Nonlinear aerodynamics and nonlinear structures interaction for F-16 limit cycle oscillation prediction

In this paper, a physically-rooted Nonlinear Structural Damping (NSD) model based on a generalized van der Pol model is integrated into ZEUS; a ZONA's Euler Unsteady Solver, to establish a Nonlinear Aerodynamics and Nonlinear Structures Interaction (NANSI) simulation tool for predicting limit cycle oscillation (LCO) amplitude. The parameter involved in the generalized van der Pol model is estimated from the flight test data of an F-16 with external stores configuration at a given flight condition. Once this parameter is identified, NANSI simulation is carried out to predict the LCO amplitudes at all flight conditions. Results show that the predicted LCO amplitudes for the F-16 Typical-LCO and Non-typical-LCO configurations correlate very well with the flight test data, demonstrating that the NSD is one of the key elements involved in the LCO of the F-16 with external stores configurations.