Aeroelastic response of a thin panel excited by a separated shock–boundary layer interaction

Wind-tunnel experiments were conducted to investigate the effects of a separated shock–boundary layer interaction on the aeroelastic behavior of a thin panel in turbulent flow. A suite of traditional sensors and non-contact measurement techniques, including stereo digital image correlation (DIC), were used to characterize the operating conditions and structural response. The impact of the temperature differential between the panel and frame as well as cavity pressure on the panel response were explored. For a majority of the operating conditions, measured time histories of the panel dynamics revealed small-amplitude, forced oscillations about a stationary deformation. These deformations were due to the pressure fluctuations from the turbulent boundary layer and separated shock/boundary layer interaction. However, for a cavity pressure of 83 kPa and temperature differentials of [15, 17.2] K, the response transitioned to bi-stable, cross-well oscillations that were captured for the first time using DIC. The dynamic response was centered about the panel midpoint, coincident with the location of the shock-induced separation on the panel. Using several indirect tests, the intermittent, cross-well oscillations were characterized as potentially chaotic. As the temperature differential continued to decrease, the snap-through motions subsided and the panel response resumed a stationary behavior, albeit at a different deformation shape.