Detonation propagation from a cylindrical tube into a diverging cone

Abstract

The characteristics of the propagation of a detonation from a cylindrical tube of constant cross section into a diverging cone were experimentally investigated using the smoked-foil technique for three explosive gas mixtures: C2H2+2.5O2, 2H2+O2+4.5Ar, and C2H4+3O2+0.44N2. The initial pressure and the cone enlargement angle were varied as governing parameters. The results were summarized in terms of the ratio between the inner diameter of the cylindrical tube through which a detonation initially propagated and the detonation cell width d/λ and of the cone enlargement half angle θ. Four patterns of detonation propagation were observed in the diverging cone: continuous propagation, re-initiation on the cone wall, re-initiation apart from the cone wall, and failure. The obtained results were qualitatively consistent with past experimental results reported by other researchers. However, quantitatively, the obtained results were dependent on the explosive gas mixtures, particularly on the so-called critical tube diameter. Actually, when the critical values of d/λ against detonation failure were normalized by that corresponding to θ = 90°, a single curve unifying all data to some degree was obtained. In addition, some characteristics of the detonation behavior in the diverging cone were explained by simple models.

Keywords

• detonation
• diverging cone
• failure
• smoked foil
• critical tube diameter