A general thermal explosion criterion application to initiation by imbedded wires
A thermal explosion criterion recently published by the author (see ibid., vol.11, 239 of 1967) is used to obtain general solutions for the explosion/ignition delay of an exothermic material surrounding a heated wire which is long and a good thermal conductor. The case of d.c. heating is treated first and in greatest detail. Equations for explosion delay and explosion temperature are derived, which show how these variables depend on the initial conditions, the properties of the wire and the explosive, wire size and the heating rate. Predicted explosion times are shown to agree well with those obtained by numerical integration of the complete set of differential equations which define the d.c.-wire problem. A Laplace transform technique is used to derive an explicit approximation to the wire temperature when the heating rate varies with time. The use of this approximation is illustrated for a heating function proportional to τ exp (-λτ), where τ is non- dimensional time