approximated factorization-alternate direction implicit method. In addition, Menter`s k-
shear stress transport turbulence model is adopted for analysis of turbulent flows. Inviscid, laminar, and turbulent flows are solved to investigate the accuracy of solutions and convergence behavior in the modified artificial compressibility method. The possible reason for loss of robustness of the modified artificial compressibility method with
>1.0 is given.
Flutter Control of a Lifting Surface via Visco-Hysteretic Vibration Absorbers
Lacarbonara, Walter ; Cetraro, Marek ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 331~345
DOI : 10.5139/IJASS.2011.12.4.331
In this paper, a visco-hysteretic vibration absorber (VA) is proposed to increase the flutter speed of an airfoil and enhance damping in the pre- and post-flutter regimes. The passive system consists of a parallel arrangement of a dashpot and a rateindependent hysteretic element, represented by the Bouc-Wen differential model. The equations of motion are obtained and various tools of linear and nonlinear dynamics are employed to study the effects of the visco-hysteretic VA in the pre- and postflutter ranges.
Structural Performance Tests of Down Scaled Composite Wind Turbine Blade using Embedded Fiber Bragg Grating Sensors
Kim, Sang-Woo ; Kim, Eun-Ho ; Rim, Mi-Sun ; Shrestha, Pratik ; Lee, In ; Kwon, Il-Bum ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 346~353
DOI : 10.5139/IJASS.2011.12.4.346
In this study, the structural performance tests, i.e., static tests and dynamic tests of the composite wind turbine blade, were carried out by using the embedded fiber Bragg grating (FBG) sensors. The composite wind turbine blade used in the test is the 1/23 scale of the 750 kW composite blade. In static tests, the deflections along the blade were evaluated. Evaluations were carried out with simple beam theory and quadratic fitting method by using the embedded FBG sensors to predict the structural behavior with respect to the load. The deflections were compared to those obtained from the laser displacement sensor and electric strain gauges. They showed good agreement. Modal tests were performed to investigate the dynamic characteristics using the embedded FBG sensors. The natural frequencies obtained from the FBG sensors corresponding to the nine mode shapes of the blade were compared to those from the laser Doppler vibrometer. They were found to be consistent with each other. Therefore, it is concluded that the embedded FBG sensors have a great capability for measuring the structural performances of the composite wind turbine blade when structural performance tests are carried out.
An Airborne Cycloidal Wind Turbine Mounted Using a Tethered Balloon
Hwang, In-Seong ; Kang, Wang-Gu ; Kim, Seung-Jo ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 354~359
DOI : 10.5139/IJASS.2011.12.4.354
This study proposes a design for an airborne wind turbine generator. The proposed system comprises a cycloidal wind turbine adopting a cycloidal rotor blade system that is used at a high altitude. The turbine is mounted on a tethered balloon. The proposed system is relatively easier to be realized and stable. Moreover, the rotor efficiency is high, which can be adjusted using the blade pitch angle variation. In addition, the rotor is well adapted to the wind-flow direction change. This article proves the feasibility of the proposed system through a sample design for a wind turbine that produces a power of 30 kW. The generated wind power at 500 m height is nearly 3 times of that on the ground.
An Adaptive Control Approach for Improving Control Systems with Unknown Backlash
Han, Kwang-Ho ; Koh, Gi-Ok ; Sung, Jae-Min ; Kim, Byoung-Soo ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 360~364
DOI : 10.5139/IJASS.2011.12.4.360
Backlash is common in mechanical and hydraulic systems and severely limits overall system performance. In this paper, the development of an adaptive control scheme for systems with unknown backlash is presented. An adaptive backlash inverse based controller is applied to a plant that has an unknown backlash in its input. The harmful effects of backlash are presented. Compensation for backlash by adding a discrete adaptive backlash inverse structure and the gradient-type adaptive algorithm, which provides the estimated backlash parameters, are also presented. The supposed adaptive backlash control algorithms are applied to an aircraft with unknown backlash in the actuator of control surfaces. Simulation results show that the proposed compensation scheme improves the tracking performance of systems with backlash.
