Experiments on a thin panel excited by turbulent flow and shock/boundary-layer interactions

An experimental methodology was designed to study the effects of turbulent flow and shock/boundary-layer interaction (SBLI) on the postflutter response of a thin, buckled panel. The approach combines a systematic testing strategy with state-of-the-art full-field, noncontact measurement techniques, including pressure-sensitive paint, three-dimensional digital image correlation (DIC), and schlieren imaging. These measurements, combined with traditional sensors, were used to characterize the loading conditions and the structural response. The thermally buckled panel experienced bistable, cross-well oscillations with cavity pressure modulation for turbulent flow conditions. This response was characterized as chaotic using several conventional criteria. As the temperature differential between the frame and panel decreased, the panel response transitioned to periodic. For the first time, shock-induced limit cycle oscillations (LCOs) were also measured using DIC. In the presence of an attached SBLI, the dynamic response was centered about the three-quarter chord. As the strength of the SBLI increased, the LCO initially subsided and then reappeared near the midchord for the strongest shock considered.