Modeling the LCO of a delta wing 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 degrees) and for various flow speeds. Theoretical results are calculated for two different root chord boundary conditions, i.e. fully clamped 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. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
