Experiments on Supersonic Fluid-Structure Interaction in Transient Flow Fields

Fluid-structure interaction (FSI) is a key problem in the design of supersonic and hypersonic vehicles yet remains a challenge for current modelling approaches. It is especially difficult to obtain reliable predictions for cases with complicated flow fields, e. g. with shock-wave/boundary-layer interaction (SWBLI), or for transient changes in a flow field such as they occur during the course of a vehicle trajectory. To contribute to the understanding of such problems and to provide reference data for numerical modeling, we conducted experiments on supersonic FSI in combination with SWBLI in the wind tunnel TMK at DLR, Cologne. For such studies, the unique FSI setup at the wind tunnel TMK enables obtaining transients of the inflow conditions by adjusting the Mach number and transients in the incident shock angle by adjusting the shock generator during the wind tunnel run. In these experiments, we obtained large-amplitude self-excited oscillations of thin metallic panels. These dynamics were studied regarding both their sensitivity to small changes in the flow field and also larger transients in Mach number and incident shock angle. Measurements of the structural dynamics were conducted by using capacitive distance sensors inside the wind tunnel model and a Digital Image Correlation (DIC) system. The experiments were conducted within project HYRECA in collaboration with the Air Force Research Laboratory (AFRL) Structural Sciences Center (SSC).