Studying the Influence of Aluminium in ADN/HTPB based Solid Propellants

Ammonium Dinitramide (ADN) combustion has been the subject of great interest over the past few years due to consideration as a green oxidizer in solid rocket propellants. This study is focused on predicting the flame structure of an ADN/HTPB and ADN/HTPB/Al sandwich propellant. Initially, one-dimensional reactor modelling was carried out to implement the detailed chemical kinetics for AP and ADN monopropellant. Detailed understanding on the different combustion zones of ADN monopropellant was studied with implementation of one-dimensional reactor modelling. The results of one-dimensional studies were found to have good correlation with the previous literature. The sensitivity analysis was performed to understand the major species and dominant reaction in different burning zones. Initially, sandwich model was tested on AP/HTPB sandwich propellant and subsequently it was noticed that the findings were identical. The burn rate results of the AP/HTPB sandwich model were validated with the existing literature and were found to be in close match. Followed by this ADN/HTPB sandwich propellant was simulated using a detailed combustion chemistry using 215 reactions and 51 species were used to predict the flame structure across a wide range of pressure. The physiochemical reactions that occur during the combustion of ADN and HTPB are thoroughly examined by employing a complete gas phase combustion model. The computational framework is based on mass, species concentration, and energy conservation equations. For a pressure range of 0.6-6Mpa, the flame structure of the sandwich propellant in different combustion zones was studied. The simulations were also carried out with the addition of aluminum in a homogenized manner in ADN/HTPB sandwich. The gas phase temperature was found to increase with the addition of aluminum. The addition of nano aluminum was observed to have an influence on the flame structure and enhance the performance significantly.