13. Vibration Reduction of a Compliant Panel Under Ramp-Induced Shock Wave/Boundary Layer Interaction Through Aeroelastic Tailoring

Experiments are performed in a Mach 2 wind tunnel to investigate the vibration of a compliant panel under a ramp-induced shock wave/boundary layer interaction (SBLI). The panel is made from brass shim stock of length and width 122 mm × 63.5 mm. It is located just upstream of a 20° compression ramp that creates a shock-induced separated flow, where the mean separation length scale is about two boundary layer thicknesses. The region of the separation shock foot is characterized by large pressure fluctuations. These increase vibration amplitudes of the higher panel modes and especially the second mode, which has an antinode near the shock foot region. This work uses aeroelastic tailoring to reduce the panel vibration induced by the large pressure fluctuations of the shock foot. A thin rib is attached in the spanwise direction to the lee side of the panel at the location of the mean separation line of the SBLI. Stereoscopic digital image correlation is used to obtain time-resolved, full-field displacement fields during wind tunnel runs. Three different panel configurations are tested. First, a baseline case is established with a plain panel of thickness h = 0.254 mm. Then the rib is attached to the panel using double-sided, viscoelastic tape. Finally, the rib is attached directly to the panel using an epoxy adhesive. The results show that adding the rib in either configuration reduces the overall panel vibration by about 50% but especially reduces the vibration of the second mode. The configuration with the tape adds mass and damping to the system and is more effective at vibration reduction than the configuration with the epoxy, which increases mass and stiffness.