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International Review of Aerospace Engineering - October 2012 (Vol. 5 N. 5) - Papers






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International Review of Aerospace Engineering - Papers



go to top   Robust Control of an Unmanned Aerial Blimp
        by H. Miber, L. Beji


Abstract - In this paper, we address the problem of trajectory tracking in various navigation planes of unmanned aerial vehicle of blimp type with robust controller. The coupled dynamic equations of the blimp including the kinematics are distributed into the blimp's three geometric planes. In lateral plan P(YGZ) we show that the dynamics of the airship is controlled by flatness and the stability tracking is conducted by a robust controller. This problem of tracking is described by a Linear Invariant Time system (LTI). The approach used in this case is based on the notion of quadratic stabilization where a single Lyapunov function is used to ensure the stability of the LTI system. In the horizontal plane P(XGY) and longitudinal plan P(XGZ), the dynamic behavior of the airship is quite complex. The problem of the tracking of the blimp's trimmed flight is described by a Linear Parameter Varying system (LPV). In theses sections , we use a LPV control by state output feedback to solve this problem. The technique of control used in the two sections is based on finding a parameter dependent Lyapunov functions ensures the robust stability of the LPV system. This leads to a convex optimization problem which can be solved using Linear Matrix Inequalities (LMIs). The theoretical results are tested by simulation in MATLAB while using the LMI toolbox.

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Keywords: Aerial Blimp, LPV System, Lyapunov, Flatness, LPV Control, LMIs.



go to top   Wind Tunnel Experiments with Simulated Ice Fragments
        by Michael Papadakis, Hsiung-Wei Yeong, Koji Shimoi, See-Ho Wong


Abstract - Aircraft icing certification requires an assessment of the aircraft safety risks posed by ice shedding events. The research described in this paper was part of an effort at Wichita State University to develop and validate tools for ice shedding analyses. An experimental methodology was developed to document the trajectories of simulated ice shapes released in a wind tunnel facility. This methodology was employed to obtain experimental trajectory data for three ice fragments. The experiments were conducted in the Wichita State University 2.1 m x 3.0 m wind tunnel facility at an airspeed of 71.5 m/s. The simulated ice shapes tested included a 15.2 cm square flat plate simulating runback ice, a 22.5-min LEWICE ice shape representing the upper horn of a wing leading edge ice shape, and a 45-min LEWICE ice shape simulating aircraft antenna ice formation. The experimental data revealed that the flat plate rotated about its pitch axis as it traversed the length of the tunnel test section. The 22.5-min LEWICE fragment exhibited oscillatory behavior and was observed to ascend after release into the tunnel airstream due to the lift generated by the horn orientation. The 45-min fragment travelled along a straight path with negligible oscillation or rotation. A computer code developed at Wichita State University was used to compute the trajectories of the flat plate and LEWICE fragments. In general, the computed trajectories were found to be in good agreement with the experimental data.

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Keywords: Aircraft Icing, Ice Shedding, Ice Particle Trajectory, Ice Fragment.



go to top   Analysis of Anisotropy and Viscoelastic Properties of Composite Solid Propellant and Its Suitability for Use in Solid Rocket Under Field Deployment
        by P. Bose, K. M. Pandey


Abstract - Solid propellant provides excellent transportability, long storage life, ease of design, manufacturing and packaging. It is safe to handle and simple to operate and suits field deployment. Hence it is best suited when used in shouldered fired rocket launcher and multi barrel rocket launcher application. The stress remains close to linear till one third part of strain/deflection is reached. As the strain rate increases both elastic modulus and tensile strength also increases. It is also observed that the composition shows anisotropy under load. Variation of ultimate tensile strength (UTS) and ultimate compressive strength (UCS) of the same composition is due to macroscopically, the fuel and the oxidiser of composite propellant form a heterogeneous mixture. When put under gradually increasing strain, here as the strain rate increases both elastic modulus and tensile strength also increase. This is because the propellant requires adequate reaction time to respond to higher strain rate. This is the property of the material of viscoelastic nature. Design of a solid propellant grain is governed by ballistic, processing and structural integrity requirements. The composite solid propellant displays a viscoelastic property which favours storage, handling and its transportability. The propellant also displays anisotropy due to its macroscopic nonhomogeneity. But the propellant is considered as it meets the ballistic properties. Moreover, the propellant burns for very small duration in rocket launcher application. The burning time of composite solid propellant in launchers of shoulder fired role as well as multi barrel rocket launcher (MBRL) role is less than 10 s. Here the ballistic properties outweigh the anisotropy. In this paper detailed analysis has been carried out to investigate the anisotropy and viscoelastic property of solid composite propellant and implication of these properties for its use in rocket launcher applications.
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Keywords: Anisotropy, Ballistic Properties, Composite Propellant, Heterogeneous Mixture, MBRL, UTS, UCS, Viscoelastic Properties.



