CARS (Coherent Anti-Stokes Raman Scattering) Spectroscopy of the Reaction Zone of Methane-Nitrous Oxide and RDX Propellant Flames

摘要

CARS spectra were obtained for a phi = 3.2 CH4/N20 model and nitramine propellant flames throughout the reaction and post-flame zones in order to assess kinetic mechanisms occurring in these flames. The reaction zone of the rich CH4/N20 flame was studied primarily to provide a stationary flame analog to the transient propellant flame. In the CH4/N20 flame, the decay of the initial products was observed through the Q-branch of the nu 1 and nu 3 modes of N20 and the Q, O and S branches of nu 2 and 2 nu 2 modes of CH4. The formation of the products N2, H2 Q(v' = 0 and v' = 1) and S(5) - S(9), and CO2 were also observed. Temperatures were obtained from both the H2 and N2 Q-branches. In the nitramine propellant flame, the upper bound of the gas-surface interface temperature was measured as 900 K + or - 100 K from the H2 Q-branch. Near the surface of the propellant, reactant RDX (1599 cm-1 tentatively assigned as asymetric NO2 stretch) and transients HCN (NU1) and NO are observed as moderate concentration (> or = 1%). The final product N2 is observed at low concentration, (approx. 1%), H2 (Q and S beaches) and CO are observed at higher concentration (> or = 10%). RDX and HCN decay within 2 mm of the propellant surface while NO remains constant until 4 mm where it decays with a concommitant rise in N2 concentration and temperature. H2 and CO also increase in temperature and concentration.