Induction zone studies in oxyhydrogen detonation waves at low initial pressures

Abstract

Detonation waves, with a laminar flow structure, were generated in oxyhydrogen mixtures at low initial pressures using a shock tube in conjunction with the two-dimensional nozzle technique of White. The motion and structure of these waves were studied by multiple-spark schlieren photography and piezoelectric pressure observations. Induction times t_i determined from the schlieren photographs, when plotted as [O₂]t_i against reciprocal absolute temperature, demonstrate that at any particular temperature in the range 950–2000°K the values of [O₂]t_i are a function of mixture composition. These observations are in general agreement with those of White on detonation waves and yield a value for the activation energy of the rate-controlling reaction H+O₂→OH+O which compares well with that obtained from shock wave studies. The pressure records provide confirmation of the existence of an induction zone having a constant pressure corresponding to the calculated causal shock pressure, and a duration which is in reasonable agreement with the schlieren-determined induction times.