Ignition and Flame Propagation in Narrow Channels of Solid Propellant

Future direct-fire gun systems will require solid propellant at high loading density, which can be achieved with propellant in slab-type geometry such as radial discs, concentric wraps, or scrolls. Adjacent propellant slabs will form porosity as narrow sheet-like channels (with entirely different permeability than bundled sticks or cylindrical grains). Successful functioning of the charge requires rapid ignition and unimpeded flame propagation throughout this system of channels. The present investigation is concerned with characterizing the fundamental ignition and transient combustion behavior of energetic materials when packed in such configurations. A special laboratory apparatus was designed to isolate two propellant channels and allow direct comparison of the influence of variable gap width, wall composition (inert or JA2 here), and channel end closure. Diagnostics include multiple pressure time histories along each channel length and high-speed cinematography of the propagation of flame. Results are presented for several channel configurations, showing influence of JA2 or plastic wall material, gap widths of 0-0.89 mm, and channel downstream ends either open or closed. The original document contains color images. All DTIC reproductions will be in black and white.