Shock Train - Flexible Wall Interaction in a Supersonic Isolator

An experimental investigation of the interaction between a shock train and a flexible wall was conducted in a Mach 2 direct-connect isolator at the Gas Dynamics Imaging Laboratory of the University of Michigan. The objective of the study was to assess the influence of wall compliance on the mean and unsteady characteristics of shock-train dynamics. The flexible-wall configuration, consisting of a 0.3 mm thick steel panel installed on the bottom wall of the isolator, was compared against an equivalent rigid-wall configuration under several back-pressure conditions. The results show that, for identical operating conditions, the presence of the flexible wall shifts the shock train upstream relative to the rigid-wall case. Additionally, power spectral density analysis reveals that the presence of the flexible wall significantly modifies the frequency content of the pressure fluctuations, producing stronger and more localized spectral peaks than those observed for the rigid case. The present results demonstrate that wall compliance has a measurable impact on both the mean structure and the dynamic behavior of shock trains and provide a first experimental characterization of shock-train/flexible-wall interactions in a supersonic isolator.