Conservative common-refinement coupling for compressible fluid–structure interaction in solid rocket motor ignition

This study develops a three-dimensional multi-physics framework for simulating ignition transients in solid rocket motors (SRMs), explicitly resolving the coupled interactions of transient compressible flow, heat transfer, combustion, and structural dynamics. The methodology introduces a weighted residual formulation based on common-refinement discretization for fluid–structure interface data transfer, which rigorously enforces conservation laws while minimizing numerical errors across non-matching meshes. Temporal synchronization across physical domains is achieved through predictor–corrector iterations, ensuring stability in strongly coupled simulations. Validation employs a supersonic shock-panel interaction benchmark, where data exchange tests between mismatched fluid and solid surface meshes confirm the method’s accuracy and robustness properties. Quantitative comparisons with experimental measurements and reference numerical solutions demonstrate its accuracy in handling compressible fluid–structure coupling. Application to an SRM ignition case captures coupled flow evolution, flame propagation, and propellant structural responses. The coupled simulation reveals distinct flame spreading patterns and dynamic burning surface evolution, directly linked to chamber pressure variations unobserved in single-field analyses. Furthermore, the results identify the propellant’s viscoelastic behaviour and ignition-induced structural vibrations, underscoring the necessity of multi-physics coupling to resolve transient ignition mechanisms. This work establishes a computational foundation for analyzing critical interactions governing SRM ignition dynamics.