Influence of Discrete Sources on Detonation Propagation in a Burgers Equation Analog System

TL;DR

This study uses an analog system based on the Burgers equation to explore how spatial discreteness of energy sources affects detonation wave propagation, challenging traditional homogeneous assumptions and showing comparable average velocities.

Contribution

It introduces an analytic approach to model detonation in discrete, heterogeneous media using Burgers equation analogs, without finite difference methods.

Findings

Average shock velocity matches classical CJ velocity in homogenized media

Discrete sources can produce detonation-like waves similar to homogeneous cases

Results suggest CJ criterion may apply to highly heterogeneous detonations

Abstract

An analog to the equations of compressible flow that is based on the inviscid Burgers equation is utilized to investigate the effect of spatial discreteness of energy release on the propagation of a detonation wave. While the traditional Chapman-Jouguet (CJ) treatment of a detonation wave assumes that the energy release of the medium is homogeneous through space, the system examined here consists of sources represented by $\delta$-functions embedded in an otherwise inert medium. The sources are triggered by the passage of the leading shock wave following a delay that is either of fixed period or randomly generated. The solution for wave propagation through a large array ($10^3$-$10^4$) of sources in one dimension can be constructed without the use of a finite difference approximation by tracking the interaction of sawtooth-profiled waves for which an analytic solution is available. A detonation-like wave results from the interaction of the shock and rarefaction waves generated by the sources. The measurement of the average velocity of the leading shock front for systems of both regular, fixed-period and randomized sources is found to be in close agreement with the velocity of the equivalent CJ detonation in a uniform medium wherein the sources have been spatially homogenized. This result may have implications for the applicability of the CJ criterion to detonations in highly heterogeneous media (e.g., polycrystalline, solid explosives) and unstable detonations with a transient and multidimensional structure (e.g., gaseous detonation waves).