Combustion mechanism of double-base propellant containing nitrogen heterocyclic nitroamines (I): The effect of heat and mass transfer to the burning characteristics

In order to evaluate the actual pros and cons in the use of new nitroamines for solid rocket applications, the combustion properties of double-base propellants containing nitrogen heterocyclic nitroamines such as RDX, TNAD, HMX and DNP are experimentally investigated by means of high-speed photography technique, thermogravimetry (TG) and differential scanning calorimetry (DSC). It was indicated that DNP and TNAD can yield a lower pressure exponent than that of RDX and HMX, especially, TNAD-CMDB can give plateau burning at higher pressure (> 12 MPa) with higher burning rates (n < 0.2, r > 30   mm s^{- 1}) than that of RDX and HMX. It was also concluded that the rate of change in space of the temperature gradient is negligible for these propellants and the rate of mass diffusion is assumed to be small compared with the rate of mass convection. Furthermore, the reaction of CH₂O + NO₂ → CO + NO + H₂O is probably the most important one in the foam layer of the propellants containing nitrogen heterocyclic nitroamines and the thermodynamic phase transition consisting of both evaporation and condensation of NC, HMX, TNAD, RDX and DNP, are considered to provide a complete description of the mass transfer process.