Fully coupled fluid–structure interaction of diaphragm rupture in high-pressure-ratio shock tunnels

Shock tunnels are indispensable facilities for hypersonic aerodynamic experimentation. Within these systems, the diaphragm plays a pivotal role, as its rupture process critically influences shock wave generation quality, experimental repeatability, and facility reliability. A thorough understanding of diaphragm rupture dynamics is therefore essential for optimizing shock tunnel design, improving experimental accuracy, and ensuring operational safety. To address the complex challenge of fully coupled multiphysics analysis in high-pressure-ratio shock tunnels, this study introduces a high-fidelity, three-dimensional, fully coupled Fluid-Structure Interaction (FSI) simulation framework. This framework seamlessly integrates the Dual Conservation Element and Solution Element (Dual-CESE) method, the Immersed Boundary Method (IBM), and the Johnson-Cook (J-C) material constitutive and failure model. The combined approach enables synchronized simulation and analysis of the entire diaphragm rupture sequence—including pre-deformation, crack initiation and propagation, and fully developed petaling deformation—alongside the formation and evolution of the associated supersonic flow field. The simulation results show strong agreement with experimental observations, with the post-rupture geometric morphology accurately replicated and a shock wave velocity deviation of only 2.55% from experimental measurements. The study uncovers the dynamic failure mechanisms, revealing that nonlinear pressure loading initiates cracking within the diaphragm. It further elucidates how the nonlinearly coupled interactions between petaling dynamics and fracture morphology directly impact shock wave formation and evolution. This computational framework provides a novel and robust methodology for advancing shock tunnel design and conducting comprehensive reliability assessments.