Combustion fundamentals on the melt layer of metalized propellants with surface stress evolution

Abstract

While progress has been made in the modeling of burning surface of solid propellants, the intricate interactions within the melt layer involving three distinct phases and multi-materials remain unresolved and present a formidable challenge. This study aims to present a comprehensive analysis on the combustion characteristics of metal-added propellants that considers reactive metal particles of random size. Three pivotal techniques are developed for 1) tracking the dynamics of two-phase interface with deforming material boundaries between reactive particle and binder, 2) incorporating the full stress field evolution within each particle, and 3) introducing the phase and composition identifiers to monitor the process of reaction via oxide cap formation, heat transfer between multi-materials, and agglomeration of metal oxide. To address the stability constraint on an explicit time integrator, both normal-size and scale-up simulations of heterogeneous particle packing models are developed using dimensionless numbers. The contours depicting pressure, temperature, stress, and material phase reveal the emergence and expansion of the melt layer, which includes isolated solid reactants with a multi-phase oxide cap and vaporized binder separated from the unburnt region. The quantitative weight fraction analysis delineates and provides insights on the three distinct sections, demarcated by predominant shifts in material phases. The results of the homogeneous model are compared to the reference data as well as heterogeneous model to validate the accuracy. The simulation successfully replicates the visual images taken from experiments without the need for complex mathematical models.