Missile Autopilot Design for Agile Turn Control During Boost-Phase
Ryu, Sun-Mee ; Won, Dae-Yeon ; Lee, Chang-Hun ; Tahk, Min-Jea ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 365~370
DOI : 10.5139/IJASS.2011.12.4.365
This paper presents the air-to-air missile autopilot design for a
heading reversal maneuver during boost-phase. The missile`s dynamics are linearized at a set of operating points for which angle of attack controllers are designed to cover an extended flight envelope. Then, angle of attack controllers are designed for this set of points, utilizing a pole-placement approach. The controllers` gains in the proposed configuration are computed from aerodynamic coefficients and design parameters in order to satisfy designer-chosen criteria. These design parameters are the closed-loop frequency, damping ratio, and time constant; these represent the characteristics of the control system. To cope with highly nonlinear and rapidly time varying dynamics during boost-phase, the global gain-scheduled controller is obtained by interpolating the controllers` gains over variations of the angle of attack, Mach number, and center of gravity. Simulation results show that the proposed autopilot design provides satisfactory performance and possesses good [ed: or "sufficient" or "excellent"] capabilities.
Improvement of a Low Cost MEMS Inertial-GPS Integrated System Using Wavelet Denoising Techniques
Kang, Chang-Ho ; Kim, Sun-Young ; Park, Chan-Gook ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 371~378
DOI : 10.5139/IJASS.2011.12.4.371
In this paper, the wavelet denoising techniques using thresholding method are applied to the low cost micro electromechanical system (MEMS)-global positioning system(GPS) integrated system. This was done to improve the navigation performance. The low cost MEMS signals can be distorted with conventional pre-filtering method such as low-pass filtering method. However, wavelet denoising techniques using thresholding method do not distort the rapidly-changing signals. They can reduce the signal noise. This paper verified the improvement of the navigation performance compared to the conventional pre-filtering by simulation and experiment.
Numerical Prediction of Aviation Fuel Temperatures in Unmanned Air Vehicles
Baek, Nak-Gon ; Lim, Jin-Shik ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 379~384
DOI : 10.5139/IJASS.2011.12.4.379
This paper performs numerical prediction of fuel temperature in the fuel tanks of unmanned air vehicles for both ground static non-operating and in flight transient conditions. The calculation is carried out using a modified Dufort-Frankel scheme. For this calculation, it is assumed that a non-operating vehicle on the ground is subjected to repeating daily cycles of ambient temperature with solar radiation and wind under 1%, with a 20% probability of hot day conditions. The energy conservation equation is used as the governing equation to calculate heat transfer between the fuel tank surface and the ambient environment. Results of the present analysis may be used as the estimated initial values of fuel temperatures in a vehicle`s fuel tank for the purpose of analyzing transient fuel temperatures during various flight missions. This research also demonstrates that the fuel temperature of the front tank is higher than that of the rear tank, and that the difference between the two temperatures increases in the later phases of flight due to the consumption of fuel.
Monte Carlo Simulation on Reliability of a Self-Separable Ejector for Man-Portable Missiles
Lee, Hyo-Nam ; Oh, Jong-Yun ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 385~395
DOI : 10.5139/IJASS.2011.12.4.385
An ejector was developed for man-portable missiles. The ejector can be separated from the missile after the completion of the ejection function even without any additional separation devices. This paper introduces the particular separation mechanism of the ejector and presents the methodology, based on a probabilistic design method, to predict the ejection-and-separation reliability. This approach using Monte Carlo simulation can also be applicable to the reliability prediction of one-shot items suffering from difficulties in estimating or in demonstrating their reliability due to the lack of the number of tests available.
Evaluation of the Combat Aircraft Susceptibility Against Surface-Based Threat Using the Weighted Score Algorithm
Kim, Joo-Young ; Kim, Jin-Young ; Lee, Kyung-Tae ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 4, 2011, Pages 396~402
DOI : 10.5139/IJASS.2011.12.4.396
Aircraft combat survivability is an essential factor in the design of combat aircrafts that operate in an enemy air defense area. The combat aircrafts will be confronted with anti-aircraft artillery and/or surface-to-air missiles (SAM) from the ground, and their survivability can be divided into two categories: susceptibility and vulnerability. This article studies the prediction of susceptibility in the case of a one-on-one engagement between the combat aircraft and a surface-based threat. The weighted score method is suggested for the prediction of susceptibility parameters, and Monte Carlo simulations are carried out to draw qualitative interpretation of the susceptibility characteristics of combat aircraft systems, such as the F-16 C/D, and the hypersonic aircraft, which is under development in the United States, versus ground threat from the SAM SA-10.