CFD SIMULATION OF HYDROGEN RELEASE, DISPERSION AND AUTO-IGNITION IN ENCLOSURES

CFD simulations of auto-ignition of hot hydrogen flowing into a cylindrical enclosure where ambient air prevails were conducted. One-step global reaction was incorporated into ANSYS® software to simulate the chemical reaction between hydrogen and oxygen. Auto ignition was obtained for different inflow temperatures, agreeing with classical results of h2-o2 explosion limits, referred to as the "peninsula". Temperature range of the reaction zone lies below the value of the adiabatic flame temperature of a constant pressure process. This is due to the fact that although the enclosure is of constant volume, ignition takes place in a negligible fraction of the total volume; therefore the absolute pressure remains unchanged. Ignition delay decreases with the increase of the hydrogen inflow temperature. Moreover, their values are similar theoretical predictions.