Experiments on Supersonic Fluid-Structure Interaction for an Incident Shock Configuration in the Wind Tunnel TMK

Abstract

Fluid-structure interaction (FSI) is a crucial problem in the design of supersonic and hypersonic vehicles but poses a substantial challenge for the modelling capabilities currently available. Cases that include shockwave/boundary-layer interaction (SWBLI) are particularly challenging as the dynamics of such a flow field are not fully understood for cases with a rigid wall but typically include substantial low-frequency pressure fluctuations in the order of 1 kHz which is similar to the range of typical eigenfrequencies of vehicle surface structures. To improve understanding of such problems, we conducted experiments on supersonic FSI in combination with SWBLI in the wind tunnel TMK at DLR, Cologne. The experiments were conducted within project HYRECA in collaboration with the Air Force Research Laboratory (AFRL) Structural Sciences Center (SSC). We obtained large-amplitude self-excited oscillations of an elastic panel. Furthermore, the possibility of modifying the dynamic behavior of the structure by changing the Mach number during the wind tunnel run was explored. For the first time in the literature, the transient flow conditions were observed to induce drastic changes in the panel dynamics. Measurements of the structural dynamics were conducted both by using capacitive distance sensors inside the wind tunnel model and a Digital image correlation (DIC) system. The latter recorded full-field time resolved surface deformation data. The results obtained in the present experiments are relevant and applicable both to supersonic and hypersonic configurations.