The kinetic characteristic features of the low temperature hydrogen oxidation during the induction period behind reflected shock waves

The experiments on the ignition of H2-O2 mixtures behind reflected shock waves were carried out. In these experiments the chemiluminescence of electronically excited OH* radicals (λ = 308 nm) at the early stage of the ignition induction period is studied over the temperature range of 800 < T < 1050 K at a pressure of 0.1 MPa. The OH* emission signal is measured for a time less than 1 ms, when the influence of physicochemical factors capable to influencing the homogeneous autoignition process such as flow turbulence in a boundary layer, various heterogeneous processes, and residual active particles is negligibly small. Significant difference between the ignition delay times derived from the pressure rise and sharp increase of the emission of electronically excited OH* radicals was experimentally observed. The experiments showed that the onset of OH* emission is always ahead of the time of pressure rise. Any regular dependence between the onset of OH* emission and the initial temperature behind the reflected shock wave T50 is not observed. This is indicative of a stochastic character of this process or hotspot ignition of the reactive mixture.