IGNITION OF HYDROGEN-AIR MIXTURES IN A CLOSED VESSEL AT ELEVATED PRESSURES

Experimental results obtained in studies of ignition and combustion in a closed vessel of hydrogen-air mixtures at initial pressures ranging from 1 to 9 MPa and initial hydrogen concentrations of 4-40 vol.% are presented. Experiments were conducted in vertical cylindrical chamber s 12 and 250 1 in volume, the mixture was initiated with an exploding wire at the chamber center. The measured maximum pressures and tempera ture are compared to the calculated equilibrium parameters of the comb ustion products of the mixtures studied. Mixtures containing more than 11% hydrogen ignited at the center of a 12 1 vessel burn completely, the pressure in these mixtures rises monotonically to its maximum valu e. The measured maximum pressures and temperatures are consistent with the appropriate calculated equilibrium parameters of the combustion p roducts. At lower hydrogen concentrations kinetic peculiarities of the hydrogen oxidation reaction show up which results in two-stage igniti on and incomplete hydrogen combustion.