Aeroelastic Flap Free-Play Analysis Using a Harmonic Balance Approach
Aeroelastic limit cycle oscillation results are presented for a three-degree-of-freedom plunge, pitch, and flap structural model with flap free-play in a viscous transonic flow airfoil. A nonlinear frequency domain harmonic balance approach is used for the computational model. The Newton-Raphson approach solves the governing equations, and Brodyen’s method approximates the Jacobian matrix used in the Newton-Raphson approach, significantly reducing the computational approach. The authors have previously used the harmonic balance approach to model either the unsteady aerodynamics or the unsteady structural dynamics. In this case, we are now using harmonic balance to model both the unsteady aerodynamics and the unsteady structural dynamics. A strongly nonlinear limit cycle oscillation response trend is observed. The objective is to discern the nature of the limit cycle oscillation response and determine the computational requirements for accurately modeling it.
