TEMPERATURE SENSITIVITY OF GRANULAR PROPELLANTS USING A CONDITIONED CLOSED BOMB

摘要

In this study, a temperature-conditioned closed-bomb facility was employed to determine the temperature sensitivity of granular M48 double-base propellant, as part of a larger study on the effect of initial temperature on the interior ballistics and overall performance of the U.S. Army's 120-mm mortar system. In order to determine the temperature sensitivity of the propellant over a broad range of applicable conditions, at least three test firings were performed at each of four different initial temperatures: -47, -12, 21, and 63℃ The pressure histories recorded from each of these firings were used to deduce the linear burning rate of M48 propellant as a function of pressure. In addition to the pressure measurements, non-intrusive acoustic emission technology was utilized in the closed-bomb tests to study the effect of initial temperature on the ignition delay of this propellant. Temperature sensitivity was found to be a constant equal to 037%/℃ with pressure and for initial temperature between -12 and 63℃. However, the deduced burning rate at -47℃ is greater than that at -12℃, leading to a temperature sensitivity of -0.07%/℃ for initial temperatures below -12℃. Propellant grain fracture seems an unlikely explanation for this observation because the burning rate and vivacity behavior at -47℃ mirrors that at the higher temperatures. The acoustic emission records have demonstrated an Arrhenius-type relationship between ignition delay time and initial temperature, which suggests that the propellant decomposition mechanism is not changing with temperature.