Effects of Hydrogen-Air Gas Mixture Volume and Initiation Type and Energy on the Propagation of a Spherical Flame Front

The investigation considered a spherical flame front propagating in free space filled with a hydrogen-air mixture containing 15 % hydrogen. The experiments were conducted inside latex shells. We initiated combustion in the centre of the volume, using either a 1 mJ spark or a nichrome wire explosion releasing 5 J of energy. In the case of the 7 m³ and larger shells, we recorded video data on the flame front using an InfraTec ImageIR 8320 infrared camera featuring a 2.0--5.7 μm spectral ranges and a rate of 300 frames per second. In the case of the 0.003 m³ and smaller shells, we visualised the processes by means of an IAB-451 schlieren system. We recorded these images using a Videosprint G/2 visible-wavelength camera at a rate of 1000 frames per second. We identified the differences in flame front acceleration dynamics for the same combustible mixture composition and flame initiation energy. We found that the distribution function specifics concerning the pre-exponential factors in the power law of flame front acceleration indicate that individual random perturbations have a considerable effect at the initial stage of quasi-spherical flame front formation. We compared flame front propagation for the cases when the initiation energy was 1 mJ and 5 J respectively and determined that the initiation energy also affects the process

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