Modeling delta wing limit-cycle oscillations using a high-fidelity structural model

Flutter and limit-cycle oscillations(LCO) of a delta-wing model are studied theoretically and correlated with results from an earlier experiment and an earlier simpler theoretical model. The present theoretical model uses a high-fidelity nonlinear structural model and a linear vortex lattice aerodynamic model. The commercial finite element package ANSYS is selected to model the structure and is coupled to the vortex lattice aerodynamic model using a subiteration procedure to carry out time simulations. The delta-wing model is studied for five angles of attack (0, 1, 2, 3, and 4 deg) and for various flow speeds. Theoretical results are calculated for two different root-chord boundary conditions, that is, fully fixed and also another that allows some in-plane movement at the root chord by attaching stiff in-plane springs that connect the structure to the root boundary. The results obtained using the high-fidelity structural model are compared to earlier results computed using a lower-fidelity von Karman plate theory. For all angles of attack studied here, the correlation between theory and experiment is better for the aeroelastic model, which uses the high-fidelity (ANSYS) structural model. Both flutter velocity and frequency as well as the LCO amplitudes and frequencies that are predicted using the higher-fidelity stuctural model correlate well with experiment. In particular the flutter and LCO results predicted using the high-fidelity structural model are similar, both qualitatively and quantitatively, for the two different in-plane boundary conditions. However the results obtained from the von Karman model differ substantially for the two different in-plane boundary conditions.

[1]  H. Ashley,et al.  Aerodynamics of Wings and Bodies , 1965 .

[2]  B. J. Hsieh,et al.  Non-Linear Transient Finite Element Analysis with Convected Co--ordinates , 1973 .

[3]  R. Cook,et al.  Concepts and Applications of Finite Element Analysis , 1974 .

[4]  E. Dowell,et al.  Aeroelasticity of Plates and Shells , 1974 .

[5]  C. Rankin,et al.  An element independent corotational procedure for the treatment of large rotations , 1986 .

[6]  C. Rankin,et al.  Finite rotation analysis and consistent linearization using projectors , 1991 .

[7]  M. D. Olson,et al.  Large elastic-plastic deformations of slender beams: Co-rotational theory vs. von Karman theory , 1994, Computational Mechanics.

[8]  Earl H. Dowell,et al.  Limit Cycle Oscillations of a Cantilevered Wing in Low Subsonic Flow , 1999 .

[9]  Earl H. Dowell,et al.  LIMIT CYCLE OSCILLATIONS OF DELTA WING MODELS IN LOW SUBSONIC FLOW , 1999 .

[10]  Earl H. Dowell,et al.  Modeling Aerodynamic Nonlinearities for Two Aeroelastic Configurations: Delta Wing and Flapping Flag , 2003 .

[11]  Raymond E. Gordnier,et al.  Computation of limit-cycle oscillations of a delta wing , 2003 .

[12]  Earl H. Dowell,et al.  A theoretical and experimental investigation of the effects of a steady angle of attack on the nonlinear flutter of a delta wing plate model , 2003 .

[13]  Earl H. Dowell,et al.  Modeling the LCO of a Delta Wing Using a High , 2004 .

[14]  A. V. Balakrishnan,et al.  Nonlinear Aeroelasticity: Continuum Theory, Flutter/Divergence Speed, and Plate Wing Model , 2006 .