The Flow and Heat Transfer Behaviour of Liquid COMP-B3 in Slow Cook-off

In order to investigate the flow and heat transfer characteristics of COMP-B3 under thermal stimulation, a series of slow cook-off experiments were designed and conducted, encompassing different sample sizes and heating conditions. The internal temperature profiles were captured using a high-speed data acquisition system. Subsequently, the internal flow and heat transfer conditions of the liquid COMP-B3 were analyzed through numerical simulations employing a non-Newtonian flow model. The results demonstrated the presence of heat convection within the liquid COMP-B3, regardless of sample sizes or heating conditions. However, it should be noted that the occurrence of heat convection is not necessarily observed at the onset of melting. The overall cook-off process can be categorized into three phases: solid (with melting), thermal conduction, and thermal convection. If convection occurs prior to the self-heating reaction, the direction of the flow field within the liquid COMP-B3 experiences a reversal near ignition. Additionally, a predictive method for the flow behaviour inside the liquid COMP-B3 during slow cook-off is proposed. Rough estimates of the flow conditions can be made based on the charge temperature, the internal temperature difference, and the characteristic length. Importantly, these phenomena are theoretically applicable to a wide range of mixed melt-cast explosives, extending beyond COMP-B3. The results provide additional reference value for further investigations into the ignition characteristics of mixed melt-cast explosives under thermal stimulation.