HAM Explosion in Unconstrained Spherical Volume

The compression wave amplitude was constant inside the burning volume and corresponded to the combustion velocity. Outside the burning volume the pressure dropped in proportion to The compression phase was always followed by a rarefaction phase with less duration than the compression phase, but with increased amplitude. The DDT process was not recorded in any of the experiments. 

At the anticipated laminar flame velocity 2.39 m/s and combustion products expansion factor a = 7.26 (no turbulent effect or flame curvature) a visible velocity of 17.35 m/s was predicted. 

All the aforementioned parameters are far from those of a detonation, even if we compare them with the sound speed in the fresh HAM mixture (397.3 m/s). Based on the photo of the burning volume (Fig. 9.21) the measured thickness of the spherical turbulent flame was equal to several meters [12]. 

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