MULTIPHYSICS MODELLING OF VARIABLE CONFINEMENT COOK-OFF TEST (VCCT) EXPERIMENTS

摘要

The overall objective of this project was to determine if a finite elements based numerical code could be used to simulate heat transfer conditions in the small scale variable confinement cook-off test (VCCT). The COMSOL Multiphysics modelling software was selected to obtain a numerical description of the VCCT geometry and then employed to calculate the evolution of temperature within the energetic material samples and in the VCCT assembly itself. Heat losses to the environment were accounted for by considering natural convection and radiant energy, using COMSOL's built-in correlations to estimate the local heat transfer coefficient. Additional details such as solid-solid contact thermal resistance, melting enthalpies and temperature dependant physical properties were also included. Two cases were simulated: an inert material heating cycle, from room temperature to 180 °C, and a similar heating cycle on a Composition B sample. The analysis showed that simulated values were very close to experimental observations from thermocouples positioned at two locations in the inert sample. It is believed that an even closer agreement could be obtained by calibrating the calculated heat transfer coefficients using additional experimental data. As a whole, the study tends to confirm that a simulation approach could eventually be used as a screening tool to reduce the experimental workload associated with the assessment of thermal sensitivity of energetic materials.