Structure of temperature distribution in steady-state burning of a ballistite powder

Summary

• 1. Using tungsten-rhenium thermocouples we have obtained a complete temperature distribution for steady-state burning of nitroglycerine powder in the pressure range 5–150 atm at an initial powder temperature of 25° C.

• 2. We have found the surface temperature of the burning powder T_S as a function of pressure. This temperature is 200° C at p=3 atm and 300° C at 10 atm. The rate of growth of T_S decreases with pressure. A temperature of 400° C is reached at p=50 atm and 450° C at 120–150 atm.

• 3. The temperature distribution in the condensed phase is 1.5–2 times broader than the Michelson distribution, which can to a large extent be attributed to the increase in the thermal conductivity of the powder with temperature.

• 4. The multizonal character of the temperature distribution in the gas phase has been confirmed. With increase in pressure the vapor-smoke-gas zone approaches the surface more slowly than the flame zone.

• 5. The amount of heat released in the reaction layer of the condensed phase increases from 60 at 5 atm to 130 cal/g at 150 atm. The fraction of heat supplied to the condensed phase from the gas phase is 15–20% of the total amount of heat released in the condensed phase.

• 6. The heat release in the smoke-gas zone and the flame zone also increases with increase in pressure: in the former from 300 (5 atm) to 360 cal/g (75 atm), in the latter from 220 (20 atm) to 320 cal/g (75 atm).