Burning Behaviour of ADN Formulations

Abstract

The application of ADN for an effective oxidizer of propellants and explosives requires a detailed knowledge of the burning behaviour. The physical and chemical mechanisms of the combustion depend on pressure. Especially profiles of temperature and species in the flame are important to design propellant formulation of high performance and low signature of the rocket plume. In the presented study, pure ADN and ADN/paraffin mixtures were investigated as strands in an optical bomb at pressures of 0.5 MPa to 10 MPa. The application of non-intrusive combustion diagnostics for the investigation of fast burning energetic materials allowed the measurement of burning rates and profiles of temperature and gas components at various distances above the burning propellant surface. The burning rate was determined by using a video system and a special frame analysis. The acquisition and analysis of emission spectra in the UV/VIS allowed the investigation of rotational temperatures, the determination of particle temperatures and the identification of transient flame radicals. The vibrational temperatures of final combustion products resulted from band spectra emitted in the near and mid infrared spectral range. Burning rates of 5 mm/s to 70 mm/s were recorded showing a mesa/plateau-effect in the pressure range of 4 MPa to 7 MPa. The UV/VIS spectra indicated an emission from OH, NH and CN radicals. The strong emission of OH bands of the ADN/paraffin mixture allowed the investigation of rotational temperatures with a mean value of 2700 K which is closely below the adiabatic flame temperature of 2950 K. Additionally, one-dimensional intensity profiles of the flame radicals were measured. As combustion end products H2O, CO, CO2 and NO were found. NO could only be detected at a distance up to 2 mm above the propellant surface. The measured CO/CO2 fraction was higher as 10/1. Water could only be detected far above the propellant surface.