Model of Impact Ignition and Explanation of Critical Shock Initiation Energy. Rudiments

Abstract

It is shown that the critical shock initiation energy relationship of Walker and Wasley corresponds to the Hugoniot energy delivered during the shock ignition of the material. This relationship thus defines the functional form of the ignition delay time under conditions that the relationship is valid. The concept of a special energy fluence is not relevant. The rudiments of a new shock ignition model are postulated. This model attributes the ignition delay time to be controlled by the time it takes the hot reaction products in small hot spots that are initiated near the shock front to heat and ignite the adjacent solid material, so as to set up a spreading grain burning reaction in the material. The model is qualitatively consistent with the functional form of the critical energy equation under certain conditions, but the ignition behavior is not restricted to that form. Under conditions that the initiating hot spot concentration becomes sufficiently large, the initiation event becomes essentially homogeneous in nature.