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aeroservoelasticity analysis method based on an error analytical form applied on a business aircraft

JOURNAL OF VIBRATION AND CONTROL 2008年第8期14卷 1217-1230页

作者： Biskri, D. E. Botez, R. M. Stathopoulos, N. Therien, S. Dickinson, M. Rathe, A. Ecole Technol Super Dept Automated Prod Engn Montreal PQ H3C 1K3 Canada Bombardier Aeronaut Dorval PQ Canada

aeroservoelasticity is a multidisciplinary study that combines the following disciplines: aerodynarnics, aeroelasticity and servo-controls. For aeroelasticity studies, the Doublet Lattice Method (DLM) is used to calculate the aerodynamic unsteady forces for a set of reduced frequencies k and Mach numbers M on a business aircraft in the Subsonic flight regime. There are three classical methods in the aeroservoelasticity used to approximate these forces Q(k, M) by rational functions in the Laplace domain Q((s) over bar): Least Square (LS), Matrix Pade (MP) and Minimum State (MS). A new method called Corrected Least Square (CLS) is presented. This new method uses an analytical form of the error as a function of Laplace variable similar to the analytical form of the aerodynamic forces calculated by use of the LS method. The new CLS method does not take additional time to the computation of the unsteady aerodynamic forces when compared to the LS method, and the aerodynamic forces calculated with the CLS method are closer to the aerodynamic forces data in the frequency domain than the aerodynamic forces calculated by the standard LS method. The new CLS method applied on a business aircraft gives better results (flutter speeds and frequencies) and faster (as it uses smaller number of lag terms) than the LS method.

关键词： aeroelasticity aerodynamics aeroservoelasticity least squares

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Nonlinear Helicopter Rigid-Elastic Coupled Modeling with Its Applications on aeroservoelasticity Analysis

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AIAA JOURNAL 2022年第1期60卷 102-112页

作者： Wang, Luofeng Chen, Renliang Nanjing Univ Aeronaut & Astronaut Coll Aerospace Engn Natl Key Lab Sci & Technol Rotorcraft Aeromech Nanjing 210016 Peoples R China

This paper represents a new mathematical model for helicopters with flexible fuselages. The theory connects the two commonly separated research areas of flight, dynamics and structural dynamics, by considering all necessary effects of a flexible fuselage on helicopter flight dynamic characteristics. They are rigid-elastic couplings of the flexible fuselage between six rigid-body degrees of freedom and elastic deformations, along with inertial and kinematic couplings between subcomponents and the fuselage. This is achieved by using the floating frame theory and deriving the acceleration coupling matrices of subcomponents analytically. In addition, the obtained formulation is explicitly decoupled such that all unknown absolute accelerations could be obtained in a single step without iterations, which could improve computational efficiency greatly. This model is suited for aeroservoelastic analysis, and is particularly suited for heavy lift helicopters (HLH) because they usually have slower turning rotors and more flexible fuselages due to their larger scale, leading to closer frequency ranges between rigid body motions and high-frequency rotor and structural modes. The model is validated before being applied to a numerical example of a sample HLH with a feedback loop for stability augmentation. The results show that the feedback loop connects actuators, fuselage deformation, and rigid body motion and induces divergent oscillation, which is the aeroservoelastic instability that cannot be predicted without the additional sensor measurements feedback caused by dynamic deformation. Since the 10-second step response could be calculated in three seconds, the presented helicopter mathematical model is expected to be used in real-time simulations or even further in pilot-in-the-loop simulations, ultimately helping with the design of modern helicopters with nonnegligible fuselage flexibility.

关键词： Heavy Lift Helicopters aeroservoelasticity Empennage Feedback Loop Elastic Deformation Sensors Pilot Mathematical Models Actuators Structural Dynamics

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New mixed method for unsteady aerodynamic force approximations for aeroservoelasticity studies

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JOURNAL OF AIRCRAFT 2006年第5期43卷 1538-1542页

作者： Biskri, Djallel Botez, Ruxandra. M. Stathopoulos, N. Therien, S. Rathe, A. Dickinson, M. Ecole Technol Super Dept Automated Prod Engn Montreal PQ H3C 1K3 Canada Bombardier Aerosp Montreal PQ Canada

This new MxState method will allow us to obtain the MS approximation withoutpassing through along iterative algorithm. In this manner, we minimize the number of lag terms inthe MS approximation term, which means that the lags applied to the two terms: Σ from i=1 ton_(Lag) (A_(i+2))/(s+b_i)s and D[sI — R]~(-1)Es will be the same. We compared the flutter speedsand frequencies found by the flutter standard nonlinear method with the flutter speeds andfrequencies found by the LS approximation method with 8 lag terms, and with the flutter speeds andfrequencies found by the new MxState with 1 to 4 lag terms for the CL-604 aircraft. We found thatthe MxState method with 4 lags gives results that are very close to the results of the standard pkflutter and the LS approximation method with 8 lags. We noticed that the best error values error forboth cases (symmetric and antisymmetric modes) are those of the MxState with 4 lags. These resultswere obtained on a business aircraft with 44 symmetric modes and 50 antisymmetric modes.

