A Theory for the Influence of Solid Heterogeneity on L* Instability

Based on a previously Proposed “sideways sandwich model”. L* instability of a heterogeneous propellant is investigated. It is shown that strictly speaking the stability limit for a heterogeneous propellant is the same as that of a homogeneous propellant whose properties are the space-average of those of the heterogeneous propellant. In addition it is found that under suitable conditions heterogeneity can falsify the stability limit and produce a stabilization effect. When the heterogeneity frequency of the propellant coincides with the characteristic frequency calculated from the homogeneous theory, the analysis predicts linearly growing L* oscillations at the homogeneous L* stability limit, with a consequent intensification of the instability. The theoretical predictions offer some explanations for dual-frequency phenomena in L* burners.