Équations d’état pour les simulations d’écoulements issus de matériaux énergétiques condensés

Flow computations with condensed energetic materials involve sophisticated physical phenomena. The equation of state (EOS) is a key aspect governing the accuracy, robustness, and efficiency of computations. Some of the most popular EOS worldwide are Noble-Abel (NA) for interior ballistics and Jones-Wilkins-Lee (JWL) for the detonation products of explosives.However, these EOS present major issues when used in flow solvers. The main problems are related to the validity range which is often quite limited, the convexity range, and sophisticated formulations. These issues lead to inaccurate computations or computational failure. These observations motivated the present work.An alternative to the NA EOS is considered for interior ballistics applications. This EOS is based on a first-order virial expansion. Its predictions are more accurate than the NA EOS outside its adjustment range.A novel numerical method is developed to improve Mie-Grüneisen type EOS, such as JWL, in flow solvers. This method consists in using a simpler predictor EOS to close the flow model. Its parameters are then transported and relaxed to a target EOS. It improves the efficiency and robustness of computations significantly.An alternative to the JWL EOS is then examined. Based on thermochemical codes, the gas species of detonation products are governed by the Becker-Kistiakowsky-Wilson (BKW) EOS, and the condensed species by the Cochran-Chan (CC) EOS. Compared to JWL, the composition is now available and used in the computations. It extends the validity range and allows additional physical phenomena to be modeled. Thanks to the former thermodynamic relaxation method, extended at this level to the BKW-CC EOS, the computational cost remains reasonable.