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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
International Journal of Aeronautical and Space Sciences
Journal Basic Information
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
Review of Active Rotor Control Research in Canada
Feszty, Daniel ; Nitzsche, Fred ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 93~114
DOI : 10.5139/IJASS.2011.12.2.93
The current status of Canadian research on rotor-based actively controlled technologies for helicopters is reviewed in this paper. First, worldwide research in this field is overviewed to put Canadian research into context. Then, the unique hybrid control concept of Carleton University is described, along with its key element, the "stiffness control" concept. Next, the smart hybrid active rotor control system (SHARCS) projected's history and organization is presented, which aims to demonstrate the hybrid control concept in a wind tunnel test campaign. To support the activities of SHARCS, unique computational tools, novel experimental facilities and new know-how had to be developed in Canada, among them the state-of-the-art Carleton Whirl Tower facility or the ability to design and manufacture aeroelastically scaled helicopter rotors for wind tunnel testing. In the second half of the paper, details are provided on the current status of development on the three subsystems of SHARCS, i.e. that of the actively controlled tip, the actively controlled flap and the unique stiffness-control device, the active pitch link.
Impact and Delamination Failure of Multiscale Carbon Nanotube-Fiber Reinforced Polymer Composites: A Review
Khan, Shafi Ullah ; Kim, Jang-Kyo ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 115~133
DOI : 10.5139/IJASS.2011.12.2.115
Fiber reinforced polymer composites (FRPs) are being increasingly used for a wide range of engineering applications owing to their high specific strength and stiffness. However, their through-the-thickness performance lacks some of the most demanding physical and mechanical property requirements for structural applications, such as aerospace vehicles and military components. Carbon nanotubes (CNTs) and carbon nanofibers (CNFs), due to their excellent mechanical, thermal and electrical properties, offer great promise to improve the weak properties in the thickness direction and impart multi-functionality without substantial weight addition to FRPs. This paper reviews the progress made to date on i) the techniques developed for integration of CNTs/ CNFs into FRPs, and ii) the effects of the addition of these nanofillers on the interlaminar properties, such as such interlaminar shear strength, interlaminar fracture toughness and impact damage resistance and tolerance, of FRPs. The key challenges and future prospects in the development of multiscale CNT-FRP composites for advanced applications are also highlighted.
Aeroelastic Behaviour of Aerospace Structural Elements with Follower Force: A Review
Datta, P.K. ; Biswas, S. ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 134~148
DOI : 10.5139/IJASS.2011.12.2.134
In general, forces acting on aerospace structures can be divided into two categories-a) conservative forces and b) nonconservative forces. Aeroelastic effects occur due to highly flexible nature of the structure, coupled with the unsteady aerodynamic forces, causing unbounded static deflection (divergence) and dynamic oscillations (flutter). Flexible wing panels subjected to jet thrust and missile type of structures under end rocket thrust are nonconservative systems. Here the structural elements are subjected to follower kind of forces; as the end thrust follow the deformed shape of the flexible structure. When a structure is under a constant follower force whose direction changes according to the deformation of the structure, it may undergo static instability (divergence) where transverse natural frequencies merge into zero and dynamic instability (flutter), where two natural frequencies coincide with each other resulting in the amplitude of vibration growing without bound. However, when the follower forces are pulsating in nature, another kind of dynamic instability is also seen. If certain conditions are satisfied between the driving frequency and the transverse natural frequency, then dynamic instability called 'parametric resonance' occurs and the amplitude of transverse vibration increases without bound. The present review paper will discuss the aeroelastic behaviour of aerospace structures under nonconservative forces.
Effect of Mesh Size on the Viscous Flow Parameters of an Axisymmetric Nozzle
Haoui, Rabah ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 149~155
DOI : 10.5139/IJASS.2011.12.2.149
The viscous flow in an axisymmetric nozzle was analyzed while accounting for the mesh sizes in both in the free stream and the boundary layer. The Navier-Stokes equations were resolved using the finite volume method in order to determine the supersonic flow parameters at the exit of the converging-diverging nozzle. The numerical technique in the aforementioned method uses the flux vector splitting of Van Leer. An adequate time stepping parameter, along with the Courant, Friedrich, Lewis coefficient and mesh size level, was selected to ensure numerical convergence. The boundary layer thickness significantly affected the viscous flow parameters at the exit of the nozzle. The best solution was obtained using a very fine grid, especially near the wall at which a strong variation of velocity, temperature and shear stress was observed. This study confirmed that the boundary layer thickness can be obtained only if the size of the mesh is lower than a certain value. The nozzles are used at the exit of the shock tube in order to obtain supersonic flows for various tests. They also used in propulsion to obtain the thrust necessary to the displacement of the vehicles.
Power and Trim Estimation for Helicopter Sizing and Performance Analysis
Laxman, Vaitla ; Lim, Jae-Hoon ; Shin, Sang-Joon ; Ko, Kwang-Ho ; Jung, Sung-Nam ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 156~162
DOI : 10.5139/IJASS.2011.12.2.156
The preliminary design stage of helicopters consists of various operations and in each operation design several detailed analysis tasks are needed. The analysis tasks include performance and the required power estimation. In helicopter design, those are usually carried out by adopting the momentum theory. In this paper, an explicit form of computational analysis based on the blade element theory and uniform/non-uniform inflow model is developed. The other motivation of the present development is to obtain trim and required power estimation for various helicopter configurations. Sectional and hub loads, power, trim, and flapping equations are derived by using a symbolic tool. Iterative computations are carried out till convergence is achieved in the blade response, inflow, and trim. The predictions regarding the trim and power estimation turn out to be correlated well with the experimental results. The effect of inflow is further investigated. It is found that the present prediction for the lateral cyclic pitch angle is improved with the non-uniform inflow model as compared to that by the uniform inflow model. The presently improved trim and power estimation will be useful for future helicopter sizing and performance analysis.
