A numerical model to analyze the thermal behavior of a propellant increment

The purpose of this study is to develop a numerical model of the thermal behavior of a propellant increment exposed to a variety of thermal environments and packaging conditions and predict the temperature distribution throughout the increment. The temperature distribution and bulk temperature of the propellant within the increment directly influence the burn rate and resulting pressure profile. The burn rate and pressure profile directly impact the range and stability of the munition which can result in a safety hazard if not properly accounted for. This study has two parts; first a numerical model is developed and second an experiment is designed and carried out to validate the numerical model. The experiment involves instrumenting a propellant increment with a series of thermocouples and heating it in a controlled laboratory environment. Temperature data is collected with a dedicated data collector and retained for analysis and validation of the numerical model. The numerical model accounts for variable thermal solar loading, various packaging configurations, and orientation. Initial results indicate that while there are points in the interior of the increment that come within 10 percent of the actual bulk temperature of the entire increment, the surface of the increment is not a good basis for prediction of the bulk temperature or temperature distribution within the increment. Additional analysis must be conducted to provide a viable estimate of the temperature distribution and bulk temperature of the increment based on the surface temperature in conjunction with knowledge of the exposure conditions.