3-component reactive flow modeling of nitromethane

The shock-to-detonation transition of nitromethane (NM) is typically characterized by the so-called Pop-plot, which gives the time-to-detonation versus input shock pressure. Recently, a model was developed (Combustion Theory and Modelling 25, 413-435 (2021)) using equations of state for NM and its products along with a two-component kinetic model. This model accurately reproduced legacy data with times-to-detonation ranging from 5 µs to 100 ns. However, such data is not sensitive to the NM chemical kinetic rates which occur on the 11 ns time scale of the NM reaction zone. Recent experiments (J. Appl. Phys. 124, 075901 (2018)) using 4 ns input shocks, where the time-to-detonation was 12 ns, were simulated with the two-component model and the agreement with experiment was poor, since the model predicted a decaying shock rather than a detonation, and it failed to predict several features at shorter times. These results indicate that a kinetic model with more than two components, that accurately reproduces the shorter-time processes in shocked NM, is needed to create an experimentally-validated theory that can predict the response of NM to shock waves and the interaction of NM detonations with external perturbations.