Measurement and Modeling of Pressure -Driven Transient Burning of Solid Propellants

Abstract

In the modeling section of this study, two transient heterogeneous propellant combustion models, applicable to fine oxidizer composite propellants, are examined. The "surface accumulation model" supposes that components accumulate in a layer at the surface. Each component reaches an equilibrium concentration inversely proportional to its burning rate. The "double reaction layer model" supposes that a molten binder layer covers the propellant. The oxidizer gasifies underneath the layer, while the binder gasifies at the surface. The double reaction layer model qualitatively produces features observed in experimental laser-recoil response function data: a sharp resonance peak accompanied by a shift from negative to positive phase. The surface accumulation model does not produce these features. The presence of time delay terms---the time lag is caused by heat conduction through the binder layer---in the double reaction layer model accounts for the sharp resonance peak. The frequency of the peak produced by the model is lower than what is observed in the data; this discrepancy is attributed to uncertainties in the properties of the binder layer.