A new nonlinear aeroelastic solver has been described. This aeroelastic solver couples a well-validated finite difference Euler fluid solver to a high-fidelity, finite element structural solver. The structural solver uses a co-rotational formulation to accurately predict large deflection and rotations. The two solvers are implicitly coupled via global subiterations which results in a second-order accurate (in time) aeroelastic solver. The new aeroelastic solver is used to compute the LCO of a cropped delta wing in transonic flow. Previously, the LCOs of this configuration were computed using either a linear structural model or a lower fidelity nonlinear structural model. The results computed using the aeroelastic model which used a linear structural solver compared poorly, both qualitatively and quantitatively, with experiment. When a nonlinear von Karman structural model was used to predict the LCOs of this configuration, the correlation between theory and experiment improved. Using the current aeroelastic solver the quantitative agreement between theory and experiment is not significantly improved over the range of dynamic pressures for which experimental results are reported. However at higher dynamic pressures the LCO amplitudes computed using the current model and the model which uses von Karman theory start to deviate from each other. The higher-order treatment of large rotation in the current structural model allows for a more accurate prediction of the large amplitude LCOs at these higher dynamic pressures. As a result of these differences in LCO magnitudes at the higher dynamic pressures, flow features which are dependent on the structural deflection and rotation of the wing are strengthened using the current model. LCO results were also computed using the nonlinear co-rotational finite element model for two different structural meshes which contained less (and better shaped) structural elements. A thin-plate spline routine was used to interpolate displacements and pressures between the dissimilar structural and fluid meshes. The LCO magnitudes computed using these two meshes compared well with the baseline case. In addition, better convergence of the nonlinear structural solver was noted for these two meshes due to the improved structural mesh quality. An additional LCO computation was performed at a dynamic pressure of 5.46 psi using the baseline mesh and a finite strain element which employed an updated Lagragian methodology for computation of the nonlinear structural stiffness. The finite strain element also takes into account corrections in the stiffness matrix due to the follower nature of the pressure loading. The LCO magnitude computed with this model was approximately 10 % less than the baseline case. Use of this element also resulted in improved convergence characteristics of the nonlinear structural solver, with only 1-2 Newton-Raphson iterations needed per fluid-structural subiteration.


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    Titel :

    Aeroelastic prediction of the limit cycle oscillations of a cropped delta wing


    Weitere Titelangaben:

    Aeroelastische Vorhersage begrenzter zyklischer Schwingungen bei einem gekröpften Deltaflügel


    Beteiligte:
    Attar, P.J. (Autor:in) / Gordnier, R.E. (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2006


    Format / Umfang :

    14 Seiten, 10 Bilder, 23 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch






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