go to top   Spectral Analysis and Independent Component Separation for Aero-Engine Rotor Vibration Signals
        by Xiangyang Jin, Xiangyi Guan, Lili Zhao, Hanlin Yang, Ming Pang, Tiefeng Zhang


Abstract - Based on the traditional spectral analysis method, the blind source separation technology has been employed to conduct the vibration source separation for the aircraft engine vibration signals. At the same time, the blind source separation theory has been also introduced and the feasibility of its application in the processing of aero-engine vibration signals has been also discussed. Afterwards, the excessive vibration problem of some turbofan engine has been conducted the fault diagnosis analysis. Finally, the Independent Component Analysis algorithm has been adopted to analyze the vibration signals and the vibration source signals of engine have been also separated. It is indicated that the technology which combines the independent component analysis and the spectral analysis in the process of discussing the vibration signals of engine can effectively separate the vibration source signals and improve the accuracy of fault diagnosis.

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Keywords: Aero-Engine, Signal Separation, Spectral Analysis, Fault Diagnosis.



go to top   Computer-Aided Modelling and Simulation of Aircraft Generator Failure
        by Xudong Shi, Yaowen Yang, Tao Jing


Abstract - The corresponding fault signature waveform of the main generator terminal output changes before many aircraft generator failures occur. Therefore, detection and analysis of the output waveform change is an effective measure for diagnosing the interior fault of the aircraft generator. In this work, aiming at the basic fault characteristics, the simulation of generator fault characteristics at the three-phase unbalanced situation, through switching the general model to the phase-domain model of the generator, is put forward. The simulation results show that the model more accurately reflects the normal and fault operation of the aircraft generator.

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Keywords: Aircraft Generator, Output Waveform Change, Fault Characteristics.



go to top   Aeroengine Data Correlation by Means of Detrended Fluctuation Analysis
        by Keqiang Dong, You Gao, Changjun Zhu


Abstract - This paper gives a detailed analysis to the correlation and cross-correlation characteristics for aeroengine dynamics. By applying the detrended fluctuation analysis, we find that the detrended fluctuation function of the aeroengine series follows a power-law, F(s)~sα , where the parameter α, called correlation exponent, represents the correlation properties in signals. Specially, the correlation property of the exhaust gas temperature (EGT) and engine fan speeds (N1 and N2) are similar.
Further, we consider the cross-correlation of the aeroengine time series. Interestingly, the properties of detrended cross-correlation analysis function between exhaust gas temperature (EGT) and engine fan speeds (N1) is analogous to the functional properties obtained by exhaust gas temperature (EGT) and engine fan speeds (N2). These results indicate that the correlation and cross-correlation features exist in the aeroengine system.
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Keywords: Detrended Fluctuation Analysis, Detrended Cross-Correlation Analysis, Exhaust Gas Temperature, Engine Fan Speeds.



go to topLagrange’s Equations for Rocket-Type Variable Mass Systems
        by A. Nanjangud, F. O. Eke


Abstract - This paper presents a derivation of the equations of motion of variable mass systems based on Lagrange’s equations. The derivation makes use of the control volume concept and exploits Reynolds Transport Theorem to generate equations that are reasonably compact, yet general enough to capture the dynamical behavior of variable mass systems of any shape and configuration. The only restriction is that the system should include a solid base. The equations are thus very well suited for the study of the translational as well as rotational motions of rockets and similar systems.
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Keywords: Dynamics, Rockets, Variable Mass Systems.



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