Accession Number : ADA322856

Title :   Ignition in Solid Energetic Materials Due to Electrical Discharge.

Descriptive Note : Final rept.,

Corporate Author : NAVAL SURFACE WARFARE CENTER INDIAN HEAD DIV MD

Personal Author(s) : Lee, Richard J.

PDF Url : ADA322856

Report Date : 25 OCT 1996

Pagination or Media Count : 100

Abstract : Fatal mishaps have been blamed on accidental ignition of solid rocket propellant by electrostatic discharge (ESD). Despite study of this problem since the first incident in 1985 involving a Pershing II motor stage, our understanding of ESD ignition remains limited. To determine the physics of electrically-induced ignition, the temperature, density, and size of electrical arc channels have been quantified during electrical discharge experiments on a composite solid propellant To simulate the discharge in ESD scenarios involving insulated motors, short duration electrical discharges (50 to 400 ns) were employed. The lowest ignition energy for these experiments was 160 plus or minus 1.4 mJ. Measurements from pressure transducers and infrared detectors were consistent with a relatively slow thermally-induced reaction rather than prompt ignition from a shock wave. A high-speed framing camera observed expansion of the arc channel as electrical energy was deposited. An analytical model was adapted to predict arc channel expansion for various discharge profiles. An ignition model based on energy transport, via radiation and thermal conduction, from the plasma to the surrounding energetic constituents is proposed. A one-dimensional thermal-chemical kinetics code, XCHEM, was used to demonstrate the importance of radiation in the ignition model.

Descriptors :   *MATERIALS, *SOLIDS, *ELECTRIC DISCHARGES, *IGNITION, *ENERGETIC PROPERTIES, *SOLID ROCKET PROPELLANTS, THERMAL PROPERTIES, MATHEMATICAL MODELS, DENSITY, TEMPERATURE, PRESSURE TRANSDUCERS, INSULATION, ONE DIMENSIONAL, SHOCK WAVES, ENERGY TRANSFER, CHEMICAL REACTIONS, HEATING, THERMAL CONDUCTIVITY, ELECTRICITY, INFRARED DETECTORS, KINETICS, MOTORS, ELECTROSTATICS, ELECTRIC ARCS, ACCIDENTS, COMPOSITE PROPELLANTS.

Subject Categories : Miscellaneous Materials
      Combustion and Ignition
      Physical Chemistry
      Ammunition and Explosives
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE