Recent DDT simulations and criteria based on experimental and numerical results for hydrogen safety studies. HGF-H2 project: Part 2

In this report, we will first briefly describe the phenomena, underlying mechanisms and necessary criteria of DDT, then summarize the experimental work on hydrogen explosion performed at the SWL of RWTH Aachen. Then we will explain the CFD codes SHOCKIN and AIXCO as well as the applications in the simulation of DDT processes. Studies performed at the SWL include three topics: 1) self-ignition phenomena; 2) DDT mechanisms in axis-symmetric geometry with periodic obstacles or a single obstacle; and 3) detonation formation at the entrance to narrow gaps. A database of ignition delay times and schlieren records has been set up for hydrogen-air-steam/CO2 mixtures. Excellent photographs concerning shock reflections and ignition were produced providing good materials for the validation of computer codes. (orig.)