Investigation on Combustion Reaction Evolution Model of Charge with Mass Inertia Constraint via Non-shock Ignition

It is of great significance to develop an engineering model based on the physical mechanism of non-shock initiation reaction of structural charge, which can be used to describe the reaction evolution process and quantify the reaction intensity for evaluating the weapons and ammunition safety. Currently, some models describing the charge reaction evolution were one-dimensional pressurization of burning crack and charge burning crack network, but these models had many assumptions, and some restrictive problems, such as non-considering of the cavity expansion volume, and the unclear burning crack propagation coefficient. Therefore, a constrained charge combustion reaction evolution model was established with fracture toughness and reaction pressure as the main parameters based on the main control mechanism of charge reaction crack propagation in this study, which can describe the combustion gaseous product pressurization and shell constraint strength during combustion evolution. Relevant details for the control model establishment process were given. The model reliability of confined charge reaction combustion evolution was verified via the experiments of PBX-3 (87% HMX) explosive combustion reaction evolution under mass inertial confinement. The mass velocity-time was recorded by PDV (Photonic Doppler Velocimetry) transducers, the pressure-time profiles was recorded via pressure transducers and the experimental process was captured via high-speed camera. Above experimental results were compared with calculated results from the control model proposed in this work. The results show that the reaction pressurization process calculated via the model is roughly consistent with the pressure increasing trend in the experiment (calculated by the mass velocity), and the control model considering the structural venting effect can reflect the competition mechanism between combustion gas pressurization and venting in the pressure increasing process, and the relationship between the pressure increasing trend and the vent coefficient is in line with the mechanism analysis expectation. The results can provide support for deepening the understanding of accidental explosives combustion reaction evolution mechanism.