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Accueil du site > Thèmes de recherche > Combustion & systèmes réactifs > 1.6 Dynamics of chemical explosions > 1.6.1 Fundamental explosion properties

1.6.1 Fundamental explosion properties

1.6.1.1 Methane – hydrogen and natural gas – syngas mixtures
Among the fundamental properties of combustion, SL° is very important not only as a tool of chemical kinetic validation (see §2.1.1) but also because it leads to other parameters very important in chemical explosions : flammability limits, maximum overpressure rise, appearance of instabilities, Markstein length, etc. By using a detailed kinetic mechanism coupled with the experimental data, the Zeldovich number can then be derived. These fundamental studies are mandatory in order to analyze the different regimes a flame can undergo (see §2.2.2). These parameters have been determined for different hydrogen based mixtures for a wide range of initial conditions in terms of pressure, temperature and equivalence ratios. These studies have been carried out in collaboration with IRSN for H2 – air – water vapor (2005-2009 ; 2009-2012) and INERIS/IRSN for natural gas and syngas mixtures (2008-2011). Moreover, by using high pressure shock tubes and detonation tubes, auto-ignition delay times and dynamic parameters of detonation have been determined in the case of H2-CH4-air mixtures. These data along with the aforementioned ones have been used in order to validate a kinetic mechanism applicable to detonation evaluation (TH26, ACL12 ; ACTI24-25, ACTI61, COM1, COM29, COM31 ; AFF67, AFF68, AFF70).

1.6.1.2 Hydrogen – N2O mixtures
Silane-nitrous oxide mixtures are widely used in some industries such as semiconductor manufacturing and also constitute a safety hazard in nuclear waste storage. Since the decomposition of silane is faster than that of N2O and involves the formation of H2, the H2-N2O system might be an important sub-system of the silane oxidation mechanism. A fundamental study has been performed in order to assess the explosion properties of such mixtures and auto-ignition delay times, laminar flame velocities and detonation properties have been determined (TH28 ; ACL48, 65 ; ACTI46, 47, 56, 65, 73, 74, 75 ; AFF5, 62).

1.6.1.3 Hydrogen – dust mixtures
A new study has been initiated in collaboration with IRSN (2010-2013) which is aimed at a better assessment of the explosion hazards in the International Thermonuclear Experimental Reactor (ITER). During normal operating conditions, several kilograms of dust (graphite, tungsten and beryllium) can be produced due to the erosion of the ITER chamber walls. A cloud of combustible particles can then be formed and it is critical to assess its explosive properties such as the maximum overpressure, the maximum pressure rise rate in case of combined mixtures of hydrogen and dust. In the framework of a PhD thesis these parameters are assessed as well as the flammability limits of these mixtures for various dust concentration, average particle size, and initial temperature and pressure (AFF73).