Modeling of Hydrogen-Air Detonations in the TONUS CFD Code and Its Application to the FLAME F-19 Test

In severe accident management, the ability to predict pressure and thermal loads resulting from hydrogen combustion is important since they may threaten containment integrity. In computational modeling, different combustion regimes have to be accounted for and state-of-the-art techniques developed for reliable analysis. In the present study, the focus is on computational fluid dynamics code validation for reactive flows in the detonation regime. The FLAME hydrogen combustion test F-19 performed at the Sandia National Laboratories has been simulated by using the gas detonation model implemented in the TONUS CFD code which is developed by CEA and IRSN (France). In this model the reactive Euler equations are solved and the reaction rate is obtained by the Arrhenius global rate equation. Several simulations were run in order to examine the effect of modifying the parameters of the chemistry model. A mesh convergence study was performed for the purpose of finding out the necessary mesh resolution which could capture the detonation propagation with adequate accuracy. In addition, Chapman-Jouguet post-shock equilibrium conditions and the ZND detonation structure for the present gas mixture were examined by chemical kinetics calculations. The CFD simulation results were compared to the test results and the Chapman-Jouguet post-shock conditions. It was observed that the computational results differ from the C-J results with the C-J velocity being slightly exceeded. The model parameter study showed that it is not possible to significantly affect the flame propagation by adjusting the model parameters.