New Directions in Multiphase Flow Interior Ballistic Modeling

摘要

Over the past two decades, several two-phase-flow interior ballistic codes havebeen developed. Generally, they have treated ignition-induced pressure waves as a hydrodynamic problem which arises from the ignition stimulus, the propellant geometry, the path of flamespreading in the propellant bed, and the interaction of charge and chamber. Ignition and combustion have been treated as a simple process, with convectively-driven inert heating of the propellant until a surface-temperature criterion is reached, at which time an aP superscript n burning law describes the propellant surface regression, and all of the energy contained in the burned propellant is released immediately. The effects of propellant grain fracture, caused either by grain stress due to propellant bed compaction or by impact with fixed boundaries, has been outside the scope of the several codes. While the codes have incorporated interphase heat transfer and drag, they have been called inviscid, as the conservation laws are formulated to neglect the efforts of viscosity and heat conduction in the gas phase. This report describes, for the NOVA family of codes, (a) the recent inclusion of finite-rate chemistry and grain fracture, (b) planned efforts to improve the propellant near-field combustion model further, and (c) ongoing efforts to formulate a viscid/inviscid model to permit a linkage of effects with widely differing scales of heterogeneity. Keywords: Interior ballistics; Modeling; Kinetics; Viscosity. (jhd)