Physics-constrained identification of near-flutter aeroelastic damping from finite records

Abstract

Near flutter, modal frequency can be well resolved from accumulated phase while the sign of a small modal growth rate remains uncertain because the response envelope changes only weakly over a finite record. This work tests whether a validated physical relation between frequency and damping can exploit the better-resolved phase information to improve near-flutter stability identification. A coupling-audited SU2 Euler campaign for a modified Isogai-parameterized NACA 64A010 section at Mach 0.85 is subjected to systematic grid and temporal verification, multichannel critical-pole tracking, bootstrap trajectory closure, finite-record information analysis, and nonlinear Monte Carlo validation. The temporal study shows that 50 steps per structural period predict the wrong damping sign although frequency is already close to the finer solutions. The verified critical trajectory gives a flutter-speed index of 0.537665 and a local frequency-to-damping slope of 3.754. Restricting a free pole estimate to this trajectory gives an approximately 3.89-fold damping-precision gain, reproduced by Monte Carlo with a median RMSE gain of 3.915. At a representative operating offset and 30 dB amplitude SNR, the minimum tested record exceeding 95% correct-sign probability decreases from 15 to 5 cycles. Physically validated pole trajectories can therefore substantially reduce the observation time required for reliable near-boundary aeroelastic stability identification.