Propellant casting process simulation in a small-scale solid rocket booster

Small-scale solid rocket motors have been extremely successful among propulsion industries in the last decades for improving the accuracy of thrust-time prediction in new motors in order to reduce the amount of experimental tests needed for the characterization of their internal ballistics behaviour. It is of common knowledge the fact that the ballistic response of solid rocket motors depends on several factors, among which the manufacturing process stands out. It is the grain that defines the quality of the propellant. Therefore, the thrust performance can be affected by heterogeneity of grain caused by inclusions (like bubbles, air gaps or cavities) and by the different concentration and orientation of the solid particles during the casting process. The main objectives of the present work are, firstly, the implementation of numerical simulations of small-scale solid motors casting process that helps to characterize the propellant and to study its rheological behaviour and, secondly, the acquisition of an insight of the burning rate anomaly phenomenon, also known as "Hump Effect", through the analysis of particle concentration. This work is divided into two parts: the former is focused on the challenge of bi-dimensional, multi-batch and 3D fluid dynamic simulations of the casting process and the other one focused on the tracking of the particles present inside the propellant. The software that has been used for this work is ANSYS Fluent. Post-processing codes have been implemented with MATLAB in order to obtain the concentration of the particles inside the rocket motor.