Combustion of Mg-Zr based fuel rich propellant for air-breathing propulsion system

Burnign rate and energetics of Mg-NaNO3 and Zr-NaNQ(3) metal based propellants have been studied to elucidate their combustion mechanism and to understand the influence of addition of Zr particles on the combustion of Mg-NaNO3 system at different oxidiser levels. Results indicate that the burning rate of Mg-NaNO3 and Zr-NaNO3 propellants is higher at fuel-rich ratio due to high condensed phase heat release and decreases with increasing oxidiser content and shows a minimum value at stoichiometric ratio due to formation of metal agglomerates at the burning surface. However the burning rate and heat energy of Mg-NaNO3 compositions are higher than the Zr-NaNO3 compositions. On addition of Zr particles upto 20%, burning rate of Mg-NaNO3 at fuel-rich ratio further increases due to enhanced exothermic reactions at the burning surface resulting in the increase of surface heat energy, while at higher contents of Zr particles the burning sate decreases due to the lower heat energy content of Zr than Mg. At stoichiometric ratio of Mg-NaNO3 addition of Zr particles at all concentrations reduces the burning rate of Mg-NaNO3 due to enhanced metal agglomeration.