Anshul Suri, Vilas Shinde, Jack J. McNamara, Datta V. Gaitonde
Panels encountering low-frequency loading due to proximal turbulent shock-wave boundary layer interactions (SWBLI) experience fluid structure interactions (FSI), with adverse and potentially catastrophic effects on high-speed vehicle performance. In certain parameter ranges, the feedback between fluid and structure is muted, and one-way analyses offer computational efficiency for rapid assessments of prescribed fluid load on the structural response (F→S) and vice versa, i.e., prescribed structural motion on fluid response (S→F). Both scenarios are examined here for a Mach 2 SWBLI over a 22.5o ramp, using Large-Eddy Simulations for the fluid and a finite-element model for the structure. Where possible, the literature on experimental observations and coupled simulations validate the appropriateness of the approach. In the F→S framework, the effects of precomputed turbulent surface pressures are examined on different panels; parameters varied include cavity pressure, boundary conditions (pinned/clamped), frequency alignment with structural modes, panel orientation, and location relative to the interaction. When placed near flow separation, panel responses exhibit distinct features including effective stiffening under elevated cavity pressure, emergence of asymmetric modes for oblique orientations, and mode selectivity influenced by spatial and spectral alignment with shock-induced features. When placed near reattachment, higher-order panel modes are excited, driven by shear layer impingement. In the S→F framework, the panel is placed near separation, with its motion conforming to mid-frequency scales. The flow response exhibits significant intermittency in separation/reattachment, reduced time-mean skin friction, attenuation of low-frequency content, and increase separation extent due to downstream movement of the reattachment point. Lagrangian modal analyses associate these effects with shock modulation by panel-induced intermittent shocklets.