Aeroelastic behaviour of a wing including geometric nonlinearities

2011 ◽  
Vol 115 (1174) ◽  
pp. 767-777 ◽  
Author(s):  
M. Y. Harmin ◽  
J. E. Cooper
Keyword(s):  
Aspect Ratio ◽  
Rational Fraction ◽  
Reduced Order Models ◽  
Structural Modelling ◽  
Geometric Nonlinearities ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Aeroelastic Model ◽  
Non Linear ◽  
Gust Response

Abstract A procedure for developing efficient aeroelastic reduced order models (ROMs) for aerospace structures containing geometric nonlinearities is described. The structural modelling is based upon a combined modal/FE approach that describes the non-linear stiffening effects from results of non-linear static analyses for a range of prescribed inputs. Once the structural ROM has been defined, it is coupled to the rational fraction approximation of the doublet lattice aerodynamic model corresponding to the wing planform. The aeroelastic model can then be used to predict the dynamic aeroelastic behaviour of the defined structure. The methodology is demonstrated on the aeroelastic model of a flexible high aspect ratio wing with the static deflections, LCO behaviour and gust response being predicted.

scholarly journals On the Potential of Reduced Order Models for Wind Farm Control: A Koopman Dynamic Mode Decomposition Approach

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6513
Author(s):  
Nassir Cassamo ◽  
Jan-Willem van Wingerden
Keyword(s):  
Wind Farm ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Reduced Order Models ◽  
Decomposition Approach ◽  
Reduced Order ◽  
Mode Decomposition ◽  
Non Linear ◽  
Farm Systems ◽  
Turbine Wake

The high dimensions and governing non-linear dynamics in wind farm systems make the design of numerical optimal controllers computationally expensive. A possible pathway to circumvent this challenge lies in finding reduced order models which can accurately embed the existing non-linearities. The work presented here applies the ideas motivated by non-linear dynamical systems theory—the Koopman Operator—to an innovative algorithm in the context of wind farm systems—Input Output Dynamic Mode Decomposition (IODMD)—to improve on the ability to model the aerodynamic interaction between wind turbines in a wind farm and uncover insights into the existing dynamics. It is shown that a reduced order linear state space model can reproduce the downstream turbine generator power dynamics and reconstruct the upstream turbine wake. It is further shown that the fit can be improved by judiciously choosing the Koopman observables used in the IODMD algorithm without jeopardizing the models ability to rebuild the turbine wake. The extensions to the IODMD algorithm provide an important step towards the design of linear reduced order models which can accurately reproduce the dynamics in a wind farm.

scholarly journals Numerical comparison of reduced order models for non-linear vibrations of damped plates

2012 ◽  
Author(s):  
F. Boumediene ◽  
L. Duigou ◽  
A. Miloudi ◽  
J.M. Cadou
Keyword(s):  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Computational Time ◽  
Numerical Comparison ◽  
Processing Unit ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Central Processing ◽  
Non Linear ◽  
Linear Vibrations

This work deals with the computation of the non-linear solutions of the vibration of damped plates by coupling a harmonic balance method and the asymptotic numerical method. These computations can lead to lengthy central processing unit (CPU) times if the solution sought contains an important number of harmonics. In this study, we propose two reduced order models which can be applied to solve this type of problem. Both reduced methods are based on a first computation carried out with a small number of harmonics (here two). Numerical examples of plate vibration show that these algorithms help save a great deal of computational time and can be applied to problems involving numerous harmonics.

Development of an aeroelastic model based on system identification using boundary elements method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rohollah Dehghani Firouz-Abadi ◽  
Mohammad Reza Borhan Panah
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Structural Models ◽  
Elastic Mode ◽  
Content Type ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Aeroelastic Model ◽  
Proposed Model ◽  
Element Method

Purpose The purpose of this paper is to analyze the stability of aeroelastic systems using a novel reduced order aeroelastic model. Design/methodology/approach The proposed aeroelastic model is a reduced-order model constructed based on the aerodynamic model identification using the generalized aerodynamic force response and the unsteady boundary element method in various excitation frequency values. Due to the low computational cost and acceptable accuracy of the boundary element method, this method is selected to determine the unsteady time response of the aerodynamic model. Regarding the structural model, the elastic mode shapes of the shell are used. Findings Three case studies are investigated by the proposed model. In the first place, a typical two-dimensional section is introduced as a means of verification by approximating the Theodorsen function. As the second test case, the flutter speed of Advisory Group for Aerospace Research and Development 445.6 wing with 45° sweep angle is determined and compared with the experimental test results in the literature. Finally, a complete aircraft is considered to demonstrate the capability of the proposed model in handling complex configurations. Originality/value The paper introduces an algorithm to construct an aeroelastic model applicable to any unsteady aerodynamic model including experimental models and modal structural models in the implicit and reduced order form. In other words, the main advantage of the proposed method, further to its simplicity and low computational effort, which can be used as a means of real-time aeroelastic simulation, is its ability to provide aerodynamic and structural models in implicit and reduced order forms.

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