Hydrogen explosion in ITER: Effect of oxygen content on flame propagation of H2/O2/N2 mixtures

The present work is a research aimed at acquiring data useful to support the assessment of H2/O2/N2 mixtures risk explosion in ITER. This paper reports laminar flame properties: maximum combustion pressure (PMAX), deflagration index (KG) and laminar flame speed (SL°) of H2/O2/N2 mixtures over a wide range of initial conditions ( X H 2 = 0.1 – 0.6 ; N2/O2 = 0.66–9; Tini = 303–343 K; Pini = 50–100 kPa). This study was performed in a stainless steel spherical chamber (0.056 m3 volume) equipped with an electric central ignition. A high speed imaging system is used to visualize the outward flame propagation and deduce SL°. The evolution of the pressure inside the vessel during the combustion is monitored. From this temporal evolution of the pressure, PMAX and KG are deduced. Laminar flame speeds were evaluated using 3 different detailed kinetic mechanisms from the literature [13–15]. The comparison between simulated and experimental values was used to select the most suitable one [15] to calculate the global activation energy of these mixtures. These simulations were performed using COSILAB®.