关键词： UNSTEADY flow (Aerodynamics) aeroservoelasticity AERODYNAMICS ERROR analysis (Mathematics) FLUTTER (Aerodynamics)

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Control law design for transonic aeroservoelasticity

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AEROSPACE SCIENCE AND TECHNOLOGY 2007年第2-3期11卷 136-145页

作者： Zhang, Weiwei Ye, Zhengyin Northwestern Polytech Univ Natl Key Lab Aerodynam Design & Res Xian 710072 Peoples R China

Existing computational transonic aeroservoelastic researches focus on directly coupling the structural dynamic equations, CFD solver and servo system in time domain, study the effect of the given feedback control laws on the responses of the aeroelastic system. These works have not involved the design of the flutter active control law. The non-linearity of transonic flow brings great difficulties to aeroservoelastic analysis and design. Recent research of the unsteady aerodynamic reduced order models (ROM) based on CFD provides a challenging approach for transonic aeroservoelastic analysis and design. Coupling the structural state equations with the aerodynamic state equations of the wing and the control surface based on the ROM, we construct a transonic acroservoelastic model in state-space. Then the sub-optimal control method based on output feedback is used to design the flutter suppressing law. The study first demonstrates the open loop of the Benchmark Active Controls Technology (BACT) wing. The computational results of the CFD direct simulation method and the ROM analysis method are both agree well with the experimental data. Then both the closed loop time responses and the flutter results by ROM technique are compared with those of numerical aeroservoelastic simulation based on Euler codes to validate the correctness of the design method of the control law and aeroservoelastic analysis method. An increase of up to 20% of the speed index can be achieved by the control law designed by sub-optimal control method for this model. (c) 2007 Elsevier Masson SAS. All rights reserved.

关键词： transonic flow aeroservoelasticity flutter ROM sub-optimal control

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Chebyshev polynomials for unsteady aerodynamic calculations in aeroservoelasticity

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JOURNAL OF AIRCRAFT 2006年第1期43卷 165-171页

作者： Dinu, AD Botez, RM Cotoi, I Univ Quebec Dept Automated Prod Engn Ecole Technol Super Montreal PQ H3C 1K3 Canada

The aerodynamic forces in the reduced frequency domain have to be approximated in the Laplace domain, in order to study the effects of the control laws on the flexible aircraft structure. This type of approximation of unsteady generalized aerodynamic forces from the frequency domain into the Laplace domain, acting on a Fly-By-Wire aircraft, presents an important challenge in the aeroservoelasticity area. In this paper we present a new method for approximation of the generalized aerodynamic forces, using Chebyshev polynomials and their orthogonality properties. A comparison of results e.:pressed in terms of flutter speeds and frequencies obtained by this new method and by the Pade method is presented here. This new approximation method gives excellent results with respect to Pade method and is validated on the aircraft test model from NASA Dryden Flight Research Center.

关键词： aeroservoelasticity CHEBYSHEV POLYNOMIALS approximation experimental model flexible air vehicles Polynomial Approximation method unsteady aerodynamics Laplace control law

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Studies on aeroservoelasticity semi-physical simulation test for missiles

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Science China(Technological Sciences) 2012年第9期55卷 2482-2488页

作者： WU ZhiGang CHU LongFei YUAN RuiZhi YANG Chao TANG ChangHong School of Aeronautic Science and Engineering Beijing University of Aeronautics and AstronauticsBeijing 100191China The First Aircraft Institute Aviation Industry Corporation of ChinaXi'an 710089China

Missiles may be damaged when aeroservoelastic problem occurs,which is caused by the interaction of structure flexibility and flight control *** of the limit of wind tunnel test condition,numerical methods are mostly used in previous aeroservoelastic ***,series of assumptions and simplification on structures,aerodynamics and flight control systems are unavoidably introduced,and various nonlinear factors are also ignored,therefore,they result in considerable errors.A novel method called aeroservoelasticity semi-physical simulation test is proposed in this paper,which takes the flexible missile with control system as the test *** signals at several locations of the missile are measured by accelerometers,then corresponding unsteady aerodynamics is computed based on the fact that airflow at high Mach is nearly quasi-steady,and finally unsteady aerodynamics is exerted simultaneously by shakers at certain locations of the *** aeroservoelasticity semi-physical simulation test system can be constructed after the control system is *** loop transfer function test and closed loop stability test are carried out in *** test principle and method proposed in this paper are verified by the concordance between the results of numerical simulation and experiment.

