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Entomopter maneuverability exchanged by deformations control of flexible flapping wings

Kowalczyk G., Lewitowicz J., Sibilski K.

Journal of KONBiN

2008

No. 5 (8)

93-102

In the background of preparing this paper lies our believe that transferring ideas from the more matured disciple like aircraft technology to emerging animal technology should be beneficial for the later one and vice-versa. One integrated idea, of special interest to both disciplines, is the active flexible wing concept. In this paper we developed aeroelastic analysis for a flexible wing for an imposed harmonic flapping motion about the root chord of the wing. A Matlab code was written based on the analysis. This code was used to find the average lift and thrust of a wing of known aerodynamic and structural properties.

Podstawą podjęcia tej pracy było nasze przekonanie o celowości przeniesienia idei bionicznych do zasad budowy miniaturowych statków powietrznych. Jedną z takich idei jest koncepcja aktywnie odkształcalnych skrzydeł. Na wstępie przedstawiliśmy aeroelastyczne analizy odkształcalnych skrzydeł wykonujących wymuszone ruchy harmoniczne względem cięciwy znajdującej się u ich nasady. Na podstawie tych analiz opracowaliśmy pakiet programów w środowisku Matlab. Następnie pakiet ten zastosowaliśmy do obliczeń średniej wartości siły nośnej i siły ciągu odkształcalnego skrzydła.

The general parallel algorithm for a time-domain aeroelastic analysis

Dul F.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

1998

nr 8

145-152

The time-domain aeroelastic analysis (TDA) consists in direct integration the coupled structural and aerodynamic equations and analyzing the evolution of the solutions to obtain either the critical values of parameters (e.g., the flutter speed) or domains of different types of motion. This approach is quite different comparing with the frequency domain analysis (FDA), in which an assumed harmonic motion of a construction is investigated by inspecting eigenvalues of a matrix problem. The main disadvantage of TDA lies in its high computational costs, which comes from a necessity of repeating of integration of fluid dynamics (CFD) and structure dynamics (CSD) equations of motion. Since each of those repeated steps is independent of another, there is a natural possibility of parallelization of computations which should lead to an essential reduction of computational cost. It is shown in this paper that the above idea may be applied directly to the TDA resulting in a very efficient and sufficiently accurate parallel algorithm. The searching for the critical flutter velocity is accomplished by finding the root of a polynomial being an approximation of the coefficients of energy growth of a relative elastic motion of construction. This polynomial approximation is on a set of coefficients computed for the set of an undisturbed velocities of flow by the identification procedure based on the assumed exponential form of the energy. The energy for a given flow velocity is computed by a direct integration of the CFD and CSD equations. The parallelization of the above idea in carrying on the computation of the coefficients independently for each assumed of velocity, without transfer of data processors. It has been verified in tests performed on the CRAY Superserver 6400 machine, that the proposed parallel TDA algorithm enables one to compute the critical speed with accuracy than 1%, which is sufficient for the purposes. This accuracy depends on the assumption of exponential of the energy of the system. The proposed algorithm is suited well to the machines having moderate number of processors (about ten).