Genetic Algorithm Based Decentralized Task Assignment for Multiple Unmanned Aerial Vehicles in Dynamic Environments
Choi, Hyun-Jin ; Kim, You-Dan ; Kim, Hyoun-Jin ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 163~174
DOI : 10.5139/IJASS.2011.12.2.163
Task assignments of multiple unmanned aerial vehicles (UAVs) are examined. The phrase "task assignment" comprises the decision making procedures of a UAV group. In this study, an on-line decentralized task assignment algorithm is proposed for an autonomous UAV group. The proposed method is divided into two stages: an order optimization stage and a communications and negotiation stage. A genetic algorithm and negotiation strategy based on one-to-one communication is adopted for each stage. Through the proposed algorithm, decentralized task assignments can be applied to dynamic environments in which sensing range and communication are limited. The performance of the proposed algorithm is verified by performing numerical simulations.
Measurement Method and System of Optical Fiber-Based Beam Width Using a Reflective Grating Panel
Lee, Yeon-Gwan ; Jang, Byeong-Wook ; Kim, Yoon-Young ; Kim, Jin-Hyuk ; Kim, Chun-Gon ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 175~178
DOI : 10.5139/IJASS.2011.12.2.175
An optical fiber-based beam width measurement technique is presented. The proposed system can be applied to the optical fiber industry in applications such as lensed fiber, optical fiber based laser beam source, and fiber optic sensor. The measurement system is composed of optical fiber, which is used as a transceiver, and a single grating panel which consists of a multi-reflection area with an even non-reflection area. The grating panel is used to vary the reflected light. When the widths of the reflection area and non-reflection area are larger than the optical beam width, the reflected light is varied at the interface between the reflection area and the non-reflection area by the movement of the grating panel. Experiments were conducted in order to verify the feasibility of the proposed technique. Multi-mode fiber combined with a collimator was selected as an emitter and a receiver, and the beam width measurement system was contrived. Subsequently, the proposed method and the system were verified by comparing the experimental results with the results of the conventional charge-coupled device technique.
Robust Adaptive Output Feedback Control Design for a Multi-Input Multi-Output Aeroelastic System
Wang, Z. ; Behal, A. ; Marzocca, P. ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 179~189
DOI : 10.5139/IJASS.2011.12.2.179
In this paper, robust adaptive control design problem is addressed for a class of parametrically uncertain aeroelastic systems. A full-state robust adaptive controller was designed to suppress aeroelastic vibrations of a nonlinear wing section. The design used leading and trailing edge control actuations. The full state feedback (FSFB) control yielded a global uniformly ultimately bounded result for two-axis vibration suppression. The pitching and plunging displacements were measurable; however, the pitching and plunging rates were not measurable. Thus, a high gain observer was used to modify the FSFB control design to become an output feedback (OFB) design while the stability analysis for the OFB control law was presented. Simulation results demonstrate the efficacy of the multi-input multi-output control toward suppressing aeroelastic vibrations and limit cycle oscillations occurring in pre- and post-flutter velocity regimes.
Numerical Investigation of Aerodynamic Interference in Complete Helicopter Configurations
Lee, Hee-Dong ; Yu, Dong-Ok ; Kwon, Oh-Joon ; Kang, Hee-Jung ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 190~199
DOI : 10.5139/IJASS.2011.12.2.190
Unsteady flow simulations of complete helicopter configurations were conducted, and the flow fields and the aerodynamic interferences between the main rotor, fuselage, and tail rotor were investigated. For these simulations, a three-dimensional flow solver based on unstructured meshes was used, coupled with an overset mesh technique to handle relative motion among those components. To validate the flow solver, calculations were made for a UH-60A complete helicopter configuration at high-speed and low-speed forward flight conditions, and the unsteady airloads on the main rotor blade were compared to available flight test data and other calculated results. The results showed that the fuselage changed the rotor inflow distribution in the main rotor blade airloads. Such unsteady vibratory airloads were produced on the fuselage, which were nearly in-phase with the blade passage over the fuselage. The flow solver was then applied to the simulation of a generic complete helicopter configuration at various flight conditions, and the results were compared with those of the CAMRAD-II comprehensive analysis code. It was found that the main rotor blades strongly interact with a pair of disk-vortices at the outer edge of the rotor disk plane, which leads to high pulse airloads on the blade, and these airloads behave differently depending on the specific flight condition.
Analytical Asymptotic Solutions for Rectangular Laminated Composite Plates
Lee, Jae-Hun ; Cho, Maeng-Hyo ; Kim, Jun-Sik ;
International Journal of Aeronautical and Space Sciences, volume 12, issue 2, 2011, Pages 200~209
DOI : 10.5139/IJASS.2011.12.2.200
An analytical solution for rectangular laminated composite plates was obtained via a formal asymptotic method. From threedimensional static equilibrium equations, the microscopic one-dimensional and macroscopic two-dimensional equations were systematically derived by scaling of the thickness coordinate with respect to the characteristic length of the plate. The onedimensional through-the-thickness analysis was performed by applying a standard finite element method. The derived twodimensional plate equations, which take the form of recursive equations, were solved under sinusoidal loading with simplysupported boundary conditions. To demonstrate the validity and accuracy of the present method, various types of composite plates were studied, such as cross-ply, anti-symmetric angle-ply and sandwich plates. The results obtained were compared to those of the classical laminated plate theory, the first-order shear deformation theory and the three-dimensional elasticity. In the present analysis, the characteristic length of each composite was dependent upon the layup configurations, which affected the convergence rate of the method. The results shown herein are promising that it can serve as an efficient tool for the analysis and design of laminated composite plates.