Model for Prediction of Double-Base Propellant Burn Rate, Including Cross-Flow Effects

A model permitting the prediction of mass burning rate of uncatalyzed NG/NC double-base propellants as a function of cross-flow velocity, pressure, and formulation heat of explosion has been developed. Two cross-flow model variants, differing in assumptions regarding the penetration of cross-flow induced turbulence into the fizz zone, were examined. In the first variant, the fizz zone was treated as being sufficiently structured to prevent turbulence penetration. This model variant was found to result in serious underprediction of cross-flow effects. In the other variant, the fizz zone was treated as a gas in terms of its fluid dynamic behavior, with resultant turbulence amplification of transport properties in both the fizz and dark zones. With this approach, reasonably good agreement between predicted and measured burning rates over a wide range of cross-flow velocities was obtained. Under zero-cross-flow conditions, the model was found to give good agreement with data for burning mass fluxes in excess of 0.5 g/cm-s without introduction of a pressure-dependency for surface/subsurface condensed-phase heat release. Inclusion of pressure dependency in this term permitted extension of the region of good agreement between data and theory down to 0.3 g/cm-s.