The CALIF3S-P2remics Software – An Application to Underexpanded Hydrogen Jet Deflagration

To assess explosion hazard, the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN) is developing the P2REMICS software (for Partially PREMIxed Combustion Solver) on the basis of the generic CFD solver library CALIF3S (for Components Adaptive Library for Fluid Flow Simulation). Both P2REMICS and CALIF3S are in-house IRSN softwares, released under an open-source license. CALIF3S-P2REMICS is dedicated to the simulation of explosion scenarii (explosive atmosphere formation, deflagration or detonation and blast waves propagation), for hydrogen as, more generally, for any explosive gas or gas/dust mixture. It is based on staggered space discretizations and implements fractional-steps time algorithms, well suited for massively parallel computations. A wide range of experiments is used for the software validation. Among them, we focus here on a free underexpanded hydrogen jet deflagration, performed in two steps: first, the hydrogen is released in air, up to obtain a steady jet (dispersion phase), then the deflagration is triggered. For the dispersion phase simulation, a notional nozzle approach is used to get rid of the description of the shocked zone located near the nozzle. Then a so-called turbulent flame velocity approach is chosen for the deflagration simulation. The computations allow to highlight the complex flow structures induced by the inhomogeneity fuel concentration in the jet. A large dispersion of results is observed, depending on the chosen correlation for the turbulent flame speed.