关键词： aeroservoelasticity semi-physical simulation unsteady aerodynamic aerodynamic derivative method shaker missile

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Method based on the LS approach used for flutter aeroservoelasticity analysis studies

Method based on the LS approach used for flutter aeroservoel...

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5th IASTED International Conference on Modelling, Simulation and Optimization

作者： Botez, RM Biskri, DE Terrien, S Rathe, A Stathopoulos, N Dickinson, M Ecole Technol Super Dept Automated Prod Engn Montreal PQ H3C 1K3 Canada Bombardier Aeronaut Dorval PQ Canada

ISBN: (纸本)0889865248

aeroservoelasticity study is a multidisciplinary study of three main disciplines: unsteady aerodynamics, aeroelasticity and servo-controls. For aeroelasticity studies, the Doublet Lattice Method DLM is used to calculate the aerodynamic unsteady forces Q(k, M) for a set of reduced frequencies k and Mach numbers on a business aircraft in the subsonic flight regime. In these studies, three classical methods are used to approximate these unsteady generalized forces Q(k, M) by rational functions in the Laplace domain Q((s) over bar): Least Square LS, Matrix Pade MP and Minimum State MS. In this paper, we present a new method, which uses an analytical form of the error as function of Laplace variable s similar to the analytical form of the aerodynamic forces calculated by use of the Least Square LS method. The results obtained by this method are compared to the results obtained by the LS method as this new method CLS is based on the LS approach. We found that the use of the new method does not include an additional time for the computation of unsteady aerodynamic forces with respect to the LS method. We found that new method aerodynamic forces are closer to the aerodynamic forces data in the frequency domain Q(k) than the aerodynamic forces calculated by the standard LS method. We applied this new method to an existing business aircraft and we found that our method here presented gives between 33% and 99% reduction rate in comparison with the LS method.

关键词： aeroelasticity aeroservoelasticity control laws aerodynamics flexible aircraft

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Fly-by-feel aeroservoelasticity

Fly-by-feel aeroservoelasticity

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作者： Suryakumar, Vishvas Samuel Texas A&M University

学位级别：Ph.D.

Recent experiments have suggested a strong correlation between local flow features on the airfoil surface such as the leading edge stagnation point (LESP), transition or the flow separation point with global integrated quantities such as aerodynamic lift. “Fly-By-Feel” refers to a physics-based sensing and control framework where local flow features are tracked in real-time to determine aerodynamic loads. This formulation offers possibilities for the development of robust, low-order flight control architectures. An essential contribution towards this objective is the theoretical development showing the direct relationship of the LESP with circulation for small-amplitude, unsteady, airfoil maneuvers. The theory is validated through numerical simulations and wind tunnel tests. With the availability of an aerodynamic observable, a low-order, energy-based control formulation is derived for aeroelastic stabilization and gust load alleviation. The sensing and control framework is implemented on the Nonlinear Aeroelastic Test Apparatus at Texas A&M University. The LESP is located using hot-film sensors distributed around the wing leading edge. Stabilization of limit cycle oscillations exhibited by a nonlinear wing section is demonstrated in the presence of gusts. Aeroelastic stabilization is also demonstrated on a flying wing configuration exhibiting body freedom flutter through numerical simulations.

关键词： aeroservoelasticity Unsteady Aerodynamics Flutter Suppression Thesis

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NASA Technical Reports Server (Ntrs) 20000080368: Pilot Comments from the Boeing High Speed Research Aircraft, Cycle 3, Simulation Study of the Effects of aeroservoelasticity (Larc.3)

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2017年

NASA Technical Reports Server (Ntrs) 20000080368: Pilot Comments from the Boeing High Speed Research Aircraft, Cycle 3, Simulation Study of the Effects of aeroservoelasticity (Larc.3) by NASA Technical Reports Server ... 详细信息

关键词： (larc.3) (ntrs) 20000080368: aeroservoelasticity aircraft, bailey, melvin l. [editor] boeing boeing aircraft cards data recording motion simulators nasa technical reports server (ntrs) pilots simulation

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NASA Technical Reports Server (Ntrs) 19890014943: Recent Activities Within the aeroservoelasticity Branch at the NASA Langley Research Center

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2016年

NASA Technical Reports Server (Ntrs) 19890014943: Recent Activities Within the aeroservoelasticity Branch at the NASA Langley Research Center by NASA Technical Reports Server (Ntrs); NASA Technical Reports Server (Ntr... 详细信息

关键词： (ntrs) 19890014943: activities aeroelasticity aeroservoelasticity branch control systems design digital command systems flexible wings flutter analysis gilbert, michael g. gust loads gusts hierarchies least squares method matched filters mathematical models nasa technical reports server (ntrs) noll, thomas e. perry, boyd, iii random processes servomechanisms structural design unsteady aerodynamics

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